==== Front PhytoKeys PhytoKeys 3 urn:lsid:arphahub.com:pub:F7FCE910-8E78-573F-9C77-7788555F8AAD urn:lsid:zoobank.org:pub:66878968-5FA3-48E4-A0CA-743FBBB0315D PhytoKeys 1314-2011 1314-2003 Pensoft Publishers 10.3897/phytokeys.228.101080 101080 Monograph Bacillariophyceae Taxonomy Asia The diatom genus Ulnaria (Bacillariophyta) in China Liu Bing jsulb@outlook.com https://orcid.org/0000-0002-8516-325X 1Writing - review and editing 1 College of Biology and Environmental Sciences, Jishou University, Jishou 416000, China Jishou University Jishou China Corresponding author: Bing Liu (jsulb@outlook.com) Academic editor: Kalina Manoylov 2023 23 6 2023 228 1118 576A4D0B-FA9A-5B62-B605-71F9F54D9E9F27 1 2023 05 6 2023 Bing Liu https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract This study deals with Ulnaria species found and described from two regions of China with large climate differences during the period of 2014–2022. The first region, located in the Wuling Mountains and Hunan province, has a subtropical climate and the second in Qinghai, a northwest province of China, has a highland continental climate which is characterized by a cold and long winter and warm, short summer. Previously there were nine new Ulnaria species published from the first region. This study describes 14 additional new Ulnaria taxa, nine of which were found in the first region and five of which were found in the second region. A key to the Ulnaria species that have been described from China is provided. The main morphological characteristics for 63 Ulnaria taxa are summarized in Appendices which allow the division of these Ulnaria taxa into three groups: the seven members of group one all possess both uniseriate striae and valve marginal spines, the 42 members of group two all possess uniseriate or mostly uniseriate striae but without the valve marginal spines, and the 14 members of group three all possess mostly biseriate striae and without valve marginal spines. To summarize the morphological characters of the published Ulnaria taxa and 14 taxa described in this study several conclusions for the characterization of Ulnaria are drawn: 1) each cell has two valve-appressed, long plate-like plastids; 2) living cells of many Ulnaria species often lie in girdle view on a slide because they have deep mantles and some copulae associated with either the epivalve or the hypovalve so that the cell depth is often larger than the valve width; 3) the basic structures forming a valve include sternum, virgae, and vimines/viminules; 4) the valvocopula is a closed hoop which has a similar ultrastructure in all Ulnaria taxa but differs from the other copulae in structure; 5) the configuration of girdle bands is a common condition; 6) the life history of Ulnaria can be divided into the four series of successive stages: auxospore, initial cell, pre-normal vegetative cell, and normal vegetative cell, which is very similar to the life history of Hannaeainaequidentata (Lagerstedt) Genkal and Kharitonov; 7) the closed valvocopula is proposed as a definition character for the genus Ulnaria because demonstrating all girdle bands closed is impracticable. Key words: Girdle band structures life history stages striation patterns Ulnaria valvocopula Citation Liu B (2023) The diatom genus Ulnaria (Bacillariophyta) in China. PhytoKeys 228: 1–118. https://doi.org/10.3897/phytokeys.228.101080 ==== Body pmcIntroduction Historically, the generic name “Synedra” has been used in two different senses by diatom researchers from around the world. This situation continued until Compère (2001) proposed that Synedra, lectotypified by S.balthica Ehrenberg [=S.gaillonii (Bory) Ehrenberg], would remain the correct name and to use Ulnaria at the genus name for freshwater taxa associated with S.ulna (Nitzsch) Ehrenberg and S.ungeriana (Grunow) D.M. Williams. This study focuses on the Ulnaria from China. However, there were no diatom taxa from China placed in the genus Ulnaria until Williams (2011) transferred Synedraulnavar.repanda Q.X. Wang & Q.M You into Ulnariarepanda (Q.X. Wang & Q.M You) Williams. Thus, first the study history of Synedra in China is reviewed because possible Ulnaria taxa may have been placed in the genus Synedra before 2011 and even after 2011. The history of diatom studies in China from 1848 through 2019 has recently been documented in detail by Kociolek et al. (2020). Sixteen new Synedra taxa were described in China from 1906 to 2008 by Mereschkowsky (1906), Skvortzov (1928, 1935, 1938), Yang (1990), Bao and Reimer (1992), Liu (1994), and You et al. (2008) (Table 1, see also Kociolek et al. 2020). All of these taxa need further investigations to assess their statuses. As far as is known, none of the original material for new taxa described by either Mereschkowsky or Skvortzov has been preserved (Williams et al. 2016), so any further determination is impossible. It is difficult to judge what genus Synedraulnavar.anhuiensis Yang and S.mazamaensisvar.changbaiensis Bao and Reimer would currently belong to. Although S.ulnavar.repanda has been transferred into U.repanda, its irregular valves (see You et al. 2008, p. 420, fig. 1) may belong to the pre-normal valves rather than the normal valves following the definition of pre-normal valve by Liu and Williams (2020). Table 1. 16 new Synedra taxa described in China from 1906 to 2008. No. Taxon Reference 1 Synedraulnavar.intermedia Mereschkowsky Mereschkowsky 1906 2 Synedraulnaf.curta Skvortzov Skvortzov 1928 3 Synedraulnavar.mongolica Skvortzov Skvortzov 1928 4 Synedraaffinisvar.sinica Skvortzov Skvortzov 1935 5 Synedraamphicephalavar.asiatica Skvortzov Skvortzov 1935 6 Synedralicenti Skvortzov Skvortzov 1935 7 Synedrarumpensvar.sinica Skvortzov Skvortzov 1935 8 Synedrateneravar.sinica Skvortzov Skvortzov 1935 9 Synedraulnaf.constricta Skvortzov Skvortzov 1938 10 Synedraulnavar.lanceolataf.constricta Skvortzov Skvortzov 1938 11 Synedraulnavar.tenuirostris Skvortzov Skvortzov 1938 12 Synedravaucheriaevar.capitata Skvortzov Skvortzov 1938 13 Synedraulnavar.anhuiensis Yang Yang 1990 14 Synedramazamaensisvar.changbaiensis Bao and Reimer Bao and Reimer 1992 15 Synedracyclophoroides S.C. Liu Liu 1994 16 Synedraulnavar.repanda Q.X. Wang & Q.M. You You et al. 2008 Except for the above new Synedra taxa described in China, many known Synedra taxa were also reported in China. Fifty-one Synedra taxa which were illustrated and had some descriptions are listed in Table 2. The acceptance of the generic name Ulnaria is a slow process with Chinese diatom researchers. Qi and Li (2004), in their authoritative monograph, still used “Synedra” in two different senses three years after Ulnaria was established (Compère 2001). In Qi and Li (2004, see Table 2), Synedragaillonii (Bory) Ehrennerg should remain in Synedra, but S.ulnaria should be placed in Ulnaria as U.ulna. Most of the 51 taxa have only the illustrations of line drawings and lack the observations of scanning electron microscopy, so they also need further investigations to assess their statuses. Table 2. Synedra taxa reported from China. No. Taxon Reference 1 S.acus Kützing Hu et al. 1980 2 S.acusvar.angustissima Grunow Deng 1983 3 S.acusvar.radians (Kützing) Hustedt Zhu and Chen 2000 4 S.affinis Kützing Hu et al. 1980 5 S.amphicephala Kützing Hu et al. 1980 6 S.amphicephalavar.austriaca (Grunow) Hustedt Zhu and Chen 2000 7 S.amphicephalavar.intermedia Cleve-Euler Zhu and Chen 2000 8 S.berolinensis Lemmermann Qi and Li 2004 9 S.capitata Ehrenberg Deng 1983, Huang et al. 1983 10 S.dorsiventralis Otto Müller Zhu and Chen 2000 11 S.familica Kützing Qi and Li 2004 12 S.fasciculata (C. Agardh) Kützing Li et al. 2005 13 S.gaillonii (Bory) Ehrennerg Qi and Li 2004 14 S.goulardii Brebisson Qi and Li 2004 15 S.investiens W. Smith Qi and Li 2004 16 S.mazamaensis Soverergn Qi and Li 2004 17 S.minuscula Grunow Qi and Li 2004 18 S.montana Krasske Qi and Li 2004 19 S.nana Meister Qi and Li 2004 20 S.parasitica (W. Smith) Hustedt Zhu and Chen 2000 21 S.parasiticavar.subconstricta (Grunow) Hustedt Zhu and Chen 2000 22 S.pulchella (Ralfs ex Kützing) Kützing Qi and Li 2004 23 S.robusta Ralfs Jin et al. 1982 24 S.rumpens Kützing Zhu and Chen 2000 25 S.rumpensKützingvar.familiaris (Kützing) Hustedt Huang et al. 1983 26 S.rumpensKützingvar.meneghiniana Grunow Deng 1983, Zhu and Chen 2000 27 S.rumpensKützingvar.scotica Grunow Zhu and Chen 2000 28 S.rumpensKützingvar.sinica Skvortzov Qi and Li 2004 29 S.socia Wallace Qi and Li 2004 30 S.tabulata (Agardh) Kützing Qi and Li 2004 31 S.tabulatavar.fasciculata (C.A. Agardh) Hustedt Deng 1983 32 S.tabulatavar.parava (Kützing) Hustedt Qi and Li 2004 33 S.tabulatavar.obtusa (Arnott) Hustedt Zhu and Chen 2000 34 S.tabulatavar.rostrata (Juhlin-Dannfelt) Cleve-Euler Zhu and Chen 2000 35 S.tabulatavar.genuina Cleve-Euler Deng 1983 36 S.tenera W. Smith Zhu and Chen 2000 37 S.ulna (Nitzsch) Ehrenberg Hu et al. 1980 38 S.ulnavar.aequalis (Kützing) Brun Zhu and Chen 2000 39 S.ulnavar.amphirhynchus (Ehrenberg) Grunow Zhu and Chen 2000 40 S.ulnavar.biceps (Kützing) Schönfeldt Deng 1983 41 S.ulnavar.chaseana Thomas Qi and Li 2004 42 S.ulnavar.constracta Østrup Zhu and Chen 2000 43 S.ulnavar.danica (Kützing) Grunow Deng 1983 44 S.ulnavar.danicaf.continua (Kützing) Grunow Deng 1983 45 S.ulnavar.impressa Hustedt Qi and Li 2004 46 S.ulnavar.oxyrhynchus (Kützing) Van Heurck Zhu and Chen 2000 47 S.ulnavar.oxyrhynchusf.constricta Skvortzow Zhu and Chen 2000 48 S.ulnavar.ramesi (Héribaud) Hustedt Qi and Li 2004 49 S.ulnavar.spathulifera (Grunow) Van Heurck Zhu and Chen 2000 50 S.ulnavar.splendcns (Kützing) Grunow Deng 1983 51 S.vaucheriae (Kütz.) Kützing Hu et al. 1980 From 2017 to 2020, nine new Ulnaria species found in China were published (Liu et al. 2017, 2019a, b; Williams and Blanco 2019, 2020; Table 3). These nine new species were well documented through observations with light and scanning electron microscopy, and three of which were found to possess mostly biseriate striae (U.ulnabiseriata D.M. Williams & Bing Liu, U.gaowangjiensis Bing Liu & D.M. Williams and U.oxybiseriata D.M. Williams & Bing Liu). The observation of girdle bands on seven of the nine new Ulnaria species greatly expanded our understanding of these for this genus. Table 3. Nine new Ulnaria taxa described in China from 2017 to 2020. No. Taxon Reference 1 U.sinensis Bing Liu et D.M. Williams Liu et al. 2017 2 U.ulnabiseriata D.M. Williams et Bing Liu Liu et al. 2017 3 U.gaowangjiensis Bing Liu et D.M. Williams Liu et al. 2017 4 U.rhombus D.M. Williams Liu et al. 2019a 5 U.wulingensis Bing Liu Liu et al. 2019a 6 U.oxybiseriata D.M. Williams & Bing Liu Liu et al. 2019b 7 U.jinbianensis S. Blanco & Bing Liu Liu et al. 2019b 8 U.dongtingensis Bing Liu Liu et al. 2019b 9 U.hunanensis Bing Liu Liu et al. 2019a, Williams and Blanco 2019 Although Ulnaria was established in 2001, the use of the name Ulnaria is currently a nomenclatural decision (Van de Vijver and Cocquyt 2009) because Ulnaria does not have a clear definition due to the type species Ulnariaulna being an uncharacterized species (Morales et al. 2014). To get a clearer understanding of U.ulna, Lange-Bertalot and Ulrich (2014) investigated Bacillariaulna Nitzschia (the basionym of U.ulna). But no original material can be found, and the type locality does not exist anymore. They then epitypified B.ulna (Lange-Bertalot and Ulrich 2014, p. 66). From their description of the epitype, two important points are worth paying attention to: one is most of the frustules lay in girdle view and the other is girdle bands are closed – which was provided as a defining feature for Ulnaria by Williams (2011), who considered the studied data of Ulnaria and stated, “In the case of any taxon including S.ulna, closed girdle bands are of significance: they are hypothesized as a synapomorphy for that group, one of its defining features”. A lot of research on Ulnaria has proved that the presence of closed girdle bands is a useful differentiating character from other similar genera (e.g., Morales et al. 2014; Liu et al. 2017; Cantonati et al. 2018; Liu et al. 2019a, b; Williams 2020). However, closed girdle bands in some published Ulnaria species were not confirmed by the authors [e.g., U.macilenta E. Morales, C.E. Wetzel & S.F. Rivera (Morales et al. 2014); U.verhaegeniana Van de Vijver, M. de Haan, Mertens & Cocquyt (Van de Vijver et al. 2017)]. For these cases, Van de Vijver et al. (2017, p. 223) claimed that “the general appearance, the presence of two rimoportulae, the characteristic ocellulimbus and the internal structure of the striae and areolae” can be diagnostic characters for Ulnaria. To date, according to the Algaebase.org website (Guiry and Guiry 2022), there are approximately 50 taxa accepted taxonomically in the genus Ulnaria. Reports of the phylogeny of Ulnaria are rare. Kulikovskiy et al. (2016) carried out a phylogenetic analysis of two new Ulnaria species and their result showed that Ulnaria is a closely related but independent branch from Fragilaria Lyngbye sensu stricto. Similarly, Zakharova et al. (2020) conducted a phylogenetic analysis of two clones from the genus Ulnaria and their result supported that Ulnaria is an independent clade. Both previous phylogenetic studies were based on only one gene (rbcL) fragments of five Ulnaria species. Appendices 1–3 summarized the main morphological characters for 63 Ulnaria taxa, 49 of which have been published and 14 of which are first described in this paper. Many of these 63 Ulnaria taxa are well-documented so that we can see a wide range of morphological diversity in the genus Ulnaria. Firstly, the cell sizes can be very different among the Ulnaria taxa due to the valve length varying between 14–512 μm and the valve width between 2.5–12 (15) μm. Secondly, there are seven Ulnaria species producing valve marginal spines (Appendix 1). Interestingly, these seven species all possess uniseriate striae, i.e., so far, no Ulnaria species bearing biseriate striae are found to produce valve marginal spines (see Appendix 2). Thirdly, 14 Ulnaria species possess mostly biseriate striae (Appendix 2). Among these 14 species, only U.gusliakovii Genkal, Shcherbak & Semenyuk lacks a central area (Genkal et al. 2022) and the other 13 taxa have different shapes of central areas (Appendix 2). Finally, 42 Ulnaria taxa have uniseriate striae but do not produce marginal spines (Appendix 3). Ulnaria has been defined by the possession of closed girdle bands. However, the present situation is that there are only 40 Ulnaria species which were found to possess closed valvocopula or girdle bands and the nature of girdle bands for the other 23 Ulnaria species is still unknown (see Appendices 1–3). Hopefully, similar to this study, researchers will try to document the structures of girdle bands in their future studies of Ulnaria. Materials and methods Site description and sampling The diatom samples studied herein were collected from the Wuling Mountains, Dongting Lake and Qinghai province beginning in 2014. The Wuling Mountains, which stretch across Chongqing, Hunan, Hubei, and Guizhou provinces, are one of the ten biodiversity hotspot ecoregions considered as conservation priorities in China (Tang et al. 2006). It belongs to the mountain climate, which is a transition from the sub-tropical to the warm temperate climate (see Liu et al. 2017 for further information). Dongting Lake is the second largest freshwater lake in China and is located between 28°30'N–30°20'N, 111°40'–113°40'E in the northeast part of Hunan province (see Liu et al. 2018 for further details). Qinghai is an inland province of China, which has an average elevation greater than 3000 m a.s.l. The plateau accounts for 80% of Qinghai landscape so its climate belongs to the plateau continental climate. The diatom samples from Wuling Mountains and Qinghai province were collected from the surfaces of 3–7 submerged stones from each sampling cite; the diatom samples from Dongting Lake were collected from its littoral zone topsoil by scraping the 1–2 mm surface sediment. During sample collection, temperature, pH, and conductivity were measured in situ (three repetitions) with a portable multimeter (HQ40D, HACH Company). The collected diatom samples which were not added 70% alcohol were used to observe the living cells. 100 μl diatom samples were transferred into a round chamber (diameter 14 mm, depth 0.35 mm) located in the middle of a custom-made slide by using a pipette, then examined using a Leica DM3000 light microscopy (LM) equipped with a Leica MC190 HD digital camera. The collected diatom samples which were added 70% alcohol were processed (cleaned) for microscopic examination with 10% HCl and 30% H2O2. Permanent slides were prepared using Naphrax mountant and examined using the same light microscopy as above. Slides are deposited in the Herbarium of Jishou University, Hunan, People’s Republic of China (JIU) (Herbarium acronyms follow Index Herbarium http://sweetgum.nybg.org/science/ih/). Samples were also examined using scanning electron microscopy (SEM). Several drops of the cleaned diatom material were air-dried onto glass coverslips. The coverslips were attached to aluminium stubs using double-sided conductive carbon strip and sputter-coated with platinum (Cressington Sputter Coater 108auto, Ted Pella, Inc.). Samples were examined and imaged using a field emission scanning electron microscopy (FESEM) Sigma HD (Carl Zeiss Microscopy) available at Huaihua University, China. Morphological terminology Morphological terminology follows Anonymous (1975), Ross et al. (1979), Mann (1982), Williams (1986), Round et al. (1990), Cox (2012), and Lange-Bertalot and Ulrich (2014). Life cycle terminology mostly follows Kaczmarska et al. (2013) and Liu and Williams (2020). To avoid any ambiguity and misunderstanding, the terms most used in this study are illustrated in Figs 1 and 2, a part of them are defined below, and other common terms are not repeated here. 10.3897/phytokeys.228.101080.figure1 3AD967C3-CD69-5D43-8C5E-105F43D36054 Figure 1. Valve characters used in the descriptions of Ulnaria taxa. https://binary.pensoft.net/fig/867589 10.3897/phytokeys.228.101080.figure2 2C6EBD5D-7576-5B02-8FA9-3540682FEE78 Figure 2. Characters of valve and girdle bands used in the descriptions of Ulnaria taxa. https://binary.pensoft.net/fig/867590 Valvocopula abvalvar edge: the edge that is farther from the valve face. Valvocopula advalvar edge: the edge that is closer to the valve face. Closing plate: a plate that does not completely occlude the outside opening of areola. This plate is usually solid (sometimes with several perforations) and has a few struts attaching it to each areolar wall. Configuration of girdle bands: the ratio between the number of girdle bands associated with the epivalve and the number associated with the hypovalve in a diatom cell. Ghost striae: the faint “striae” composed of unperforated grooves in the central area of the valve interior (visible under SEM). These grooves look like “striae” under LM but are not true striae. Mixed stria: the striae are usually divided into three types: uniseriate, biseriate and multiseriate striae. A mixed stria is a stria composed of at least two of the previous three stria types. Pre-normal vegetative frustule: the pre-normal vegetative period is the time between immediately after the initial cell’s first division and the presence of the first new normal vegetative cells. The frustule occurring during this period is termed pre-normal vegetative frustule. Vimines (s. vimen): the cross-connecting tiny ribs between two adjacent virgae defining areolae in uniseriate striae. Viminules (s. viminule): the interconnecting tiny ribs between two adjacent virgae which define areolae in the biseriate or multiseriate striae. Virga (pl. virgae): the transverse silica rib between two adjacent striae. Results Life history of Ulnaria – a case study from U.ulnabiseriata (Figs 3–13) The life history of Ulnaria can be divided into the following four series of successive stages: auxospore, initial cell, pre-normal vegetative cell, and normal vegetative cell. Unfortunately, we did not find an auxospore of Ulnaria, but the initial cell, pre-normal vegetative cell, and normal vegetative cell of U.ulnabiseriata were all documented using LM and SEM. The life history, from the initial cell, via pre-normal vegetative cells, to normal vegetative cell, is a process from chaos to order, i.e., the shapes of initial cell and pre-normal vegetative cells gradually become more and more regular and symmetrical from irregular and asymmetrical (see Figs 3, 4, 9). 10.3897/phytokeys.228.101080.figure3 1FF40FAD-2D81-5F38-9F63-4E71AFA927EC Figure 3. Life history of Ulnariaulnabiseriata, from initial cell, via pre-normal cells, finally to normal cell, ×400, LMA initial frustule showing its cylindrical and twisted outline, central area flanked by striae on one side B–N pre-normal frustules, note twisted frustules with laterally located sterna (B–E), one apex twisted and with almost centrally located sterna (F, G), almost centrally located sterna and complete central areas (H–N). O Normal valve. https://binary.pensoft.net/fig/867591 10.3897/phytokeys.228.101080.figure4 71A8F513-1777-5A8C-B253-3DFA4AC4B699 Figure 4. Life history of Ulnariaulnabiseriata, from initial cell, via pre-normal cells, finally to normal cell, external view, SEMA initial frustule, note its cylindrical and twisted frustule (for details see Fig. 5) B–H pre-normal frustules/valves, note twisted frustules with smoothly tapering apices (B–E, H), protracted and sub-capitate to rostrate apices (F, G) I normal valve. Note: the number value at the top of each figure refers to the length of each specimen. https://binary.pensoft.net/fig/867592 Initial cells: Two initial cells were found and measured. One is 240 μm long (Fig. 3A), the other is 217 μm long (Fig. 4A). The initial frustule has an arcuate, cylindrical, and twisted outline (Figs 3A, 4A, 5A). It has a small central area flanked by some striae on one side (Fig. 5C, arrow), the mixed striae are composed of partial biseriate and partial uniseriate, the mantle is not well differentiated from the valve face (Fig. 5D, double-headed arrow), the valve lacks a sternum except at one apex where a short laterally located sternum is produced (Fig. 5F, double-headed arrow). The ocellulimbus is not inset yet, extending onto the valve surface, and its partial pervalvar rows of porelli are not vertical (Fig. 5F, arrow). Perizonium and girdle bands are not observed. 10.3897/phytokeys.228.101080.figure5 F6AF4ED6-3B31-5CE8-BE70-AEF9C7CDA92E Figure 5. Initial frustule of Ulnariaulnabiseriata, external view, SEMA Initial frustule, note its arcuate, cylindrical, and twisted outline B, C details of middle part from A, note small central area flanked by striae on one side (C, arrow), mixed striae, and underdeveloped sternum (i.e., striae continue across valve surface) D apical detail from A, note mantle not well differentiated from valve face (double-headed arrow), and virgae and vimines/viminules occurring nearly on the same plane E, F other apical details from A, note laterally located sternum present only near one apex (F, double-headed arrow), ocellulimbus flush with and extending onto valve surface, and its partial pervalvar rows of porelli not perpendicular to the valve plane (F, arrow). Scale bars: 20 μm (A); 2 μm (B–F). https://binary.pensoft.net/fig/867593 Pre-normal vegetative cells: The valve length range of pre-normal vegetative cells is 196–250 μm (n = 41). Early pre-normal vegetative frustules may be twisted and have laterally located sterna (Fig. 3B–E), then progress to only one apex twisted with nearly centrally located sterna (Fig. 3F, G); finally, they progress to having centrally located sterna and complete central areas (Fig. 3H–N). Pre-normal vegetative frustules may also initially be twisted with smoothly tapering apices (Fig. 4B–E, H), then their apices become protracted to rostrate or sub-capitate (Fig. 4F, G). Figure 6 demonstrates the details of an early pre-normal frustules. This pre-normal frustule has a cylindrical and twisted outline (Fig. 6A), small central area flanked by striae on only one side (Fig. 6B), laterally located sternum and ocellulimbus which is flush with the surface of the valve (Fig. 6C–F). Figure 7 demonstrates the details of a late pre-normal frustule. This pre-normal frustule has a constricted outline in its middle part (Fig. 7A, B), almost centrally located sternum, underdeveloped closing plates and undifferentiated mantle (Fig. 7C, D), and uniseriate striae present at apices and slightly inset ocellulimbus (Fig. 7E, F). Figure 8 demonstrates the details of a likely late pre-normal frustule. This pre-normal frustule has slightly twisted outline and almost centrally located sternum, complete central area (Fig. 8A), well differentiated mantle (mantle met the valve surface at a right angle, Fig. 8B–E), biseriate striae present at apices (Fig. 8C), and developed closing plates (Fig. 8F, two wavy arrows), inset ocellulimbus with pervalvar rows perpendicular to the valve plane and few serrated apical projections protruding over it (Fig. 8F, three black arrows and two white arrows). Figure 9A–H shows the internal views of eight pre-normal valves. These eight pre-normal valves generally have irregular and asymmetrical outlines. Figure 10 demonstrates the internal details of a late pre-normal valve. This pre-normal valve has undulating valve margins (Fig. 10A, B, D), one apex slightly twisted (Fig. 10E), biseriate striae present at apices (Fig. 10C, F). Figure 11 demonstrates the details of a likely latest pre-normal valve with a valvocopula. This valvocopula has the same structure as that observed in the normal vegetative valve, i.e., the valvocopula is a closed hoop, surrounding whole valve margin, bearing a mostly continuous row of poroids dividing pars interior from pars exterior, located at midline (Fig. 11A–E), lacking ornamentation at both apices (Fig. 11D, F). Its advalvar edge has a row of serrated projections which are aligned with the virgae (Fig. 11B, three arrows). 10.3897/phytokeys.228.101080.figure6 03F3C25E-B7B3-5166-8313-EC58649FC8FB Figure 6. Pre-normal frustule of Ulnariaulnabiseriata, external view, SEMA pre-normal frustule, note its cylindrical and twisted outline B, C middle part details from A, note small central area flanked by striae on one side (B, two arrows), girdle bands lacking D, E apical details from A, note laterally located sternum (E, double-headed arrow) and flush ocellulimbus F other half from A, note laterally located sternum (double-headed arrow). Scale bars: 20 μm (A); 4 μm (B–F). https://binary.pensoft.net/fig/867594 10.3897/phytokeys.228.101080.figure7 C23545D5-3CDC-5B3D-A0E6-65E56BEC537E Figure 7. Pre-normal frustule of Ulnariaulnabiseriata, external view, SEMA pre-normal valve B middle part detail from A, note its constricted outline in the middle C, D proximal parts of valve from A, note closing plates underdeveloped E, F apical details from A, note slightly inset ocellulimbus. Scale bars: 20 μm (A); 3 μm (B–F). https://binary.pensoft.net/fig/867595 10.3897/phytokeys.228.101080.figure8 4A4CBD26-0673-5A3A-8668-F3713FDE4C97 Figure 8. Details of late pre-normal frustule of Ulnariaulnabiseriata from Fig. 4D, external view, SEMA middle part detail, note rectangular central area B half valve, note its arcuate outline C one apical detail, note biseriate striae developed at apex D, E other half part of valve, note slightly twisted frustule and mantle joining the valve face at a right angle F apical detail from D, note inset ocellulimbus, developed closing plates (two wavy arrows), and few serrated apical projections protruding over the ocellulimbus (three black arrows and two white arrows). Scale bars: 6 μm (A–E); 3 μm (F). https://binary.pensoft.net/fig/867596 10.3897/phytokeys.228.101080.figure9 D26E1CEC-B6F5-537B-899A-CB45A11B1E26 Figure 9. Valves of Ulnariaulnabiseriata, internal view, SEMA–H eight pre-normal valves, note irregular and asymmetrical valve outlines I normal valve, note its linear-lanceolate outline. Note: the number value at the top of each figure refers to the length of each specimen. https://binary.pensoft.net/fig/867597 10.3897/phytokeys.228.101080.figure10 877AD9D8-B789-5418-B571-F00AC12FF75C Figure 10. Details of late pre-normal value of Ulnariaulnabiseriata from Fig. 9A, internal view, SEMA middle constricted part of valve B, C details of one apex D–F details of other apex, note still slightly twisted valve. Scale bars: 6 μm (A, B, D, E); 3 μm (C, F). https://binary.pensoft.net/fig/867598 10.3897/phytokeys.228.101080.figure11 07A0066E-38BB-567E-8B9B-DAFE95C12509 Figure 11. Details of late pre-normal valve of Ulnariaulnabiseriata from Fig. 9G, internal view, SEMA, B middle parts of valve, note a row of poroids located at midline (A, double-headed arrow) and a row of serrated projections aligned with each virga (B, three arrows) C–F apical details, note the closed two apices of valvocopula (D, F, arrow respectively). Scale bars: 6 μm (A, C); 3 μm (B, D–F). https://binary.pensoft.net/fig/867599 Normal vegetative cells: The valves of U.ulnabiseriata (Figs 12 and 13) are characterized by their lanceolate outline, rectangular central area (Figs 12B, 13A), mostly biseriate striae (Figs 12C, E, 13B–F), well developed closing plates and ocellulimbus (Fig. 12D, F), and rostrate to sub-capitate apices (Figs 3O, 4I, 9I, 12A). 10.3897/phytokeys.228.101080.figure12 0F27EDD2-2D2F-56BE-8FE9-7937D5CB3A54 Figure 12. Normal valve of Ulnariaulnabiseriata, external view, SEMA complete valve B middle detail, note the rectangular central area C, D two apices, note centrally located sternum and rostrate apices E, F apical details, note inset ocellulimbus and some outgrowths protruding over it (F, three arrows). Scale bars: 20 μm (A); 3 μm (B, C, E); 1 μm (D, F). https://binary.pensoft.net/fig/867600 10.3897/phytokeys.228.101080.figure13 9EBD0DF6-2BA5-5723-85A3-1AE9DCE50B89 Figure 13. Details of normal valve of Ulnariaulnabiseriata from Fig. 9I, internal view, SEMA middle part, note parallel valve margins, rectangular central area B–F apical details, note centrally located sternum and virgae raised above from viminules. Scale bars: 6 μm (A–F). https://binary.pensoft.net/fig/867601 The morphological features that change during the life circle of U.ulnabiseriata are summarized in Table 4. From initial frustule/valve, via pre-normal vegetative frustule/valve, to normal vegetative frustule/valve, the girdle band numbers, valve outline, valve apices, sternum, central area, virgae and viminules, closing plates, and ocellulimbus, all gradually become normal (Table 4). Table 4. Features of initial cell, pre-normal and normal vegetative frustule/valve in U.ulnabiseriata. Feature Initial frustule/valve Pre-normal vegetative frustule/valve Normal vegetative frustule/valve Girdle bands Not found Not found to a few present 4 copulae associated with epivalve Valve outline Cylinder-like, twisted Irregular and asymmetrical Linear-lanceolate Valve apex Rounded Rounded, rostrate, or sub-capitate Rostrate to sub-capitate Sternum Non-existent except lateral sternum present only at apex Lateral to nearly central sternum Central sternum, i.e., normal, situated on the midline of valve Central area Present, small, with short striae at one side From small to rectangular Rectangular Virga/viminule Virgae and vimines/viminules almost flush with each other Vimines/viminules slightly lower than virgae Virgae raised, viminules sunken Stria Mixted striae in the middle, uniseriate striae near apex Gradually become mostly biseriate striae (striae near apex become biseriate too) Mostly biseriate striae Closing plate Not found Not found to present Well developed Rimoportula number per valve Two Two Two Ocellulimbus Extending on valve face, pervalvar row of porelli not perpendicular to the valve plane Pervalvar rows of porelli gradually becoming perpendicular to the valve plane Pervalvar rows of porelli all perpendicular to the valve plane Taxonomic treatment Artificial key to 24 Ulnaria species described from China 1 Biseriate striae 2 – Uniseriate striae 9 2 Panduriform valve outline 1. U.pandurata-biseriata – Not panduriform valve outline 3 3 Apiculate apices 2. U.oxybiseriata – Not apiculate apices 4 4 Linear valve outline 3. U.wuling-biseriata – Linear-lanceolate or lanceolate valve outline 5 5 Linear-lanceolate valve outline 6 – Lanceolate valve outline 7 6 Constricted central valve margins with rostrate apex 4. U.constricta-biseriata – Parallel central valve margins with rostrate apices 5. U.gaowangjiensis 7 Slightly constricted central valve margins with capitate to sub-capitate apices 6. U.sangzhi-biseriata – Parallel central valve margins 8 8 Central area apically rectangular 7. U.ulnabiseriata – Central area very variable 8. U.jishou-biseriata 9 Interlocking spines produced on valve margins 9. U.sinensis – Interlocking spines lacking 10 10 Undulate valve outline 10. U.repanda – Not undulate valve outline 11 11 Panduriform valve outline 11. U.pandurata-uniseriata – Not panduriform valve outline 12 12 Parallel distal regions of valve present 13 – Parallel distal regions of valve lacking 15 13 Rhombic valve outline 12. U.rhombus – Not rhombic valve outline 14 14 Parallel distal region of valve more than 20 μm long 13. U.wulingensis – Parallel distal region of valve less than 20 μm long 14. U.hunanensis 15 Central area completely lacking 16 – Central area present 18 16 Valve width less than 5 μm 15. U.qinghainensis – Valve width more than 5 μm 17 17 Lanceolate valve outline 16. U.hupingensis – Linear-lanceolate valve outline 17. U.xieriverensis 18 Central area complete 19 – Central area very variable 21 19 Linear-lanceolate valve outline 18. U.jinbianensis – Lanceolate valve outline 20 20 Length of parallel central margins equal to the length of the central area 19. U.dongtingensis – Length of parallel central margins much larger than the length of the central area 20. U.fanjingensis 21 Capitate apices 21. U.neobiceps – Not capitate apices 22 22 Linear-lanceolate valve outline 22. U.chengduoensis – Lanceolate valve outline 23 23 Rostrate apices 23. U.menyuanensis – Sub-capitate apices 24. U.blancoi New species descriptions Taxon classification Plantae Licmophorales Ulnariaceae  Ulnaria constricta-biseriata Bing Liu sp. nov. 67A4AC44-FDA2-54DD-AFE1-BC094E02D77A Figs 14 , 15 , 16 , 17 , 18 Holotype. Slide JIUDIA202301, specimen circled on slide, illustrated as Fig. 14A. Registration. PhycoBank http://phycobank.org/103807 Type locality. China. Guizhou province: Fanjing Mountain, Temple Longquan, Heiwan River (27°51'36"N, 108°45'51"E, 532 m a.s.l.), collected by Bing Liu, December 31, 2015. Description. LM (Fig. 14). Valves linear-lanceolate, constricted at centre, apex rostrate to sub-capitate (Fig. 14A–H, see also Figs 16A, 17A, 18A, E). Valve dimensions (n = 35): length 66–166 μm, width 5.5–8 μm at constricted centre, narrower by 0.2–1.1 µm than at its widest. Valve margins parallel with rostrate to sub-capitate apices (Fig. 14A–H). Sternum central, distinct, extending whole length of valve. Rectangular or square central area. Ghost striae often present in central area (e.g., Fig. 14A–E). Striae parallel, radiate only at the poles. Striae mostly opposite one another across sternum. Stria density 10–12 (often 11) in 10 μm. 10.3897/phytokeys.228.101080.figure14 F1321FC5-8CFA-5232-A9A0-D5B22E081522 Figure 14. Ulnariaconstricta-biseriata sp. nov., ×1000, LMA–H eight valves exhibiting a size diminution series, note the constricted middle margins A micrograph of holotype specimen. Scale bar: 20 μm. https://binary.pensoft.net/fig/867602 SEM (Figs 15–18). Frustule in girdle view rectangular (Fig. 15A). Epivalve with up to three closed copulae (Fig. 16B–F), 2nd and 3rd copulae bearing two rows of poroids (2nd = B2, Fig. 15B–E, white wavy arrow; 3rd = B3, Fig. 15D, E, black arrow). Valvocopula closed, surrounding whole valve margin (Fig. 16A), bearing a mostly continuous row of poroids at the midline, dividing pars interior from pars exterior (Fig. 16B–D), lacking ornamentation at both poles (Fig. 16C, D); its advalvar edge having a row of serrated projections, each corresponding to a virga internally (Fig. 16B–D, two arrows respectively). Valve central area rectangular (Figs 17B, E, 18B, F). Striae constructed from series of relatively wide virgae interconnected with thin viminules, closing plates present with a few struts, affixed to the areolar wall (Figs 17B–F, 18B–D, F; closing plate see Fig. 17F, wavy arrow). Valves with mixed striae, mostly biseriate, formed by viminules; each stria situated opposite each other across sternum, equidistant until radiate at poles, and becoming uniseriate near sternum (Figs 17B–F, 18B–D, F). One rimoportula present at each pole, externally expressed as a simple hole (Fig. 17D, F), internally bilabiate, situated close to sternum (Fig. 18C, D). Apical pore fields ocellulimbus, consisting of ca. 23 pervalvar and 11 transverse rows of porelli (both pervalvar and transverse rows unequal in length). A few serrated apical outgrowths protruding over each ocellulimbus (Fig. 17C, D, F, one arrow respectively). 10.3897/phytokeys.228.101080.figure15 519FE275-D085-5F79-8F00-2EC5554CDDDA Figure 15. Ulnariaconstricta-biseriata sp. nov., girdle view, SEMA a frustule with a collapsed hypovalve B–D details from A, note three copulae (labeled B1 to B3) associated with the epivalves and two rows of poroids present on B2 (wavy arrows) and B3 (arrows) E, F the apices with three copulae visible (labeled B1 to B3) associated with the epivalves and two rows of poroids produced on B2 (wavy arrow) and B3 (arrow). Scale bars: 20 μm (A); 3 μm (B–F). https://binary.pensoft.net/fig/867603 10.3897/phytokeys.228.101080.figure16 FBD83DCA-2245-59AF-98D2-EBD2748BDD17 Figure 16. Ulnariaconstricta-biseriata sp. nov., internal view, SEMA a complete valve with a valvocopula B middle detail from A, note serrated projections at the advalvar edge (two arrows) C, D two apical details from A, note the closed nature of valvocopula and serrated projections at the advalvar edge (two arrows respectively). Scale bars: 20 μm (A); 4 μm (B–D). https://binary.pensoft.net/fig/867604 10.3897/phytokeys.228.101080.figure17 F0754712-136D-5FD1-9C38-B024138587AC Figure 17. Ulnariaconstricta-biseriata sp. nov., external view, SEMA a complete valve B middle part from A showing the constricted middle margins and central area forming a rectangular hyaline region C, D two apical details from A, note a few serrated apical projections protruding over the ocellulimbus (two black arrows) E another middle part, note two constricted middle margins F another apex, note a few serrated apical projections protruding over the ocellulimbus (arrow) and the closing plates (wavy arrow). Scale bars: 20 μm (A); 2 μm (B–F). https://binary.pensoft.net/fig/867605 10.3897/phytokeys.228.101080.figure18 411F2EAB-6F60-5F56-8B37-A2DBDA40AFAA Figure 18. Ulnariaconstricta-biseriata sp. nov., internal view, SEMA a complete valve B middle part from A, note two constricted middle margins and some ghost striae C, D two apical details from A, note the striae mostly biseriate and two helictoglossae E another complete valve F middle detail from E, note two constricted middle margins and some ghost striae. Scale bars: 20 μm (A, E); 2 μm (B–D, F). https://binary.pensoft.net/fig/867606 Etymology. The specific epithet is formed from two terms: constrict and biseriate, reflecting the constricted valve central margins and the mostly biseriate striae of the valve. Ecology and distribution. The sampling site is close to the headwaters of the Heiwan River, which originates in the Fanjing Mountain National Nature Reserve. The diatom samples were scraped off of the stone surfaces. The following environmental parameters were measured in the field. Conductivity was 49.7 ± 0.2 μS∙cm-1, pH was 7.7 ± 0.1 and water temperature was 9.4 ± 0.1 °C. So far, its distribution is known only from the type locality. To sum up, U.constricta-biseriata lives on the stone surfaces of the headwaters of a mountainous river. Discussion. Ulnariaconstricta-biseriata is characterized by its linear-lanceolate valve outline, constricted valve central margins, and mostly biseriate striae. Ulnariacontracta (Østrup) E.A. Morales & M.L. Vis has also constricted valve central margins, but it differs from U.constricta-biseriata by its lanceolate valve outlines and mostly uniseriate striae (see Morales et al. 2007, p. 61, figs 48–55, p. 63, figs 56–61, as Synedraulnavar.contracta Østrup). Taxon classification Plantae Licmophorales Ulnariaceae  Ulnaria jishou-biseriata Bing Liu sp. nov. A7A935AD-ABDF-5126-AC85-0B9FFB073B15 Figs 19 , 20 , 21 , 22 , 23 , 24 , 25 Holotype. Slide JIUDIA202302, specimen circled on slide, illustrated as Fig. 20D. Registration. PhycoBank http://phycobank.org/103808. Type locality. China. Hunan province: Jishou City, Lianaiqiao, Donghe River (28°18'51.3"N, 109°43'41.6"E, 200 m a.s.l.), collected by Bing Liu, December 9, 2016. Description. LM (Figs 19, 20). Frustules rectangular in girdle view (Figs 19A, B, 20A), lanceolate in valve view (Fig. 19C, D). Chloroplasts two long plates per cell, valve-appressed (Fig. 19A), covering large portion of valve face in valve view (Fig. 19C, D). Valves lanceolate with prolonged, rostrate poles (Fig. 20B–J, see also Figs 23A, 24A, 25A), dimensions (n = 38): length 139–200 μm, width 6–8 μm at centre. Valve margins parallel near central area, gradually tapering towards rostrate poles (Fig. 20B–J). Sternum central, distinct, narrow, regular. Central area having three arrangements: extending towards both margins forming square to rectangular (Fig. 20B, J) or round hyaline space (Fig. 20C–E); extending to one margin with other margin flanked by few short striae (Fig. 20G–I); both margins bordered with few short striae (Fig. 20F). Ghost striae sometimes present (e.g., Fig. 20C, I) in central area. Striae parallel, radiate only at poles, and mostly opposite one another across sternum. Stria density 10–12 (often 11) in 10 μm. 10.3897/phytokeys.228.101080.figure19 08D5281C-F174-5A67-B3A0-ED65C88A3CD7 Figure 19. Ulnariajishou-biseriata sp. nov., ×400, LMA A cell in girdle view, note two long valve-appressed chloroplasts per cell B a dividing cell in girdle view, note the chloroplasts are distributed along the pervalvar axis C, D two cells in valve view, note the long plate of chloroplast. Scale bar: 20 μm. https://binary.pensoft.net/fig/867607 10.3897/phytokeys.228.101080.figure20 669AEB92-1048-53F5-817E-F2E89E509860 Figure 20. Ulnariajishou-biseriata sp. nov., ×630, LMA a frustule in girdle view, note the rectangle outline B–J nine valves exhibiting a size diminution series, note the lanceolate valve outline and the variable central areas D micrograph of holotype specimen. Scale bar: 20 μm. https://binary.pensoft.net/fig/867608 SEM (Figs 21–25). In some dividing cells, both epivalve and hypovalve associated with valvocopula and two copulae, forming 3:3 configuration of girdle bands (Fig. 21A–F, bands labelled B1–B3, B1 = valvocopula); sometimes epivalve associated with valvocopula and three copulae, whereas hypovalve associated with valvocopula and two copulae, forming 4:3 configuration (Fig. 22A–D). Copulae sometimes bearing two rows of poroids near poles (Fig. 21C–F). Valvocopula a closed hoop, same shape as valve outline, closely attached to mantle interior, surrounding the valve internal margin (Fig. 23A); bearing a mostly continuous row of poroids dividing pars interior from pars exterior located at midline (Fig. 23B–E), some isolated poroids visible in pars exterior (Fig. 23B, two arrows). At the advalvar edge, valvocopula produces a row of serrated projections, each corresponding to a virga internally (Fig. 23C, arrows). Valvocopula lacking ornamentation at both poles (Fig. 23D, E, black arrow respectively). Striae continuing onto mantle, absent from centre (Fig. 24B). Valve face and mantle intersecting almost at a right angle (Fig. 24B–F). Valve characterized by relatively wide virgae, interconnected with thin viminules, and closing plates with few struts fixing them onto each areolar wall (Fig. 24C, D). Valve has two types of mixed striae: one composed of a biseriate main part and a uniseriate minor part near sternum (usually 1 or 2 areolae), which are distributed on most of the valve face except each apex, and the other composed of a uniseriate main part and a biseriate minor part, which are only present near each apex (Figs 24C, D, 25B–F). Ocellulimbus composed of ca. 18 pervalvar and 10 transverse rows of porelli (both pervalvar and transverse rows unequal in length). A few serrated apical outgrowths protruding over each ocellulimbus (Fig. 24C, three arrows). Internally, virgae transversely extending towards mantle from sternum. Striae situated almost opposite each other across sternum and becoming uniseriate near sternum (Fig. 25B–F). Central area with three arrangements: extending to one margin, bordering with several short striae (Figs 24B, external, 25E, internal); bordering both margins with several short striae (Figs 24E, external, 25F, internal); or extending to both margins forming transapically rectangular fascia (Figs 24F, external, 25B, internal). One rimoportula at each pole (Figs 23D, E, 24C, D, 25D), occasionally two produced at an apex (Fig. 25C). External opening of rimoportula expressed as a simple hole with different shapes (Fig. 24C, D); internally bilabiate, situated close to sternum, aligned with striae (Fig. 25C, D). 10.3897/phytokeys.228.101080.figure21 0A856802-7E5C-54E3-93E6-FDCF2C03030E Figure 21. Ulnariajishou-biseriata sp. nov., girdle view, SEMA a dividing cell in girdle view B middle detail from A, note the mantles are hyaline in the central area C, D two apical details from A, showing both epivalve and hypovalve with associated three girdle bands (labelled B1 to B3) E, F two other apical details also show both epivalve and hypovalve with associated three girdle bands in a dividing cell (labelled B1 to B3). Scale bars: 20 μm (A); 2 μm (B–F). https://binary.pensoft.net/fig/867609 10.3897/phytokeys.228.101080.figure22 A0F046FF-94C3-5007-AB25-B50B86866B51 Figure 22. Ulnariajishou-biseriata sp. nov., girdle view, SEMA a frustule B–D details from A, showing a 4:3 configuration of girdle bands in a dividing cell. Scale bars: 20 μm (A); 2 μm (B–D). https://binary.pensoft.net/fig/867610 10.3897/phytokeys.228.101080.figure23 80E8496A-A388-52DB-9B29-8F23342DD7E5 Figure 23. Ulnariajishou-biseriata sp. nov., internal view, SEMA a valve with valvocopula B, C middle details from A, note serrated projections over each virga (C, arrows) D, E two apical details from A, note unornamented valvocopula at both apices (arrow respectively). Scale bars: 20 μm (A); 2 μm (B, D, E); 1 μm (C). https://binary.pensoft.net/fig/867611 10.3897/phytokeys.228.101080.figure24 7A4DC1A8-EBD1-5A71-84BA-89C9D775B33E Figure 24. Ulnariajishou-biseriata sp. nov., external view, SEMA a frustule in valve view B middle detail from A, showing central area flanked by a few marginal striae only on one side C, D two apical details from A, note a few serrated projections protruding over the ocellulimbus (C, three arrows) E a middle part showing the central area flanked by shortened striae on both sides F a middle part showing a rectangular central area. Scale bars: 20 μm (A); 2 μm (B, E, F); 1 μm (C, D). https://binary.pensoft.net/fig/867612 10.3897/phytokeys.228.101080.figure25 743C4118-A3D0-5D90-8E2F-9B07BF3E39DE Figure 25. Ulnariajishou-biseriata sp. nov., internal view, SEMA a complete valve B middle detail from A, note the rectangular central area C apical detail from A, note two rimoportulae present D other apical detail from A, note only one rimoportula present E, F two middle parts, note the variable central areas. Scale bars: 20 μm (A); 2 μm (B–F). https://binary.pensoft.net/fig/867613 Etymology. The epithet jishou-biseriata is formed from the city name Jishou and the term biseriate to reflect its type locality (Jishou) and its mostly biseriate striae. Ecology and distribution. The sampling site is close to Jishou City and many anthropogenic influences affect the environment and hence the diatoms. The diatom samples were scraped off of the stone surfaces. The following environmental parameters were measured in the field: Conductivity was 202.3 ± 1.2 μS∙cm-1, pH was 8.5 ± 0.1, and water temperature was 13.2 ± 0.3 °C. So far, its distribution is known only from the type locality. To sum up, U.jishou-biseriata lives on the stone surfaces of a mountainous river running through a small city. Discussion. Ulnariajishou-biseriata is characterized by its lanceolate valve outline, mostly biseriate striae, and very variable central areas. With respect to the valve outline, it is similar in some ways to U.ulnabiseriata, but the former has smaller and very variable central areas whereas the latter’s central areas are always a rectangular fascia (see Liu et al. 2017, p 249, figs 30–35). Taxon classification Plantae Licmophorales Ulnariaceae  Ulnaria pandurata-biseriata Bing Liu sp. nov. DC66DB16-3C10-5B26-8661-C5390F0D8CA0 Figs 26 , 27 , 28 , 29 Holotype. Slide JIUDIA202303, specimen circled on slide, illustrated as Fig. 26C. Registration. PhycoBank http://phycobank.org/103809 Type locality. China. Hunan province: Zhangjiajie National Forestry Park, Jinbian stream, at Shuirao Simen (29°20'36"N, 110°28'13"E, 467 m a.s.l.), collected by Bing Liu, December 29, 2015. Description. LM (Fig. 26). Valves panduriform with slightly constricted middle part and rostrate poles (Fig. 26A–P, see also Figs 27A, 28A, 29A). Valve dimensions (n = 36): length 37–60 μm, width 7–9.5 μm at centre, 8–10 μm at widest part. Sternum distinct, extending length of valve. Central area has two arrangements: an asymmetric hyaline region extending to both margins (Fig. 26A–M) or a hyaline area which extends to one margin with the other side bordered with a few short striae (Fig. 26N–P). Ghost striae are sometimes present (e.g., Fig. 26D, K) in the central area. Striae parallel, radiate only approaching each apex, and mostly opposite one another across sternum. Striae density 9–11 (often 10) in 10 μm. 10.3897/phytokeys.228.101080.figure26 9C03E616-6C09-5407-94AF-9A2D6CE11AA6 Figure 26. Ulnariapandurata-biseriata sp. nov., ×1000, LMA–P 16 valves exhibiting a size diminution series, note the panduriform valve outline and variable central areas C micrograph of holotype specimen. Scale bar: 10 μm. https://binary.pensoft.net/fig/867614 10.3897/phytokeys.228.101080.figure27 E83C8031-C291-52AF-805A-E89D7472C37D Figure 27. Ulnariapandurata-biseriata sp. nov., external view, SEMA a frustule in valve view B middle part detail from A, showing the central area with a few shortened marginal striae on one side C, D two apical details from A, note some partially triseriate striae (arrows) E another middle part showing the fascia-shaped central area F another apex, note a few serrated projections protruding over ocellulimbus. Scale bars: 10 μm (A); 2 μm (B–F). https://binary.pensoft.net/fig/867615 10.3897/phytokeys.228.101080.figure28 707B5960-7552-5408-B53C-8A40C10DA375 Figure 28. Ulnariapandurata-biseriata sp. nov., internal view, SEMA a complete valve B–D details from A, note some partially triseriate striae (arrows) E, F other apical details, note partially triseriate striae (arrows). Scale bars: 10 μm (A); 2 μm (B–F). https://binary.pensoft.net/fig/867616 10.3897/phytokeys.228.101080.figure29 672304E9-0CAC-54B5-8E2F-1F0571D25A16 Figure 29. Ulnariapandurata-biseriata sp. nov., internal view, SEMA a valve with a valvocopula B middle detail from A, note the unornamented middle portion of valvocopula (arrow) C, D apical details from A, note serrated projections over each virga (arrows) and valvocopula without ornamentation at each apex. Scale bars: 10 μm (A); 2 μm (B–D). https://binary.pensoft.net/fig/867617 SEM (Figs 27–29). Valve characterized by relatively wide virgae, interconnected with thin viminules, areolar closing plates having a few struts fixing them onto the areolar wall (Figs 27A–F, 28A–F, 29A–D). Valve with two types of mixed striae: one composed of a biseriate main part and a uniseriate minor part near sternum (usually 1 or 2 areolae), which describe most striae of valve (Figs 27A–F, 28A–F), and the other composed of a biseriate part, a triseriate part, and a uniseriate part near sternum (usually 1 or 2 areolae) (Figs 27C, D, 28B–F, two arrows, respectively). One rimoportula present at each pole, externally expressed as a simple hole (Fig. 27C, D, F), internally bilabiate, situated close to sternum (Fig. 28C–F). Ocellulimbus composed of ca.19 pervalvar and 9 transverse rows of porelli. A few serrated apical outgrowths protruding over the ocellulimbus (Fig. 27F). Valvocopula is a closed hoop, attached to the mantle interior, surrounding internal valve margin (Fig. 29A). Each valvocopula bears a mostly continuous row of poroids dividing the pars interior from pars exterior, located at the midline (Fig. 29A–D); lacking ornamentation at either apex (Fig. 29C, D). On its advalvar edge, valvocopula bears a row of serrated projections, each corresponding internally to a virga (Fig. 29C, D, three arrows respectively). Etymology. The epithet pandurata-biseriata is a combination of the terms pandurate and biseriate to reflect the valvar panduriform outline of the valve and its mostly biseriate striae. Ecology and distribution. The sampling site is situated close to the headwaters of Jinbian stream, which originates in the Zhangjiajie National Forestry Park. The diatom samples were scraped off of stone surfaces. The following environmental parameters were measured in the field: Conductivity was 102.7 ± 0.8 μS∙cm-1, pH was 8.5 ± 0.7 and water temperature was 8.7 ± 0.2 °C. So far, its distribution is known only from the type locality. To sum up, U.pandurata-biseriata lives on the stone surfaces of the headwaters of a mountainous stream. Discussion. Ulnariapandurata-biseriata is characterized by its panduriform valve outline, mostly biseriate striae, variable central areas, and smaller valves. Similar taxa include U.goulardii D.M. Williams, Potapova & C.E. Wetzel (see Williams 1986, p. 141, figs 27–36) and U.sangzhi-biseriata sp. nov (see below). All possess mostly biseriate striae, but they can be distinguished by the panduriform valve outline of U.pandurata-biseriata from the two latter’s lanceolate valve outline (for U.goulardii, see Williams 1986, p. 141, figs 27–36, as Synedragoulardii). Taxon classification Plantae Licmophorales Ulnariaceae  Ulnaria sangzhi-biseriata Bing Liu sp. nov. 9F2CEEEE-746C-5AAD-8A24-70264C149BBA Figs 30 , 31 , 32 , 33 , 34 Holotype. Slide JIUDIA202304, specimen circled on slide, illustrated as Fig. 30C. Registration. PhycoBank http://phycobank.org/103810. Type locality. China. Hunan province: Sangzhi County, Wudaoshui Town, Jinlong power station, Li River (29°43′7.1″N, 109°54′50.9″E, 398 m a.s.l.), collected by Bing Liu, September 30, 2015. Description. LM (Fig. 30). Valves linear-lanceolate with central margins sometimes very slightly constricted and capitate to sub-capitate apices (Fig. 30A–I, see also Figs 32A, E, 33A, 34A, E). Valve dimensions (n = 22): length 49–91 μm, width 6.5–8.2 μm at centre. Sternum discernible, extending length of valve. Central area rectangular or square. Ghost striae present in central area (e.g., Fig. 30B–D). Striae parallel, radiate only at poles, and mostly opposite each other across sternum. Stria density 10–12 (often 11) in 10 μm. 10.3897/phytokeys.228.101080.figure30 8390E25E-CB75-59CF-B21F-2BAC9CDCF62D Figure 30. Ulnariasangzhi-biseriata sp. nov., ×1000, LMA–I nine valves exhibiting a size diminution series, note linear-lanceolate valve outline, rectangular central area and capitate to sub-capitate apices C micrograph of holotype specimen. Scale bar: 10 μm. https://binary.pensoft.net/fig/867618 SEM (Figs 31–34). Frustule rectangular in girdle view (Fig. 31A). Epivalve associated with valvocopula and three copulae (Fig. 31C, D, labelled B1–B4, B1 = valvocopula). Valvocopula is a closed hoop, attached to the mantle interior, surrounding the valve internal margin (Fig. 32A, E). The valvocopula has a mostly continuous row of poroids dividing pars interior from pars exterior, located at the midline (Fig. 26B–D). On its advalvar edge there is a row of serrated projections, each corresponding internally to a virga (Figs 31B, 32B–D, F, two arrowheads respectively), ornamentation is lacking at either pole (Fig. 32C, D, F). Valve face and mantle intersect almost at right angle (Fig. 33A–F). Central hyaline area rectangular or square (Figs 33B, E, 34B, F). Valve characterized by a series of relatively wide virgae, interconnected with thin viminules and closing plates affixed with a few struts to the areolar wall (Figs 32A–F, 33B–F, closing plate see Fig. 33F, two wavy arrows). Valve has two types of mixed striae: most striae of the valve are composed of a biseriate main part and a uniseriate minor part near the sternum (usually 1 or 2 areolae, Figs 33B–F, 34B–D, F), and the rest are composed of a biseriate part, a triseriate part, and a uniseriate part near sternum (usually 1 or 2 areolae) (Fig. 34C, D, two arrows respectively). Ocellulimbus composed of ca. 18 pervalvar and 7 transverse rows of porelli. A few serrated apical outgrowths protruding over each ocellulimbus (Fig. 33C, D, F, two arrows respectively). Striae continue onto mantle, absent in the centre (Fig. 31B). One rimoportula at each pole (Figs 33C, D, F, 34C, D), externally expressed as a simple hole in different shapes (Fig. 33C, D, F), internally bilabiate, situated close to sternum (Fig. 34C, D). 10.3897/phytokeys.228.101080.figure31 1E49D84D-52AC-5D62-BDC7-F3836EE66BF7 Figure 31. Ulnariasangzhi-biseriata sp. nov., girdle view, SEMA a partly collapsed frustule B middle part from A, note variable central mantles and serrated projections of valvocopula (three arrowheads) C, D two apical details from A, showing four girdle bands associating the epivalve (labelled B1–B4). Scale bars: 10 μm (A); 2 μm (B–D). https://binary.pensoft.net/fig/867619 10.3897/phytokeys.228.101080.figure32 81F8930E-2171-5B1E-A3B9-081DED869727 Figure 32. Ulnariasangzhi-biseriata sp. nov., internal view, SEMA a valve with a valvocopula B middle part from A, note the serrated projections (two arrowheads) C, D two apical details from A, note the closed nature of valvocopula and serrated projections (arrowheads) E another valve with a valvocopula F apical detail from E, note the serrated projections (two arrowheads). Scale bars: 10 μm (A, E); 2 μm (B–D, F). https://binary.pensoft.net/fig/867620 10.3897/phytokeys.228.101080.figure33 B7328A5A-B7AF-505B-873F-C06F0740E9A4 Figure 33. Ulnariasangzhi-biseriata sp. nov., external view, SEMA a complete valve B middle detail from A, note rectangular central area C, D two apical details from A, note a few serrated projections protruding over the ocellulimbus (arrows) E another middle part showing rectangular central area with ghost striae F another apical detail, note a few serrated projections (two arrows) and the closing plates (two curved arrows). Scale bars: 10 μm (A); 2 μm (B, E); 1 μm (C, D, F). https://binary.pensoft.net/fig/867621 10.3897/phytokeys.228.101080.figure34 5F1297EA-220D-5537-B62B-3A8CEBC7631F Figure 34. Ulnariasangzhi-biseriata sp. nov., internal view, SEMA a complete valve B middle detail from A, showing the central area C, D two apical details from A, note part triseriate striae (arrows) E another complete valve F middle detail from E. Scale bars: 10 μm (A, E); 2 μm (B–D, F). https://binary.pensoft.net/fig/867622 Etymology. The epithet sangzhi-biseriata is a combination of Sangzi and the term biseriate to reflect its type locality (Sangzi) and its mostly biseriate striae. Ecology and distribution. The sampling site is near Wudaoshui Town, and some human activities may have affected the environment and hence the diatoms. The diatom samples were scraped off of the stone surfaces. The following environmental parameters were measured in the field: Conductivity was 219.3 ± 1.2 μS∙cm-1, pH was 8.5 ± 0.2 and water temperature was 17.9 ± 0.3 °C. To sum up, U.sangzhi-biseriata lives on the stone surfaces of a mountainous river flowing away from the Town. So far, its distribution is known only from the type locality. Discussion. Ulnariasangzhi-biseriata is characterized by its linear-lanceolate valve outline, mostly biseriate striae, rectangular or square central area, and capitate to sub-capitate apices. It is similar to U.goulardii which has a more constricted valve central margin. Moreover, the former has capitate to sub-capitate apices whereas U.goulardii has rostrate apices (see Williams 1986, p. 141, figs 27–36, as Synedragoulardii). Taxon classification Plantae Licmophorales Ulnariaceae  Ulnaria wuling-biseriata Bing Liu sp. nov. 96A4A27C-9D80-52D2-B6EB-4C0B0A645655 Figs 35 , 36 , 37 , 38 Holotype. Slide JIUDIA202305, specimen circled on slide, illustrated as Fig. 35A. Registration. PhycoBank http://phycobank.org/103811 Type locality. China. Hunan province: Zhangjiajie National Forestry Park, Jinbian stream, at Shuirao Simen (29°20'36"N, 110°28'13"E, 467 m a.s.l.), collected by Bing Liu, December 29, 2015. Description. LM (Fig. 35). Valves linear with abruptly tapering rostrate to sub-capitate apices (Fig. 35A–J, see also Figs 36A, E, 37A, E). Valve dimensions (n = 15): length 160–200 μm, width 6.5–8 μm at centre. Sternum discernible, mostly regular, occasionally irregular (e.g., Fig. 35D), extending length of valve. Central area apically rectangular or trapezoid. Ghost striae sometimes present in central area (e.g., Fig. 35C, I). Striae parallel, radiate only at each pole, and mostly opposite across sternum. Stria density 10–11 in 10 μm. 10.3897/phytokeys.228.101080.figure35 225B1FC0-7977-5444-B947-23EE83B16F92 Figure 35. Ulnariawuling-biseriata, sp. nov., ×630, LMA–J ten valves exhibiting a size diminution series, note linear valve outlines, rostrate apices, and rectangular hyaline central area A micrograph of holotype specimen. Scale bar: 20 μm. https://binary.pensoft.net/fig/867623 10.3897/phytokeys.228.101080.figure36 F9EAA884-39AA-5686-B3C7-26D714562B40 Figure 36. Ulnariawuling-biseriata, sp. nov., external view, SEMA a complete valve B middle detail from A, showing the rectangular central area C, D two apical details of A, note some uniseriate striae at the apices E another complete valve F middle detail from E, showing a trapezoidal central area. Scale bars: 20 μm (A, E); 2 μm (B–D, F). https://binary.pensoft.net/fig/867624 10.3897/phytokeys.228.101080.figure37 9879FCEA-EFAE-5883-9B10-B46CC4F8AFEF Figure 37. Ulnariawuling-biseriata, sp. nov., internal view, SEMA a complete valve B middle detail from A, showing the rectangular central area C, D two apical details from A. E Another complete valve F middle detail from E showing the trapezoidal central area. Scale bars: 20 μm (A, E); 2 μm (B–D, F). https://binary.pensoft.net/fig/867625 SEM (Figs 36–38). Valves mostly with mixed striae, each composed of a biseriate main part and a uniseriate minor part (including several areolae) near sternum (Figs 36B–D, F, 37B–D, F). But some uniseriate striae occurring near each apex (Fig. 36C, D). One rimoportula at each pole, externally expressed as a simple hole (Fig. 36C, D), internally bilabiate, situated close to sternum (Figs 37C, D, 38D). Ocellulimbus composed of ca. 24 pervalvar and 8 transverse rows of porelli. Valvocopula a closed hoop (Fig. 38A), with a mostly continuous row of poroids dividing pars interior from pars exterior, located at the midline (Fig. 38B, C, E). A row of serrated projections is located on its advalvar edge, each corresponding internally to a virga (Fig. 38B, C), unornamented at both poles (Fig. 38C, F). 10.3897/phytokeys.228.101080.figure38 030EA2C1-8F9E-5BEC-AFD0-8C8B61EBE413 Figure 38. Ulnariawuling-biseriata, sp. nov., internal view, SEMA a valve with a valvocopula B middle detail from A. C, D two apical details of A, note the valvocopula unornamented at each apex E, F details of the valvocopula, note its closed nature and the shelf-like projection (F, arrow). Scale bars: 20 μm (A); 2 μm (B–F). https://binary.pensoft.net/fig/867626 Etymology. The epithet "wuling-biseriata" is a combination of Wuling and the term biseriate to reflect its type locality (Wuling Mountains) and its mostly biseriate striae. Ecology and distribution. Ulnariawuling-biseriata was commonly found in the surface sediment collected in Jinbian stream with U.pandurata-biseriata and U.ulnabiseriata. Thus, U.wuling-biseriata lives on the stone surfaces of the headwaters of a mountainous stream. So far, its distribution is known only from the type locality. Discussion. Ulnariawuling-biseriata is characterized by its linear valve outline, mostly biseriate striae, rectangular or trapezoid central area, and rostrate to sub-capitate apices. The apices of Ulnariaulnavar.spathulifera Aboal sometimes have an inflation before tapering to form subrostrate to rostrate ends whereas U.wuling-biseriata does not have this inflation, i.e., its apex is not spatulate. Moreover, the valves of U.ulnavar.spathulifera are wider than the ones of U.wuling-biseriata (8–9 μm vs 6.5–8 μm) and the former has lower stria density than the latter (9–10 in 10 μm vs 10–11 in 10 μm) (see Morales et al. 2007, p. 34, as Synedraulnavar.spathulifera). Taxon classification Plantae Licmophorales Ulnariaceae  Ulnaria blancoi Bing Liu sp. nov. A3CC9D81-1635-55D8-8EF7-BCA7DDF68E4B Figs 39 , 40 , 41 , 42 , 43 Holotype. Slide JIUDIA202306, specimen circled on slide, illustrated as Fig. 39A. Registration. PhycoBank http://phycobank.org/103812. Type locality. China. Qinghai province: Menyuan County, an unnamed river, at a sampling location named Kengtan (37°27'28"N, 101°23'15"E, 2940 m a.s.l.), collected by Bing Liu, July 18, 2019. Description. LM (Fig. 39). Valves lanceolate with rostrate to sub-capitate apices (Fig. 39A–M, see also Figs 40A, C, 41A, 42A). Valve dimensions (n = 24): length 104–236 μm, width 4.6–6.8 μm at centre. Sternum distinct, extending length of valve. Central area very variable: hyaline region extending to both margins forming rectangular fascia (e.g., Fig. 39A, see also Fig. 41B). It can be circumscribed by both short marginal striae and isolated areolae (e.g., Fig. 39D–F, see also Fig. 40D), nearly absent (Fig. 39J, see also Fig. 42B) or completely lacking (see Fig. 40A, B). Striae parallel, radiate only approaching each apex, some opposite each other, and others alternate across the sternum. Stria density 10–13 in 10 μm, increasing near each apex. 10.3897/phytokeys.228.101080.figure39 0CE6C8AB-FC03-5202-A72B-4F33092A4F45 Figure 39. Ulnariablancoi sp. nov., ×630, LMA–M thirteen valves exhibiting a size diminution series, note the lanceolate valve outline and small variable central areas A micrograph of holotype specimen. Scale bar: 20 μm. https://binary.pensoft.net/fig/867627 10.3897/phytokeys.228.101080.figure40 01A5350B-740D-51AC-8BEC-D3582ABC23C2 Figure 40. Ulnariablancoi sp. nov., external view, SEMA, C two complete valves, note central area present or absent B middle part from A, note central area completely absent D middle part from C, note small central area flanked by marginal short striae E, F two apical details, note two horn-like projections protruding over the ocellulimbus (E, two arrows). Scale bars: 20 μm (A, C); 2 μm (B, D, F); 1 μm (E). https://binary.pensoft.net/fig/867628 10.3897/phytokeys.228.101080.figure41 79F1117B-742A-57F2-A5A6-DC80ECC6AECD Figure 41. Ulnariablancoi sp. nov., internal view, SEMA a complete valve B middle part detail from A, note rectangular central area C, D two half parts from A. E, F Two apical details from A. Scale bars: 20 μm (A); 4 μm (B–D); 2 μm (E, F). https://binary.pensoft.net/fig/867629 10.3897/phytokeys.228.101080.figure42 FDE4659B-0FF0-5F8D-B4F3-561EF44F573B Figure 42. Ulnariablancoi sp. nov., internal view, SEMA a complete valve B middle part from A, note the very small central area C, D other valve middle part details, note variable central areas. Scale bars: 20 μm (A); 2 μm (B–D). https://binary.pensoft.net/fig/867630 SEM (Figs 40–43). Valve characterized by a series of relatively wide virgae, interconnected with vimines and closing plates attached with a few struts to each areolar wall (Figs 40A–F, 41A–F, 42A–D, closing plates see Fig. 43C). Striae uniseriate. Each stria on both sides opposite or alternate, areolae gradually apically elongated from sternum to mantle (Figs 40B, D, 41B, 42B–D). Central area completely lacking (Fig. 40A, B), hyaline region circumscribed by both short marginal striae and isolated areolae (Figs 40C, 42B–D), or hyaline area extending to both margins (Fig. 41B). Ocellulimbus composed of ca. 16 pervalvar and 7 transverse rows of porelli. Two horn-like projections protruding over the ocellulimbus (Fig. 40E, two arrows). One rimoportula located at each pole, externally expressed as a simple hole (Fig. 40E, F), internally bilabiate, situated close to sternum at an angle (Fig. 41E, F). Valvocopula a closed hoop, surrounding the valve internal margin (Fig. 43A). Valvocopula bearing a mostly continuous row of poroids dividing pars interior from pars exterior, located at the midline (Fig. 43B–F), lacking ornamentation at both poles (Fig. 43E, F). On its advalvar edge, valvocopula has a row of serrated projections, each corresponding internally to a virga (Fig. 43B–E). 10.3897/phytokeys.228.101080.figure43 BEBD5A83-2043-5459-922E-F8E8FCB74B45 Figure 43. Ulnariablancoi sp. nov., internal view, SEMA a valve with valvocopula B middle part detail from A. C Detail of valvocopula, note closing plates D–F apical details from A. Scale bars: 20 μm (A); 2 μm (B–F). https://binary.pensoft.net/fig/867631 Etymology. Named after the Spanish diatomist, Dr. Saúl Blanco. Ecology and distribution. The sampling site is located in the plateau which belongs to the highland continental climate zone. The diatom samples were scraped off of the stone surfaces. The following environmental parameters were measured in the field: Conductivity was 448.3 ± 0.5 μS∙cm-1, pH was 8.3 ± 0.1 and water temperature was 11.9 ± 0.5 °C. To sum up, U.blancoi lives on the stone surfaces of a plateau river. So far, its distribution is known only from the type locality. Discussion. Ulnariablancoi is characterized by its lanceolate valve outline, uniseriate striae, very variable central areas, and rostrate to sub-capitate apices. It differs from U.vitrea (Kützing) E. Reichardt by its much longer valves (104–236 μm vs 90–120 μm) and its often-present central area whereas U.vitrea often lacks central area (see Williams 2020, p. 4). Ulnariasplendens (Kützing) D.M. Williams et Van de Vijver is wider (5–10 μm vs 4.6–6.8 μm) and its stria density is lower than that of U.blancoi (6–10 striae in 10 μm vs 10–13 striae in 10 μm). Moreover, U.blancoi often has sub-capitate apices whereas U.splendens has rostrate apices (see Williams and Van de Vijver 2021, p. 167, figs 1–10). Taxon classification Plantae Licmophorales Ulnariaceae  Ulnaria menyuanensis Bing Liu sp. nov. 006A480B-45CD-5476-A234-68D0D837E060 Figs 44 , 45 , 46 , 47 Holotype. Slide JIUDIA202307, specimen circled on slide, illustrated as Fig. 44D. Registration. PhycoBank http://phycobank.org/103813 Type locality. China. Qinghai province: Menyuan County, an unnamed river, at a sampling location named Kengtan (37°27'28"N, 101°23'15"E, 2940 m a.s.l.), collected by Bing Liu, July 18, 2019. Description. LM (Fig. 44). Valves lanceolate (fusiform) with cuneate to rostrate apices (Fig. 44A–J, see also Figs 45A, 46A). Valve dimensions (n = 31): length 60–104 μm, wide 5–7 μm at centre. Sternum distinct, extending length of valve. Central area not clearly visible due to presence of many ghost striae (Fig. 44A–J, see also Figs 45B, E, F, 46B, E, F). Striae parallel, radiate only approaching each pole, 12–14 in 10 μm, denser near poles. Striae on both sides of sternum, some alternate, some opposite. 10.3897/phytokeys.228.101080.figure44 CC2E1C8A-83E2-5E4E-863C-2019BD3AB3CE Figure 44. Ulnariamenyuanensis sp. nov., ×1000, LMA–J ten valves exhibiting a size diminution series, note the lanceolate valve outline and distinctive ghost striae in the middle regions of the valves D micrograph of holotype specimen. Scale bar: 10 μm. https://binary.pensoft.net/fig/867632 10.3897/phytokeys.228.101080.figure45 EAD78EA6-2F61-5F2B-853E-B0D551DA6606 Figure 45. Ulnariamenyuanensis sp. nov., external view, SEMA a complete valve B middle part detail from A, note the shallow grooves and short striae at the central region C, D two apical details from A. E, F Other middle parts, note the shallow grooves and short striae. Scale bars: 10 μm (A); 2 μm (B–F). https://binary.pensoft.net/fig/867633 SEM (Figs 45–47). Valve characterized by a series of relatively wide virgae, interconnected with vimines and closing plates affixed with a few struts to each areolar wall (Figs 45A–F, 46A–F, closing plate see Fig. 47D, F). Central area circumscribed by both short marginal striae and isolated areolae (Figs 45B, E, F, 46B, E, F). Unperforate internal shallow grooves distinct in central area (e.g., Fig. 46B, E, F). Ocellulimbus composed of ca. 13 pervalvar and 7 transverse rows of porelli. Striae uniseriate. Areolae not apically elongated from sternum to mantle (Fig. 46B–F). One rimoportula located at each pole, externally expressed as a simple hole (Fig. 45C, D), internally bilabiate, situated close to sternum (Fig. 46C, D). Valvocopula a closed hoop, surrounding the valve internal margin (Fig. 47A). Valvocopula bearing a mostly continuous row of poroids dividing pars interior from pars exterior, located at midline (Fig. 47B, C, E), lacking ornamentation at both poles (Fig. 47D, F). On its advalvar edge, valvocopula has a row of serrated projections, each corresponding internally to a virga (Fig. 47B, C, E, three arrows, respectively). 10.3897/phytokeys.228.101080.figure46 18F3FDAF-2386-5331-8711-FF0E6A0C04CC Figure 46. Ulnariamenyuanensis sp. nov., internal view, SEMA a complete valve B middle part from A, note shallow grooves and short striae C, D two apical details from A, note the bilabiate rimoportulae and apical pore fields E, F other middle parts, note shallow grooves and short striae. Scale bars: 10 μm (A); 2 μm (B–F). https://binary.pensoft.net/fig/867634 10.3897/phytokeys.228.101080.figure47 B5747319-288E-5C67-88F6-84C7D951C71D Figure 47. Ulnariamenyuanensis sp. nov., internal view, SEMA a valve with associated valvocopula B middle part detail from A, note serrated projections (three arrows) C, D apical details from A, note serrated projections (C, three arrows) and closing plates (D, two arrows) E, F details from other apex from A, note serrated projections (E, three arrows) and closing plates (F, two arrows). Scale bars: 10 μm (A); 5 μm (B, C, E); 2 μm (D, F). https://binary.pensoft.net/fig/867635 Etymology. Named after Menyuan County, where the species was found. Ecology and distribution. Ulnariamenyuanensis was commonly found in the surface sediment collected in Kengtan with U.blancoi. Thus, U.menyuanensis lives on the stone surfaces of a plateau river. So far, its distribution is known only from the type locality. Discussion. Ulnariamenyuanensis is characterized by its fusiform valve outline, the presence of distinct ghost striae, and cuneate to rostrate apices. It differs from U.ramesii (Héribaud) T. Ohtsuka by the latter’s linear-lanceolate valve outline (see Morales et al. 2007, p. 73, figs 87–94, as Synedraulnavar.ramesi) and differs from U.oxyrhynchus (Kützing) Aboal by the latter’s acute apices (see Morales et al. 2007, p. 65, figs 62–67, as Synedraulnavar.oxyrhynchus). Ulnariaverhaegeniana Van de Vijver, De Haan, Mertens & Cocquyt has parallel margins almost to valve apices while U.menyuanensis has lanceolate valve outline and possesses distinct ghost striae (see Van de Vijver et al. 2017, p. 222 for comparison). Taxon classification Plantae Licmophorales Ulnariaceae  Ulnaria neobiceps Bing Liu sp. nov. AEFF919F-8334-5F81-B2E4-38D9EC4E5846 Figs 48 , 49 , 50 , 51 , 52 , 53 Holotype. Slide JIUDIA202308, specimen circled on slide, illustrated as Fig. 48A. Registration. PhycoBank http://phycobank.org/103814. Type locality. China. Qinghai province: Menyuan County, an unnamed river, at a sampling location named Kengtan (37°27'28"N, 101°23'15"E, 2940 m a.s.l.), collected by Bing Liu, July 18, 2019. Description. LM (Fig. 48). Valves linear-lanceolate with distinct capitate apices (Fig. 48A–K, see also Figs 49A, 50A). Valve dimensions (n = 23): length 202–307 μm, width 4.5–6.7 μm at centre. Sternum distinct, extending length of valve. Central area very variable: hyaline region extending to both margins (e.g., Fig. 48F, K), can be circumscribed by both short marginal striae and isolated areolae (e.g., Fig. 48B, C, G, J), nearly absent (Fig. 48H) or completely lacking (Fig. 48A, D, E, I). Striae parallel, radiate only approaching each pole, 9–11 in 10 μm, increasing near each pole. Striae on both sides of sternum, some opposite each other, and others alternate. 10.3897/phytokeys.228.101080.figure48 AD8D43A9-B18A-557C-BFB1-BBB5E6948E43 Figure 48. Ulnarianeobiceps sp. nov., ×400, LMA–K eleven valves exhibiting a size diminution series, note the linear-lanceolate valve outline and variable central areas A micrograph of holotype specimen. Scale bar: 20 μm. https://binary.pensoft.net/fig/867636 10.3897/phytokeys.228.101080.figure49 E4F65E2C-BA7E-5F71-A6EA-55BB04F35B99 Figure 49. Ulnarianeobiceps sp. nov., external view, SEMA a complete valve B middle part detail from A, note central area complete absent C–F apical details from A, note the capitate apices. Scale bars: 20 μm (A); 2 μm (B); 3 μm (C–E); 1 μm (F). https://binary.pensoft.net/fig/867637 10.3897/phytokeys.228.101080.figure50 BA794068-15CC-5DE1-858D-61DE29D44A08 Figure 50. Ulnarianeobiceps sp. nov., internal view, SEMA a complete valve B middle part detail from A, note the very small central area (arrow) C, E two poles from A, note that valve margins do not constrict near the capitate apices (two arrows, respectively) D, F two apical details, note the capitate apices and apical pore field. Scale bars: 20 μm (A); 2 μm (B–F). https://binary.pensoft.net/fig/867638 SEM (Figs 49–53). Valve characterized by a series of relatively wide virgae and interconnected with vimines (Fig. 49B–F). Central area completely lacking (Fig. 49B), hyaline area circumscribed by both short marginal striae and isolated areolae (Figs 50B, 51A, C, D), or hyaline area extending to both margins (Fig. 51B). Striae uniseriate, on both sides of sternum, opposite or alternate, areolae gradually become elongated from sternum to mantle (Figs 50B–F, 51A–D). Ocellulimbus composed of ca. 24 pervalvar and 8 transverse rows of porelli. Two horn-like projections protruding over the ocellulimbus (Fig. 52D, two arrows). One rimoportula located at each pole, externally expressed as a simple hole (Fig. 49F), internally bilabiate, situated close to sternum at an angle (Fig. 50D, F). Valvocopula closed, surrounding the valve internal margin (Fig. 52A), bearing a mostly continuous midline row of poroids dividing pars interior from pars exterior (Figs 52B–F, 53A–F), lacking ornamentation at both poles (Figs 52D, F, 52C–F). On its advalvar edge, valvocopula has a row of serrated projections, each corresponding internally to a virga (Fig. 52B, C, E). Shelf-like projections present at pars interior of each apex (Fig. 53C–F, two arrows, respectively). 10.3897/phytokeys.228.101080.figure51 5FCF553F-5493-5FBD-9EF8-661CB5F5D867 Figure 51. Ulnarianeobiceps sp. nov., internal view, SEMA–D four middle valve parts showing very variable central areas. Scale bars: 2 μm (A–D). https://binary.pensoft.net/fig/867639 10.3897/phytokeys.228.101080.figure52 71119EBC-855F-5B5B-98D6-7BAEF1B84F7A Figure 52. Ulnarianeobiceps sp. nov., internal view, SEMA a valve with valvocopula B–F details from A, showing the valvocopula structure, note two horn-like projections protruding over ocellulimbus. Scale bars: 20 μm (A); 3 μm (B, C, E); 2 μm (D, F). https://binary.pensoft.net/fig/867640 10.3897/phytokeys.228.101080.figure53 50E0834C-EAA2-584E-ABE3-12CFCBAC8C71 Figure 53. Ulnarianeobiceps sp. nov., valvocopula, SEMA a complete valvocopula B–D details from A, showing row of poroids interrupted in the middle and shelf-like projection at each apex (C, D, two arrows respectively) E, F other two apical details of valvocopula have the same apical structure. Scale bars: 20 μm (A); 3 μm (B); 2 μm (C–F). https://binary.pensoft.net/fig/867641 Etymology. The epithet biceps has been occupied by Ulnariabiceps (Kützing) Compère, so here the epithet neobiceps is used, which is a combination of neo (new) and biceps (two capitate) reflecting its two distinctly capitate poles. Ecology and distribution. Ulnarianeobiceps, U.blancoi, and U.menyuanensis were commonly found in the same sampling site of Kengtan. Thus, U.neobiceps lives on the stone surfaces of a plateau river. So far, its distribution is known only from the type locality. Discussion. Ulnarianeobiceps is characterized by its linear-lanceolate valve outline, variable central area, distinctly capitate apices, and long and slender valve. Both U.neobiceps and U.capitata (Ehrenberg) Compère have capitate apices, but the apices of U.capitata are rhomboid-capitate (see Morales et al. 2007, p. 49, figs 13–17; p. 51, figs 18–20, as Synedracapitata) whereas the apices of U.neobiceps are rounded-capitate. Moreover, U.neobiceps has very variable central area while U.capitata lacks central area. Taxon classification Plantae Licmophorales Ulnariaceae  Ulnaria chengduoensis Bing Liu sp. nov. 82643DCA-64CC-50BB-A3EA-F40492A5647F Figs 54 , 55 , 56 Holotype. Slide JIUDIA202309, specimen circled on slide, illustrated as Fig. 54A. Registration. PhycoBank http://phycobank.org/103815. Type locality. China. Qinghai province: Chengduo County, Baima River, at a sampling location (33°22'21"N, 97°0'18"E, 3690 m a.s.l.), collected by Bing Liu, July 22, 2019. Description. LM (Fig. 54). Valves linear with rostrate apices (Fig. 54A–P, see also Figs 55E, 56A–C). Valve dimensions (n = 51): length 42–66 μm, width 6–8 μm at centre. Sternum distinct, extending length of valve. Central area not clearly visible due to presence of ghost striae (Fig. 54A–G, I–K, M) or completely lacking (Fig. 54H, L, N–P). Striae parallel, radiate only approaching each pole, 12–15 in 10 μm. Across sternum some striae opposite one another, others alternate. 10.3897/phytokeys.228.101080.figure54 D14054A2-E7DC-5031-A494-585FC0FB14A7 Figure 54. Ulnariachengduoensis sp. nov., ×1000, LMA–P sixteen valves exhibiting a size diminution series, note the linear-lanceolate valve outline and variable central areas A micrograph of holotype specimen. Scale bar: 10 μm. https://binary.pensoft.net/fig/867642 SEM (Figs 55, 56). Valve characterized by a series of relatively wide virgae, interconnected with vimines (Fig. 55B–D). Striae uniseriate, areolae often apically elongated (Fig. 56E). Central area variable: a hyaline area circumscribed by both short marginal striae and isolated areolae (Figs 55B, 56A, B), or completely absent (Figs 55F, 56E). One rimoportula located at each pole, externally expressed as a simple hole (Fig. 55C, D), internally bilabiate, situated close to sternum (Fig. 56D, F). Ocellulimbus composed of ca. 12 pervalvar and 9 transverse rows of porelli (Fig. 56F). 10.3897/phytokeys.228.101080.figure55 0534649E-CE39-5043-A146-07A78C521E18 Figure 55. Ulnariachengduoensis sp. nov., external view, SEMA a broken valve B middle part detail from A, note the central area flanked by marginal short striae C, D two apical details from A, note the rostrate apices E a complete valve F middle part detail from E, note central area absent. Scale bars: 10 μm (A, E); 2 μm (B–D, F). https://binary.pensoft.net/fig/867643 10.3897/phytokeys.228.101080.figure56 EFC80D58-9B4F-5814-A1C6-DDF679BAF4A7 Figure 56. Ulnariachengduoensis sp. nov., internal view, SEMA–C three complete valves, note the linear-lanceolate valve outlines and variable central areas D–F details from C, note rostrate apices and absent central area. Scale bars: 10 μm (A–C); 2 μm (D, E); 1 μm (F). https://binary.pensoft.net/fig/867644 Etymology. Named after Chengduo County, where this species was found. Ecology and distribution. Epilithic in a plateau river. The following environmental parameters were measured in the field: Conductivity was 422.7 ± 1.3 μS∙cm-1, pH was 8.2 ± 0.1 and water temperature was 12.2 ± 0.5 °C. So far, its distribution is known only from the type locality. Discussion. Ulnariachengduoensis is characterized by its linear valve outline, variable central area, narrow rostrate valve apices. It differs from U.ramerii and U.verhaegeniana by its variable central area, i.e., it may completely lack a central area whereas U.ramerii always possesses an ellipsoid to rectangular central area (see Morales et al. 2007, p. 73, figs 87–94, as Synedraulnavar.ramesi) and U.verhaegeniana always has a large, apically elongated, rectangular central area (see Van de Vijver et al. 2017, p. 223, figs 1–13). Taxon classification Plantae Licmophorales Ulnariaceae  Ulnaria qinghainensis Bing Liu sp. nov. DBEF86D6-86F0-551A-BC60-6131B3ADF5CF Figs 57 , 58 , 59 , 60 Holotype. Slide JIUDIA202310, specimen circled on slide, illustrated as Fig. 57C. Registration. PhycoBank http://phycobank.org/103816. Type locality. China. Qinghai province: Chengduo County, Baima River, at a sampling location (33°22'21"N, 97°0'18"E, 3690 m a.s.l.), collected by Bing Liu, July 22, 2019. Description. LM (Fig. 57). Frustule rectangular in girdle view (Fig. 57A). Valves linear-lanceolate with sub-capitate apices (Fig. 57B–N, see also Figs 58A, 59A). Valve dimensions (n = 35): length 88–223 μm, width 3.1–5.0 μm at centre. Sternum distinct, extending length of valve. Central area completely absent. Striae parallel, radiate at apices, and mostly opposite one another across sternum. Stria density 9–11 in 10 μm. 10.3897/phytokeys.228.101080.figure57 F497CBF0-498E-55BD-B298-C26514877AD2 Figure 57. Ulnariaqinghainensis sp. nov., ×630, LMA a frustule in girdle view B–N thirteen valves exhibiting a size diminution series, note the narrowly lanceolate valve outlines and absent central areas B micrograph of holotype specimen. Scale bar: 20 μm. https://binary.pensoft.net/fig/867645 10.3897/phytokeys.228.101080.figure58 4A6AD182-E74B-55D5-88EB-4108CC4EBB2E Figure 58. Ulnariaqinghainensis sp. nov., external view, SEMA a valve with valvocopula B detail of middle part from A, note absent central area C–F two poles from A, note two horn-like projections (D, two arrows) and row of poroids terminating before each apex of valvocopula (E, F, wavy arrow respectively). Scale bars: 20 μm (A); 4 μm (B–F). https://binary.pensoft.net/fig/867646 SEM (Figs 58–60). Valve characterized by a series of relatively wide virgae, interconnected with vimines (Fig. 58B–F). Striae uniseriate. Stria mostly opposite across sternum, equidistant until radiate at poles, areolae often apically elongated, especially near the mantle (Figs 58B–F, 59B, C, E). Central area completely absent (Figs 58B, 59B). Ocellulimbus composed of ca. 18 pervalvar and 9 transverse rows of porelli. Two horn-like projections protruding over the ocellulimbus (Fig. 58D, two arrows). One rimoportula located at each pole, externally expressed as a simple hole (Fig. 58D, F), internally bilabiate, situated close to sternum (Fig. 59D, F). Valvocopula closed, surrounding the valve internal margin (Fig. 60A), bearing a mostly continuous row of poroids dividing pars interior from pars exterior, located at the midline (Fig. 60B–F), lacking ornamentation at both poles (Fig. 60D, F). On its advalvar edge, valvocopula has a row of serrated projections, each corresponding internally to a virga (Fig. 60B, C, E). 10.3897/phytokeys.228.101080.figure59 22EAF721-F695-54FF-9959-E81EA7807649 Figure 59. Ulnariaqinghainensis sp. nov., internal view, SEMA a complete valve B middle part from A, note central area is absent C–F two apical details from A. Scale bars: 20 μm (A); 4 μm (B, C, E); 1 μm (D, F). https://binary.pensoft.net/fig/867647 10.3897/phytokeys.228.101080.figure60 3EE9D4DB-8673-52F4-9996-A5AA5CCDC505 Figure 60. Ulnariaqinghainensis sp. nov., internal view, SEMA valve with valvocopula B middle part from A. C–F Two apical details from A. Scale bars: 20 μm (A); 4 μm (B, C, E); 1 μm (D, F). https://binary.pensoft.net/fig/867648 Etymology. Named after Qinghai province, where this species was found. Ecology and distribution. Epilithic in a plateau river. Ulnariaqinghainensis and U.chengduoensis were commonly found in the same sampling site. The environmental parameters were measured in the field and the results are given in the description of the former taxon above. So far, its distribution is known only from the type locality. Discussion. Ulnariaqinghainensis is characterized by its linear-lanceolate valve outline, lacking central area, sub-capitate apices, and slender valves. It differs from U.obtusa (W. Smith) E. Reichardt by its narrower valves (3.1–5.0 μm vs 5–8 μm) and its much higher stria density (9–11 in 10 μm vs 3–4 in 10 μm) (see Williams and Van de Vijver 2021, p. 175). Taxon classification Plantae Licmophorales Ulnariaceae  Ulnaria fanjingensis Bing Liu sp. nov. FE58F79A-717B-52AB-BFB5-BCEDE4E737A7 Figs 61 , 62 , 63 , 64 , 65 , 66 Holotype. Slide JIUDIA202311, specimen circled on slide, illustrated as Fig. 62D. Registration. PhycoBank http://phycobank.org/103817. Type locality. China. Guizhou province: Fanjing Mountain National Nature Reserve, Heiwang river, near Mile Daochang (27°49'10"N, 108°46'18"E, 494 m a.s.l.), collected by Bing Liu, December 31, 2015. Description. LM (Figs 61, 62). Living cells with numerous plate-like chromatophores (Fig. 61A–F, note that these cells may be in an unhealthy condition). Valves lanceolate, narrow, with rostrate to sub-capitate apices (Figs 61E, F, 62A–N). Valve dimensions (n = 56): length 165–291 μm, width 4.8–6.3 μm at centre. Sternum distinct, extending length of valve. Central area extending to both margins forming apically rectangular fascia. Striae parallel, radiate only approaching each apex, and mostly opposite one another across sternum. Stria density 9–12 (often 10) in 10 μm. 10.3897/phytokeys.228.101080.figure61 0AFA99F6-865C-58A4-9963-03D618914BA9 Figure 61. Ulnariafanjingensis sp. nov., ×400, LMA–D living cells in girdle view, note numerous plate-like chromatophores E, F two living cells in valve view, note numerous plate-like chromatophores. Scale bar: 20 μm. https://binary.pensoft.net/fig/867649 10.3897/phytokeys.228.101080.figure62 E7DD9B6D-FEAE-530A-9EA5-FD85C548B007 Figure 62. Ulnariafanjingensis sp. nov., ×400, LMA–N fourteen valves exhibiting a size diminution series, note the lanceolate valve outline and hyaline central area C micrograph of holotype specimen. Scale bar: 20 μm. https://binary.pensoft.net/fig/867650 SEM (Figs 63–66). Frustule rectangular in girdle view (Fig. 63A, see also Fig. 61A–C). Striae continuing onto mantle, absent from centre (Fig. 63B). Epivalve associated with valvocopula and two copulae (Fig. 63B–D, bands labelled B1–B3, B1 = valvocopula); hypovalve associated with valvocopula and one copula (Fig. 63C, D, bands labelled B1–B2, B1 = valvocopula), forming a 3:2 configuration of girdle bands. Valvocopula a closed hoop, same shape as valve outline, closely attached to mantle interior (Fig. 64A), bearing a mostly continuous row of poroids dividing pars interior from pars exterior, located at the midline (Fig. 64B–F), interrupted in the middle (Fig. 64B, two arrows). A row of serrated projections is present on its advalvar edge, each corresponding internally to a virga (Fig. 64C, D, five arrows respectively), lacking ornamentation at both poles (Fig. 64E, F). Each ocellulimbus composed of ca. 12 transverse rows (unequal in length) and ca. 18 pervalvar rows (unequal in length) (Figs 63E, F, 65F). A few serrated apical outgrowths protruding over ocellulimbus, largest two appearing horn-like (Figs 63F, 65E, F, two arrows, respectively). Valve face and mantle intersecting almost at right angle (Fig. 65A–F). Valve characterized by a series of relatively wide virgae, interconnected with thin vimines and closing plates affixed with a few struts to each areolar wall (Fig. 65D–F). Valves with uniseriate striae; each series situated mostly opposite each other, equidistant until radiate at poles (Fig. 66A–F). Central area apically rectangular, extending to both margins (Figs 65B, C, external, 66B, C, internal). One rimoportula located at each pole (Figs 65E, 66E, F). External opening of rimoportula expressed as a simple hole (Fig. 65E); internally bilabiate, situated close to sternum, aligned with striae (Fig. 66E, F). 10.3897/phytokeys.228.101080.figure63 65D97A65-FBDE-50DE-8A84-574390EC56D0 Figure 63. Ulnariafanjingensis sp. nov., girdle view, SEM. A a frustule in girdle view B–D details from A, note the 3:2 configuration of girdle bands E, F apical details from D, showing the closing plates (two arrows respectively) and two horn-like projections (F, two arrowheads). Scale bars: 20 μm (A); 2 μm (B–D); 1 μm (E, F). https://binary.pensoft.net/fig/867651 10.3897/phytokeys.228.101080.figure64 CA560237-829B-5C20-8DEE-A70E5ACABEFA Figure 64. Ulnariafanjingensis sp. nov., internal view, SEM. A a valve with valvocopula B detail from A, note the row of poroids interrupted in the middle (two arrows) C, D details from A. E, F Two apical details from A. Scale bars: 20 μm (A), 4 μm (B–D), 1 μm (E, F). https://binary.pensoft.net/fig/867652 10.3897/phytokeys.228.101080.figure65 D77EE2E0-9B01-5962-8EDD-61620735EEE7 Figure 65. Ulnariafanjingensis sp. nov., external view, SEMA a complete valve B middle detail from A, showing the clear central area C middle detail of another valve showing the central area D a pole from A, note the slightly radiated striae and sub-capitate apex E, F two apices from A, note two largest horn-like projections and ocellulimbus. Scale bars: 20 μm (A); 2 μm (B–D); 1 μm (E, F). https://binary.pensoft.net/fig/867653 10.3897/phytokeys.228.101080.figure66 EEC82F5D-D9F1-58C5-BCA7-E9BFFD46364C Figure 66. Ulnariafanjingensis sp. nov., internal view, SEMA a complete valve B middle part detail from A, note the clear central area C detail of another valve center showing the clear central area D a pole from A, note the tapering valve and rostrate apex E, F two apical details from A, note bilabiate rimoportulae and rostrate apices. Scale bars: 20 μm (A); 5 μm (B–D); 1 μm (E, F). https://binary.pensoft.net/fig/867654 Etymology. Named after Fanjing Mountain, where the species was found. Ecology and distribution. The sampling site is close to the headwaters of Heiwan River, which originates in the Fanjing Mountain National Nature Reserve. The diatom samples were scraped off of the stone surfaces. The following environmental parameters were measured in the field. Electric conductivity was 54.9 ± 1.4 μS∙cm-1, pH was 7.6 ± 0.1, and water temperature was10.4 ± 0.1 °C. Since the diatom sample was scraped off of the surfaces of stones and the conductivity is below 100 μS∙cm-1, U.fanjingensis can be considered an epilithic diatom characteristic of poor electrolyte content fresh water. So far, its distribution is known only from the type locality. Discussion. Ulnariafanjingensis is characterized by its lanceolate valve outline, apically rectangular central area, rostrate to sub-capitate apices, and long valves. It is similar to U.dongtingensis Bing Liu, but they have different valve outlines: U.dongtingensis has narrow-lanceolate valves with parallel central margins the length of the central area whereas U.fanjingensis has parallel central margins extending beyond the central area (see Liu et al. 2019b, p. 134, fig. 14). Taxon classification Plantae Licmophorales Ulnariaceae  Ulnaria hupingensis Bing Liu sp. nov. 1CD231CE-B032-5419-BAB5-8A1D2DBBE385 Figs 67 , 68 , 69 , 70 , 71 , 72 Holotype. Slide JIUDIA202312, specimen circled on slide, illustrated as Fig. 68B. Registration. PhycoBank http://phycobank.org/103818. Type locality. China. Hunan province: Huping Mountain National Nature Reserve, Xie River, a sampling location (30°1'9"N, 110°37'46"E, 400 m a.s.l.), collected by Bing Liu, March 14, 2021. Description. LM (Figs 67, 68). Living cells with numerous discoid chromatophores (Fig. 67A–E, note that these cells may be in an unhealthy condition). Frustule in girdle view rectangular (Figs 67A–C, 68A, see also Fig. 69A). Valves lanceolate with protracted, rostrate to sub-capitate poles (Figs 67D, E, 68B–M, see also Figs 70A, 71A, 72A). Valve dimensions (n = 59): length 81–200 μm, width 5.4–7.0 μm at centre. Sternum distinct, extending length of the valve. Central area completely absent. Striae parallel, radiate only approaching each apex, and mostly opposite one another across sternum. Stria density 9.5–11.5 (often 11) in 10 μm. 10.3897/phytokeys.228.101080.figure67 9055483A-F1C0-5770-B38F-E56311AA41E8 Figure 67. Ulnariahupingensis sp. nov., ×630, LMA–C living cells in girdle view, note numerous irregular chromatophores D, E two living cells in valve view, note numerous discoid chromatophores. Scale bar: 20 μm. https://binary.pensoft.net/fig/867655 10.3897/phytokeys.228.101080.figure68 234FA65F-8EF8-575C-9A3B-9CB0D768EA32 Figure 68. Ulnariahupingensis sp. nov., ×630, LM. A a frustule in girdle view B–M twelve valves exhibiting a size diminution series, note the lanceolate valve outline and completely absent central area B micrograph of holotype specimen. Scale bar: 20 μm. https://binary.pensoft.net/fig/867656 SEM (Figs 69–72). Frustule comprising several girdle bands (Fig. 69A–F). Epivalve associated with valvocopula and two copulae (Fig. 69D, labelled B1 to B3, B1 = Valvocopula); number of copulae associated with hypovalve not verified. Valvocopula a closed hoop, same shape as valve outline, closely attached to mantle interior, surrounding valve margin (Fig. 70A), bearing a mostly continuous row of poroids dividing pars interior from pars exterior, located at midline (Fig. 70B–F), poroids lacking at centre of the valve (Fig. 70B, two arrows). On its advalvar edge, valvocopula bears a row of serrated projections, each corresponding to a virga internally (Fig. 70C, E, three arrows, respectively). Valvocopula lacking ornamentation at both poles (Fig. 70D, F). Valve face and mantle intersecting almost at right angle (Fig. 71A, B). Valve characterized by a series of relatively wide virgae, interconnected with vimines and closing plates affixed with few struts to the areola wall (Fig. 71B). Striae uniseriate (Figs 71B, 72B–E), continuing onto mantle (Fig. 69B–F). Ocellulimbus composed of ca. 19 pervalvar and 11 transverse rows of porelli. Two horn-like projections protruding over the ocellulimbus (Figs 69F, 71C–F, two arrows, respectively). Internally, virgae transversely extending from sternum to mantle, striae situated almost opposite each other across sternum, areolae become more elongated closer to the mantle (Fig. 72B–E). Central area completely lacking (Figs 71A, B, external, 72A, B, internal). One rimoportula usually present at each pole, occasionally two produced at one end (Figs 70D, two arrows, 71D). External opening of rimoportula expresses as a simple hole, forming different shapes (Fig. 71C–F); internally bilabiate, situated close to sternum at an angle (Fig. 72D–F). 10.3897/phytokeys.228.101080.figure69 367B2AC1-29F1-5035-B3CC-D798E18F2952 Figure 69. Ulnariahupingensis sp. nov., girdle view, SEMA a frustule in girdle view B–E details from A, note three copulae (labelled B1 to B3) associated with the epivalve F apical detail from E, showing two horn-like projections (two arrows respectively). Scale bars: 20 μm (A); 2 μm (B–F). https://binary.pensoft.net/fig/867657 10.3897/phytokeys.228.101080.figure70 DC2752B8-02D5-56F7-9719-14F8821385DD Figure 70. Ulnariahupingensis sp. nov., internal view, SEMA a valve with valvocopula B middle detail from A, note the row of poroids interrupted in the middle (two arrows) C, E two poles from A. D Apical detail from C, note two rimoportulae at one apex (two arrows) F apical detail from E, note one rimoportula at one apex. Scale bars: 20 μm (A); 2 μm (B–F). https://binary.pensoft.net/fig/867658 10.3897/phytokeys.228.101080.figure71 F70FA276-16F5-52CA-85BD-EEA5DCDF45CF Figure 71. Ulnariahupingensis sp. nov., external view, SEMA a complete valve B middle part detail from A, note central area complete absent C, D two apical details from A, showing two horn-like projections protruding over the oceullulimbus (two arrows, respectively) E, F two other apical details showing two horn-like projections protruding over the ocellulimbus (two arrows, respectively). Scale bars: 20 μm (A); 1 μm (B–F). https://binary.pensoft.net/fig/867659 10.3897/phytokeys.228.101080.figure72 02030567-1287-5E72-A76C-BE2E951E0CE4 Figure 72. Ulnariahupingensis sp. nov., internal view, SEMA a complete valve B, C middle part details from A, note central area is completely absent D–F apical details from A. Scale bars: 20 μm (A); 2 μm (B–F). https://binary.pensoft.net/fig/867660 Etymology. Named after Huping Mountain National Nature Reserve, where the species was found. Ecology and distribution. Epilithic in a mountain stream with oligotrophic waters. The following environmental parameters were measured in the field: Conductivity was 263 ± 1 μS∙cm-1, pH was 8.4 ± 0.1 and water temperature was 12.4 ± 0.4 °C. So far, its distribution is known only from the type locality. Discussion. Ulnariahupingensis is characterized by its lanceolate valve outline, lacking central area, and rostrate to sub-capitate apices. It differs from U.qinghainensis by its wider valves (5.4–7.0 μm vs 3.1–5.0 μm) and from U.obtusa by its much higher stria density (9.5–11.5 in 10 μm vs 3–4 in 10 μm) (see Williams and Van de Vijver 2021, p. 175). Taxon classification Plantae Licmophorales Ulnariaceae  Ulnaria xieriverensis Bing Liu sp. nov. 72D21C66-FB8F-5BF5-802A-8EE629318A23 Figs 73 , 74 , 75 , 76 Holotype. Slide JIUDIA202313, specimen circled on slide, illustrated as Fig. 73A. Registration. PhycoBank http://phycobank.org/103819. Type locality. China. Hunan province: Huping Mountain National Nature Reserve, Xie River, a sampling location (30°1'9"N, 110°37'46"E, 400 m a.s.l.), collected by Bing Liu, March 14, 2021. Description. LM (Figs 73). Valves generally linear (i.e., valve margins almost parallel), slightly undulate in larger specimens (Fig. 73A–C, see also Fig. 76B, C), parallel in smaller specimens (Fig. 73D–H, see also Figs 74A, 75A, 76A). Valve tapers towards apex, then it is protracted to broadly rostrate poles. Valve dimensions (n = 33): length 64–120 μm, width 6.0–8.6 μm at centre. Sternum distinct, extending length of valve. Central area completely absent. Striae parallel, radiate only approaching each pole, and mostly opposite one another across sternum. Stria density 10.5–12 (often 11) in 10 μm. 10.3897/phytokeys.228.101080.figure73 8D7CF561-604E-5836-86A1-8080BD4F1667 Figure 73. Ulnariaxieriverensis sp. nov., ×1000, LMA–H eight valves exhibiting a size diminution series, note the almost parallel but slightly undulate valve margins in larger specimens (A–C) and parallel valve margins in smaller specimens (D–H). A Micrograph of holotype specimen. Scale bar: 10 μm. https://binary.pensoft.net/fig/867661 SEM (Figs 69–72). Valve characterized by relatively wide virgae, interconnected with vimines, closing plates affixed with a few struts to the areolar wall (Fig. 74B–D). Ocellulimbus composed of ca. 16 pervalvar and 9 transverse rows of porelli. Two horn-like projections protruding over the ocellulimbus (Fig. 74E, F, two arrows, respectively). Striae uniseriate. Stria situated opposite each other across sternum, equidistant until radiate at poles, areolae become elongated closer to the mantle (Fig. 75B–F). One rimoportula present at each pole, externally expressed as a simple hole (Fig. 74C–F), internally bilabiate, situated close to sternum (Fig. 75C, E, F), sometimes displaced, against mantle (Fig. 75D). Central area completely lacking (Figs 74A, B, 75A, B, 76A–D). Valvocopula a closed hoop (Fig. 76A–C). Valvocopula bearing a mostly continuous row of poroids dividing pars interior from pars exterior, located at the midline (Fig. 76D–F), lacking ornamentation at both poles (Fig. 76E, F). On its advalvar edge, valvocopula has a row of serrated projections, each corresponding internally to a virga (Fig. 76D, E, three arrows, respectively). 10.3897/phytokeys.228.101080.figure74 32E50E9D-CB8E-5EED-9E2C-4EF5702C8FCE Figure 74. Ulnariaxieriverensis sp. nov., external view, SEMA a complete valve B middle part detail from A, note central area is completely absent C, D two apical details from A. E, F Two other apical details, note two horn-like projections protruding over the ocellulimbus (two arrows respectively). Scale bars: 10 μm (A); 1 μm (B–F). https://binary.pensoft.net/fig/867662 10.3897/phytokeys.228.101080.figure75 7566FA24-3EF1-5903-BB36-D4AE4A3DC4BE Figure 75. Ulnariaxieriverensis sp. nov., internal view, SEMA a complete valve B middle part detail from A, note central area is completely absent C, D two apical details from A, note one rimoportula located against the mantle (D, arrow) E, F two other apical details. Scale bars: 10 μm (A); 1 μm (B–F). https://binary.pensoft.net/fig/867663 10.3897/phytokeys.228.101080.figure76 3483D8D3-087E-5881-A8BE-8EFE3B6E2986 Figure 76. Ulnariaxieriverensis sp. nov., internal view, SEMA a complete valve with valvocopula B, C two complete valves with valvocopula, note undulate valve margins D middle detail from A, note the central area is completely absent and a row of serrated projections over virgae (three arrows) E, F two apical details from A, note serrated projections over virgae (E, three arrows). Scale bars: 10 μm (A–C); 1 μm (D–F). https://binary.pensoft.net/fig/867664 Etymology. Named after Xie River, where the species was found. Ecology and distribution. Epilithic in a mountain stream with oligotrophic waters. Ulnariahupingensis was found in the same sampling site with U.xieriverensis and the environmental parameters see above. So far, its distribution is known only from the type locality. Discussion. Ulnariaxieriverensis is characterized by its linear valve outline, absence of central area, and rostrate apices. It differs from U.hupingensis by its linear valve outline. Taxon classification Plantae Licmophorales Ulnariaceae  Ulnaria pandurata-uniseriata Bing Liu sp. nov. 729EB5F6-44B1-590D-B42A-51FDD3DFE2BE Figs 77 , 78 , 79 , 80 Holotype. Slide JIUDIA202314, specimen circled on slide, illustrated as Fig. 77C. Registration. PhycoBank http://phycobank.org/103820. Type locality. China. Hunan province: Lanshan County, Shun River, a sampling location (25°11'29"N, 112°7'47"E, 490 m a.s.l.), collected by Bing Liu, October 5, 2021. Description. LM (Figs 77). Valves panduriform with protracted, rostrate apices (Fig. 77A–J, see also Figs 78A, B, 79A, B, 80A, B). Valve dimensions (n = 28): length 70–116 μm, width 6.2–8.2 μm at centre. Sternum distinct, extending length of the valve. Central area distinct, rectangular fascia. Striae parallel, radiate only approaching each apex, and mostly opposite across sternum. Stria density 9–11 in 10 μm. 10.3897/phytokeys.228.101080.figure77 F8EFD244-6EF8-5310-9D95-7F97CB096A4F Figure 77. Ulnariapandurata-uniseriata sp. nov., ×1000, LMA–J ten valves exhibiting a size diminution series, note the panduriform valve outline C micrograph of holotype specimen. Scale bar: 10 μm. https://binary.pensoft.net/fig/867665 10.3897/phytokeys.228.101080.figure78 B95ED0DB-7A14-567B-B79C-A4ECF150F033 Figure 78. Ulnariapandurata-uniseriata sp. nov., external view, SEMA, B two complete valves, note panduriform valve outline C, D two middle part details from A, B, respectively, note rectangular central areas E, F two apical details from B, note two horn-like projections protruding over ocellulimbus. Scale bars: 10 μm (A, B); 1 μm (C, D); 2 μm (E, F). https://binary.pensoft.net/fig/867666 10.3897/phytokeys.228.101080.figure79 95DEEFD8-7173-5005-8FD4-3D043322285D Figure 79. Ulnariapandurata-uniseriata sp. nov., internal view, SEMA, B two complete valves, note panduriform valve outline. C, D middle part details from A, B, respectively, note constricted central parts E, F two apical details from B. Scale bars: 10 μm (A, B); 1 μm (C, D); 2 μm (E, F). https://binary.pensoft.net/fig/867667 SEM (Figs 78–80). Valve characterized by relatively wide virgae, interconnected with vimines (Fig. 78A–D). Ocellulimbus composed of ca. 17 pervalvar and 8 transverse rows of porelli. Two horn-like projections protruding over the ocellulimbus (Fig. 78E, F). Striae uniseriate, situated opposite each other across sternum, equidistant until radiate at poles, areolae become elongated closer to the mantle (Figs 78C, D, 79C, D). One rimoportula present at each pole, externally expressed as a simple hole (Fig. 78E, F), internally bilabiate, situated close to sternum (Figs 79E, F, 80E, F). Central area rectangular hyaline region (Figs 78C, D, 79C, D). Valvocopula a closed hoop, surrounding the valve internal margin (Fig. 80A, B), bearing a mostly continuous row of poroids dividing pars interior from pars exterior, located at the midline (Fig. 80B, D–F), lacking ornamentation at both poles (Fig. 80E, F). On its advalvar edge, valvocopula has a row of serrated projections, each corresponding internally to a virga (Fig. 80B, D–F). 10.3897/phytokeys.228.101080.figure80 8B8F01AD-C57B-5E25-88A9-F72251D8BEF3 Figure 80. Ulnariapandurata-uniseriata sp. nov., internal view, SEMA, B two complete valves with valvocopula C, D two middle details from A, B, respectively E, F two apical details from B. Scale bars: 10 μm (A, B); 2 μm (C–F). https://binary.pensoft.net/fig/867668 Etymology. The epithet pandurata>-uniseriata is a combination of the terms pandurate and uniseriate reflecting the panduriform outline of the valve and its mostly uniseriate striae. Ecology and distribution. Epilithic in a mountain stream with oligotrophic waters. The following environmental parameters were measured in the field: Conductivity was 53.9 ± 0.6 μS∙cm-1, pH was 8.4 ± 0.3 and water temperature was 21.9 ± 0.1 °C. So far, its distribution is known only from the type locality. Discussion. Ulnariapandurata-uniseriata is characterized by its panduriform valve outline, rectangular central area, mostly uniseriate striae, and its rostrate apices. It differs from U.jumlensis (Jüttner) D.M. Williams & Karthick by its narrower valve (6.2–8.2 μm vs 7.5–11.2 μm) and lower stria density (9–11 in 10 μm vs 13–14 in 10 μm) (see Jüttner et al. 2000, p. 249). Ultrastructure and configuration of girdle bands Valvocopula ultrastructure: In the above “Taxonomic treatment”, we illustrate a whole valvocopula that is separate from the valve in U.neobiceps sp. nov. (Fig. 53), which is a species possessing uniseriate striae. Here, we add an observation of a whole valvocopula from U.ulnabiseriata (Fig. 81), which is a species possessing mostly biseriate striae. Based on our observations all Ulnaria valvocopulae have similar ultrastructure: 1) the valvocopula is a closed hoop (Figs 53A, 81A); 2) usually, a row of poroids, which are interrupted in the middle (Figs 53B, 81B) and at two apices (Figs 53C–F, 81E, F), located at the midline, dividing pars interior from pars exterior; 3) the poroids of valvocopula are occluded by the closing plates same as those on valve surface (see Figs 43C, 47D, F); 4) on its advalvar edge (i.e., the edge of pars interior) except at its apical ends, valvocopula produces a row of serrated projections (which the other copulae do not produce) aligned with each virga (Fig. 81C–F); 5) at its apical end of the valvocopula, the advalvar edge forms a shelf which projects into the cell interior underneath the ocellulimbus (Figs 38F, 53C–F). 10.3897/phytokeys.228.101080.figure81 2F42A2BF-6F42-5CA4-80D9-1D68E52EC7FF Figure 81. Valvocopula of Ulnariaulnabiseriata, SEM. Scale bar: 20 μm (A); 5 μm (B–F). https://binary.pensoft.net/fig/867669 Configuration of girdle bands: The number of girdle bands associated with the hypovalve may vary, as can the number of girdle bands associated with the epivalve in the same species. Evidence is found in U.oxybiseriata D.M. Williams & Bing Liu and U.jishou-biseriata sp. nov. as the number of girdle bands associated with the epivalve can be either 3 (see Liu et al. 2019b, fig. 3C, E, F) or 4 (Fig. 82C, D, labelled B1 to B4) in U.oxybiseriata and U.jishou-biseriata (see Figs 21, 22). Thus, we interpret the configuration of girdle bands will change during the cell cycle. Some specific details are provided below and summarized in Table 5. Table 5. Ultrastructure and configurations of girdle bands in 11 Ulnaria species. Species Mantle depth (μm) Poroids in girdle bands Configuration of girdle bands (dividing cells) Configuration of girdle bands (non-dividing cells) U.constricta-biseriata sp. nov. 2–4 Two rows of poroids produced in both 2nd and 3rd band, but the 2nd row of poroids discontinuous 3:3 3:2 U.dongtingensis 2–3 One row of poroids in all girdle bands No data (one ratio should be 3:3) 3:2 U.fanjingensis sp. nov. 2–3 One row of poroids in girdle bands except third copula which has second interrupted row of poroids No data (one ratio should be 3:3) 3:2 U.gaowangjiensis 3–4 Second interrupted row of poroids in 4th copula 4:4 No data U.hupingensis sp. nov. 2–3.5 Second interrupted row of poroids in 2nd copula No data Three girdle bands associated with the epivalve U.jinbianensis sp. nov. 2–3 One row of poroids in all girdle bands No data (one ratio should be 4:4) 4:2 at beginning U.jishou-biseriata sp. nov. 2–3 Second interrupted row of poroids in 3rd copula No data 3:3 or 4:3 U.oxybiseriata 2–3 Second interrupted row of poroids in 3rd copula 3:3 4:3 U.sinensis 2–4 One row of poroids in all girdle bands No data (one ratio should be 4:4) 4:2 U.sangzhi-biseriata sp. nov. 2–3 Second interrupted row of poroids in 3rd and 4th copulae No data (one ratio should be 4:4) 4:2 U.ulnabiseriata 2–3 One row of poroids in all girdle bands 4:4 4:2 In Ulnariaconstricta-biseriata sp. nov., the epivalve is associated with a valvocopula and two copulae, so it has an overall configuration of 3:3 in dividing cells or 3:2 in non-dividing cells (Fig. 15). Two rows of poroids are present on both the second and third band; the second row of poroids is discontinuous (Fig. 15B–E). In the original description of U.dongtingensis (Liu et al. 2019b, p. 127), the girdle band configuration was not recorded. Further investigation revealed a 3:2 configuration of girdle bands in non-dividing cells (Fig. 83). In U.fanjingensis sp. nov., it has a 3:2 configuration in non-dividing cells (see Fig. 63B–D). In U.gaowangjiensis Bing Liu & D.M. Williams, its original description (Liu et al. 2017, p. 253) stated a 3:3 configuration in dividing cells but this is incorrect because further investigation revealed a 4:4 configuration in dividing cells (Fig. 84). In U.hupingensis sp. nov., three girdle bands are associated with the epivalve (see Fig. 69D). In U.jishou-biseriata sp. nov., it has a 3:3 or 4:3 configuration in dividing cells (see Figs 21, 22). In U.oxybiseriata, there is a 3:3 configuration in dividing cells (see Liu et al. 2019b, fig. 3C, E, F), but some non-dividing cells have a 4:3 configuration (Fig. 82). Ulnariajinbianensis S. Blanco & Bing Liu (Fig. 85), U.sangzhi-biseriata sp. nov. (Fig. 31), and U.sinensis Bing Liu et D.M. Williams (see Liu et al. 2017, figs 11–13), all have a 4:2 configuration of girdle bands in non-dividing cells. Ulnariaulnabiseriata has a 4:4 configuration in dividing cells (see Liu et al. 2017, figs 37–40). 10.3897/phytokeys.228.101080.figure82 EA2E18E7-D0EF-5853-9644-83E78A6D3F39 Figure 82. Configuration of girdle bands in Ulnariaoxybiseriata, SEMA–D four bands associated with the epivalve. Scale bars: 10 μm (A); 2 μm (B–D). https://binary.pensoft.net/fig/867670 10.3897/phytokeys.228.101080.figure83 E294542E-12B3-5BC6-A43C-12E29291ABAD Figure 83. Configuration of girdle bands in Ulnariadongtingensis, SEMA, B a 3:2 configuration of girdle bands in non-dividing cells. Scale bars: 10 μm (A); 2 μm (B). https://binary.pensoft.net/fig/867671 10.3897/phytokeys.228.101080.figure84 20F3C63B-D7F7-5591-BEFE-A467CFB1DD2E Figure 84. Configuration of girdle bands in Ulnariagaowangjiensis, SEMA–C four bands associated with the epivalve D A 4:4 configuration of girdle bands in dividing cells. Scale bars: 20 μm (A); 2 μm (B–D). https://binary.pensoft.net/fig/867672 10.3897/phytokeys.228.101080.figure85 EB179608-68E5-5749-B6C1-5A5035A56528 Figure 85. Configuration of girdle bands in Ulnariajinbianensis, SEMA–D a 4:2 configuration of girdle bands in non-dividing cells. Scale bars: 10 μm (A); 5 μm (B–D). https://binary.pensoft.net/fig/867673 Based on our published data (Liu et al. 2017, 2019a, b) and the above observations, the following conclusions can be drawn: 1) the valvocopula is different from the other copulae in ultrastructure; 2) the number of girdle bands associated with the epivalve is usually 3 or 4, but it varies among different Ulnaria species and even within the same species; 3) the configuration of girdle bands in dividing cells is either 4:4 or 3:3, i.e., the epivalve and hypovalve have the same number of girdle bands; 4) the deep mantle (often more than 2 μm) plus all girdle bands of a cell causes the cell depth to usually larger than the valve width so that the Ulnaria cells usually lie in girdle view on a slide. Discussion The life history of Ulnaria There are rarely reports of the whole life history in the araphid diatoms, but a few papers mention the transverse perizonal bands of the initial cell. For example, Williams noted “no sign of transverse perizonal bands at all” in Fragilariformavirescens (Ralfs) D.M. Williams & Round (Williams 2001). Williams & Metzeltin noted that the auxospore/initial cells were rather large (more than 250 μm), curved along their length, with an irregular basal siliceous layer and the valve outline sometimes interrupted by undulations or a central inflation in a species of Ulnaria (Williams and Metzeltin 2004). Liu and Williams (2020) revealed the life history (except auxospore) of Hannaeainaequidentata (Lagerstedt) Genkal & Kharitonov and proposed that the life history of H.inaequidentata can be divided into the following four series of successive stages: auxospore, initial cell, pre-normal vegetative cell, and normal vegetative cell. There is a distinct pre-normal stage (i.e., from the initial cell finally to the normal cell) during which the life history must go through at least several generations (Liu and Williams 2020). Mann and Chepurnov observed the postauxospore shape modification of Neidiumampliatum (Ehrenberg) Krammer and found that its rostrate poles develop very quickly during the first divisions of the initial cell (Mann and Chepurnov 2005, p. 339) so that its pre-normal stage is very short. In Ulnaria, we found that U.ulnabiseriata has the same life history as H.inaequidentata. Although more investigations will be carried out in the future, a distinct pre-normal vegetative cell stage existing in both Hannaea and Ulnaria can be determined. The lack of transverse perizonium bands may be the cause of the chaos process – from irregular initial cells to irregular pre-normal vegetative cells – during its developing period from the initial cell to the normal vegetative cell (Liu and Williams 2020, p. 81). Living cells of Ulnaria We observed living cells of five Ulnaria species (U.fanjingensis sp. nov., Fig. 61; U.hupingensis sp. nov., Fig. 67; U.jishou-biseriata sp. nov., Fig. 19; U.oxybiseriata Fig. 86; U.sinensis, Fig. 87). Only U.sinensis forms ribbon-like colonies (Fig. 87 showing a colony of U.sinensis composed of more than 40 cells joined face-to-face) whereas in the other four Ulnaria species are solitary. Round et al. (1990) pointed out that in Synedra (=Ulnaria) “Plastids: usually two long plates lying against the girdle and overlapping slightly on to the valve face. These may split up in unhealthy material, giving the impression of numerous discoid chromatophores”. Few authors discuss observations on the plastids of Ulnaria cells since Round et al. (1990). Morales et al. (2014) discussed living colonies of two Ulnaria species but did not mention their plastids. We observed that U.jishou-biseriata has two long valve-appressed chloroplasts per cell (Fig. 19). This agrees with the observation of Round et al. (1990). We also found that numerous discoid chromatophores are present in U.fanjingensis (Fig. 61), U.hupingensis (Fig. 67), U.oxybiseriata (Fig. 86), and U.sinensis (Fig. 87). The samples including these species were collected from the localities far away from our laboratory and their living cells were photographed after at least 24 hours of being collected, so their plastids may have changed from a long plate to numerous discs as the cells became unhealthy. 10.3897/phytokeys.228.101080.figure86 C7D8DDC4-3790-5EBD-99BA-4060666EC04A Figure 86. Ulnariaoxybiseriata, ×630, LMA, B living cells in girdle view, note numerous irregular chromatophores C–F four living cells in valve view, note numerous discoid chromatophores. Scale bar: 20 μm. https://binary.pensoft.net/fig/867674 10.3897/phytokeys.228.101080.figure87 BBACA7E2-DD22-58F7-8E42-3B2D347883B6 Figure 87. Ulnariasinensis, ×200, LM. A colony formed by more than 40 cells joined face-to-face, note numerous discoid chromatophores. Scale bar: 100 μm. https://binary.pensoft.net/fig/867675 Basal siliceous layer Ross et al. defined the basal siliceous layer as “the layer that forms the basic structure of the various components of the frustule” (Ross et al. 1979, p. 525). In Ulnaria, its basal siliceous layer composed of sternum, virgae, vimines/viminules, and striae. Researchers around the world have described many new Ulnaria species by using these terms (see Appendices 1–3 and references therein). However, some incompletely silicified valves can provide a good understanding of its basal siliceous layer even though I have illustrated and labelled most terms (see Figs 1, 2). Figure 88 shows the basal siliceous layer of U.jishou-biseriata sp. nov. This incompletely silicified valve is composed of sternum and virgae but the viminules were not developed, though the central area is already formed (Fig. 88). Figure 89 shows the basal siliceous layer of U.fanjingensis sp. nov. This incompletely silicified valve is composed of sternum, virgae, and vimines, and the central area formed and with ghost striae (Fig. 89). Figure 90 shows the basal siliceous layer of U.gaowangjiensis. This incompletely silicified valve is composed of sternum, virgae, and viminules, and the central area formed but the closing plates did not (Fig. 90). During the raphid diatom ontogeny, Round et al. (1990) revealed that the pattern of silica deposition as the raphid valve forms is that the primary side of the sternum forms first, then the secondary side of the sternum forms, and finally the formation of the valve. The ontogeny of Ulnaria is not well known. Based on our observations (Figs 88–90), the pattern of silica deposition in the valve formation is likely that the sternum forms first, next the virgae form, finally the formation of the valve. 10.3897/phytokeys.228.101080.figure88 587F2760-F26F-53F9-A864-666F782AF2FB Figure 88. Ulnariajishou-biseriata sp. nov., internal view, SEMA–F an incompletely silicified valve showing valve basic structure composed of sternum and virgae. Scale bar: 20 μm (A); 4 μm (B–F). https://binary.pensoft.net/fig/867676 10.3897/phytokeys.228.101080.figure89 6AA34B6B-7177-5789-8CA3-7CE6F58CD2F0 Figure 89. Ulnariafanjingensis sp. nov., external view, SEMA–D an incompletely silicified valve showing basic structure composed of sternum, vimines, and virgae, note some ghost striae in the central area. Scale bars: 20 μm (A); 2 μm (B–D). https://binary.pensoft.net/fig/867677 10.3897/phytokeys.228.101080.figure90 60601A41-8BE4-5F76-BE7D-0227F576C152 Figure 90. Ulnariagaowangjiensis, external view, SEMA–D an incompletely silicified valve showing basic structure composed of sternum, viminules, and virgae. Scale bars: 10 μm (A); 3 μm (B–D). https://binary.pensoft.net/fig/867678 The striae are usually divided into three types: uniseriate, biseriate and multiseriate striae (Ross et al. 1979, Round et al. 1990). However, the situation is more complicated in Ulnaria because “mixed stria” may exist in some Ulnaria species. Following its definition (see above morphological terminology section), the mixed striae can be divided into three types at least. Figure 91 illustrates and labels these three types of mixed stria. The first type of mixed stria is one which is mostly uniseriate with small sections being biseriate, and an example of which is seen in U.jinbianensis (Fig. 91A, B). The second type of mixed stria is one which is the reverse being mostly biseriate with a small section (usually 1 to 2 areolae near sternum) of uniseriate. This type of mixed stria is the most common striae in “biseriate stria Ulnaria” (e.g., in U.constricta-biseriata, U.jishou-biseriata). The third type of mixed stria is one which is composed of a biseriate, a triseriate, and a small uniseriate (usually 1 to 2 areolae near sternum) sections, and example of which is seen in U.pandurata-biseriata (Fig. 91C, D). Thus, in fact, there are not whole biseriate striae in Ulnaria because the biseriate striae often become uniseriate – a very short part composed of usually 1 to 2 areolae – near sternum (e.g., in U.constricta-biseriata, U.jishou-biseriata). However, the uniseriate striae can be complete throughout the whole valve (e.g., in U.menyuanensis, U.neobiceps, U.chengduoensis, U.qinghainensis, U.fanjingensis, U.hupingensis, and U.xieriverensis). Additionally, in the distribution of striae on the valve from pole to pole, in the “biseriate stria Ulnaria species”, a few complete uniseriate striae maybe occur near each apex (see Figs 17, 24, 27, 33, 36). To date, no Ulnaria species have been found to possess mostly triseriate or quadraseriate striae. But a few quadraseriate striae are found in the mantle of U.gaowangjiensis (Fig. 92). The origin of the term viminule is obscure and although attributed to Cox (2012), it does not appear in that paper or any others but was used comprehensively by Morales et al. (2019). For the uniseriate striae there are only virgae and vimines but for the biseriate striae or multiseriate striae there are tiny ribs interconnecting each other to define the areolae. To distinguish the vimines in the uniseriate striae from the tiny ribs in the bi- or multiseriate striae, we formally define the viminules which have been used but not defined in Morales et al. (2019), Morales (2021), and Wetzel and Ector (2021). 10.3897/phytokeys.228.101080.figure91 97163EA6-CFC1-56AB-BFC4-D3F038E49003 Figure 91. Mixed striae of Ulnaria, SEMA, B mixed striae in U.jinbianensisC, D mixed striae in U.pandurata-biseriata sp. nov. Scale bars: 2 μm (A–D). https://binary.pensoft.net/fig/867679 10.3897/phytokeys.228.101080.figure92 072D5F97-9D20-5BA9-9A64-77599821A6FD Figure 92. Mixed striae and poroids of girdle bands in Ulnariagaowangjiensis, SEMA a frustule B–D mixed striae in mantle (arrows), isolated poroids in second band (B2, arrowheads), and two rows of poroids in third band (B3, wavy arrows). Scale bars: 10 μm (A); 2 μm (B–D). https://binary.pensoft.net/fig/867680 Closing plates occlude the external openings of areolae in Ulnaria (sensu Williams 1986). The structure of the closing plates in both uniseriate and mostly biseriate striae is similar, though the closing plates are different in size (Fig. 93). The closing plates are a plate that does not completely occlude the outside opening of areola. This plate is usually solid (sometimes with 1–3 perforations) and has a few struts affixed to each areolar wall. The mature closing plates lie flush with the valve surface. The closing plates in the uniseriate and mostly biseriate striae are illustrated and compared in Figure 93. The areola (pore) occlusions were defined in Ross and Sims (1972), Ross et al. (1979) and Mann (1981). Cox (2004) reassesses their structure and terminology and concludes the closing plate in Ulnaria cannot be attributed to a cribrum, hymen, rica, or rota, but it may be considered as a vola which is a catch-all term. To be precise, we use closing plate rather than vola. 10.3897/phytokeys.228.101080.figure93 B3BCF1BE-C514-55CA-BBB2-26E69BD9FEC0 Figure 93. Closing plates of Ulnaria, external view, SEMAU.wulingensisBU.fanjingensis sp. nov. CU.oxybiseriataDU.jishou-biseriata sp. nov. Scale bars: 300 nm (A, B, D); 600 nm (C). https://binary.pensoft.net/fig/867681 Central area, Ocellulimbus and Rimoportula Ross et al. (1979) defined the central area as “an expanded or otherwise distinct portion of the axial area midway along its length”. The essence of this definition is that the central area is a hyaline area of no ornamentation. The central area is variable in Ulnaria taxa. Some species have a distinct central area (e.g., U.gaowangjiensis and U.ulnabiseriata, Fig. 94,), some have a very variable central area (e.g., U.blancoi and U.neobiceps), and some have distinctive ghost striae in the central area (e.g., U.menyuanensis, Figs 44, 94E, F). The ghost striae are formed by the unperforated grooves in the valve interior of the central area (sensu Lange-Bertalot and Ulrich 2014). Ulnariamenyuanensis has distinctive ghost striae in the central area just because in its valve central area there are remarkable internal unperforated grooves present (see Fig. 94E, F). Interestingly, ghost striae appear in the incompletely silicified valve of U.fanjingensis sp. nov. (Fig. 89) but do not appear in the mature valves (Fig. 62) because the internal grooves are fully silicified in the mature valves (see Fig. 66B, C). Most species described in this study have ghost striae in their central areas (except these species lacking a central area) because there are different levels of shallow grooves present. If the grooves are very shallow or not present, then no ghost striae are observed under LM. 10.3897/phytokeys.228.101080.figure94 DAC8F454-8211-5FB3-9197-AB2EE877BB1F Figure 94. Central areas and ghost striae in Ulnaria, SEMA, BU.gaowangjiensisC, DU.ulnabiseriataE, FU.menyuanensis sp. nov. Scale bars: 3 μm (A–F). https://binary.pensoft.net/fig/867682 At first, the ocellulimbus was defined as a special type of pore field, a “plate set into the polar valve mantle” (Williams 1986, p. 146). In Ulnaria, ocellulimbus is composed of some pervalvar and transverse rows of porelli. Both pervalvar and transverse rows are unequal in length. The porelli are not occluded. The apical end of the valvocopula forms a shelf which projects into the cell interior underneath the ocellulimbus and it may block some porelli (see Figs 23D, E, 29C, D, 43E, F). In the normal vegetative cells, the inset ocellulimbus has pervalvar rows of porelli which are vertical (Fig. 95) whereas in the initial cell the ocellulibus extends onto the valve surface (Fig. 5F). 10.3897/phytokeys.228.101080.figure95 88AAE0F5-E3F9-5EF2-9246-ABF60640D39B Figure 95. Ocellulimbus and rimoportula in Ulnaria, SEMA–CU.fanjingensis sp. nov. (A, B external views C internal view) D–FU.jishou-biseriata sp. nov. (D external view E, F internal views). Scale bars: 300 nm (A–F). https://binary.pensoft.net/fig/867683 The rimoportulae in all Ulnaria have the same structure (more or less) – they are simple holes externally and bilabiate internally – with the number present and some aspects of the shape and position varying. One rimoportula is present at each apex in most Ulnaria species. However, in three Ulnaria species, U.colcae Van de Vijver & Cocquyt, U.macilenta E. Morales, C.E. Wetzel & S.F. Rivera, and U.titicacaensis E. Morales, Ector & P.B. Hamilton, only one rimoportula is present at one apex per valve (Van de Vijver and Cocquyt 2009, Morales et al. 2014). Interestingly, some Ulnaria species which usually have two rimoportulae (one at each apex) per valve, can also have three rimoportulae per valve (one at an apex and two at the other apex). Examples are in U.pandurata-biseriata sp. nov. (Fig. 96A, two rimoportulae per valve; Figs 96B, 97D, two rimoportulae at one apex, thus three rimoportulae per valve), U.hupingensis sp. nov. (Fig. 97A, two rimoportulae at one apex), U.oxybiseriata (Fig. 97B, two rimoportulae at one apex), and U.jishou-biseriata sp. nov. (Fig. 97C, two rimoportulae at one apex). 10.3897/phytokeys.228.101080.figure96 37156948-6550-56FB-9FD9-82EB9A23391A Figure 96. Rimoportulae in Ulnariapandurata-biseriata sp. nov., internal view, SEM. Scale bars: 6 μm (A, B). https://binary.pensoft.net/fig/867684 10.3897/phytokeys.228.101080.figure97 18210B7D-3AFF-549A-B77E-1DA0AD33C233 Figure 97. Rimoportulae in Ulnaria, internal view, SEMAU.hupingensis sp. nov. BU.oxybiseriataCU.jishou-biseriata sp. nov DU.pandurata-biseriata sp. nov. Scale bars: 1 μm (A–D). https://binary.pensoft.net/fig/867685 Valvocopula ultrastructure and the configuration of girdle bands In the 14 Ulnaria taxa described in this study, only in U.chengduoensis sp. nov. was the valvocopula not observed. We also document the whole valvocopula that is separate from the valve in U.neobiceps sp. nov. (Fig. 53) and U.ulnabiseriata (Fig. 81). Williams (2020, p. 5, figs 15–17) illustrated the valvocopula of Ulnariavitrea (Kützing) E. Reichardt. Later, Williams and Van de Vijver (2021, p. 173, figs 40–43) illustrated the valvocopula of U.aequalis (Kütz.) D.M. Williams et Van de Vijver. The valvocopula of the Ulnaria we describe here has a similar ultrastructure to those previously published. In a diatom cell, the configuration of girdle bands is defined as the ratio between the number of girdle bands associated with the epivalve and those associated with the hypovalve (sensu Mann 1982). We may be the first to use this term in Ulnaria. Mann (1982, p. 173) pointed out that “There is a determinate number of bands in the mature cingulum, which again appears to be common condition in raphid diatoms”. The configuration of girdle bands can also be a common condition in araphid diatoms based our investigations. Other examples are Ctenophorasinensis Bing Liu & D.M. Williams, Hannaeainaequidentata, and Diatomasinensis Bing Liu & Rioual. There is a 4:2 configuration of girdle bands in the normal vegetative cells of both C.sinensis (Liu et al. 2020) and D.sinensis (Yuan et al. 2022). There is a 4:2 configuration of girdle bands in the normal but not dividing vegetative cells of H.inaequidentata whereas a 4:4 configuration appears in the dividing vegetative cells (Liu and Williams 2020). In 11 of the Ulnaria species investigated by us (Table 5), the number of girdle bands associated with the epivalve are either three or four and there are at least two girdle bands associated with the hypovalve. Thus, each cell has at least five girdle bands. The mantle depth is more than 2 μm (Table 5). Thus, the Ulnaria cell depth, which includes the depth of two mantle plus the depth of at least five overlapped girdle bands, is often larger than the width of the valve so that the Ulnaria cells often lie in girdle view on a slide. Published reports of the configuration of girdle bands in Ulnaria are rare. Only Zakharova et al. (2020, p. 42, fig. 3) stated, “tree (sic., should be three) closed girdle bands of each valve are pointed by arrowheads” which means there is a 3:3 configuration of girdle bands in U.pilum Kulikovskiy & Lange-Bertalot. The different methods of processing the diatom samples may be one of the reasons. The usual practice causes the diatom frustule to usually separate into two valves rather than to keep the frustule intact. Acquiring the specimens with intact frustules is the key to demonstrate the configuration of girdle bands. Based on our experience, if the diatom samples are heated gently for a shorter time, the intact frustules with all girdle bands can be easily found. Summary and future work The life history of Ulnaria was revealed in this study for the first time. A distinct pre-normal vegetative cell stage exists during the process from the initial cells to the normal vegetative cells. The configuration of girdle bands of 11 species and the valvocopula ultrastructure of 13 species are observed, illustrated, and described. A conclusion can be drawn at this moment that the configuration of girdle bands in Ulnaria cells is a common condition based on this study and our previous studies. The configuration of girdle bands changes during the cell cycle and the number of girdle bands in a cell will reach its maximum at the late stage of cell dividing. Thus, to prove all the girdle bands are closed, you must observe the cell at the late stage of cell division, which is difficult to achieve in practice. Herein, I recommend the closed valvocopula as a defining character for the genus Ulnaria because it is more feasible in practice and an equally effective alternative to “closed girdle bands”. Most Ulnaria species possess uniseriate striae. Three types of mixed striae in Ulnaria are observed in this study. If we hypothesize that the first type of mixed striae is a transitional type from the uniseriate striae to mostly biseriate (the second type of mixed striae), and the third type of mixed striae is a transitional type from the mostly biseriate to the mostly triseriate striae, then we predict that the existence of Ulnaria species, which possesses mostly triseriate striae, is waiting to be found in nature. Supplementary Material XML Treatment for Ulnaria constricta-biseriata XML Treatment for Ulnaria jishou-biseriata XML Treatment for Ulnaria pandurata-biseriata XML Treatment for Ulnaria sangzhi-biseriata XML Treatment for Ulnaria wuling-biseriata XML Treatment for Ulnaria blancoi XML Treatment for Ulnaria menyuanensis XML Treatment for Ulnaria neobiceps XML Treatment for Ulnaria chengduoensis XML Treatment for Ulnaria qinghainensis XML Treatment for Ulnaria fanjingensis XML Treatment for Ulnaria hupingensis XML Treatment for Ulnaria xieriverensis XML Treatment for Ulnaria pandurata-uniseriata Acknowledgements I thank three master’s degree candidates, Wen-Hui Mo, Ji-Yan Long and Li Yuan, for their assistance in the field and the laboratory. I am also very grateful to two reviewers and the editors for their careful revisions and helpful comments. Additional information Conflict of interest The author has declared that no competing interests exist. Ethical statement No ethical statement was reported. Funding This work was supported by the National Natural Science Foundation of China (No. 31760051) and the Natural Science Foundation of Hunan Province [No. 2018JJ2311]. Author contributions Writing – review and editing: BL. Author ORCIDs Bing Liu https://orcid.org/0000-0002-8516-325X Data availability All of the data that support the findings of this study are available in the main text or Supplementary Information. Appendix 1 Table A1. Seven Ulnaria taxa possessing both uniseriate striae and marginal spines. No. Taxon Valve outline Valve dimensions (μm): length (L), width (W) Central area Striae density (in 10 μm) Nature of girdle bands References 1 U.cochabambina Linear-lanceolate with subrostrate or sub-capitate apices L: 88–296; W: 8–9 Square or rectangle fascia 8–10 Valvocopula closed Morales et al. 2009, Williams 2011 2 U.fragilariaeformis Linear-lanceolate with rostrate or sub-capitate apices L: 105–120; W: 3–5 Absent No data Closed Williams 2020 3 U.monodii Linear with with sub-capitate apices L: 140–400; W: 7.5–8.5 Absent 8–9 Closed Cantonati et al. 2018 4 U.pseudogaillonii Linear with attenuate and rounded apices L: 220–410; W: 8–10 Absent 7–9 Unknown Kobayasi and Idei 1979, Kobayasi et al. 2006 5 U.sinensis Linear with rostrate apices L: 296–512; W: 6–8 Absent 8–9 Closed Liu et al. 2017 6 U.undulata Linear with rostrate to sub-capitate apices No data Absent No data Closed Williams 2020 7 U.ungeriana Linear-lanceolate with cuneately rostrate apices L: 85–230; W: 8–10 Very variable (7) 8–10 Unknown Williams 1986, Compère 2001 Appendix 2 Table A2. Fourteen Ulnaria taxa possessing biseriate striae. No. Taxon Valve outline Valve dimensions (μm): length (L), width (W) Central area Striae density (in 10 μm) Nature of girdle bands References 1 U.acuscypriacus Linear-lanceolate with sub-capitate apices L: 140–300; W: 6–6.8 Rectangular or square as incomplete fascia 8.5–10 At least two copulae closed Cantonati et al. 2018 2 U.constricta-biseriata sp. nov. Linear-lanceolate, constricted at centre, with rostrate to sub-capitate apices L: 66–166; W: 5.5–8 Rectangular or square fascia 10–12 Closed This paper 3 U.gaowangjiensis Linear with rostrate apices L: 61–108; W: 6.5–8.5 Square fascia 9–11 Closed Liu et al. 2017 4 U.goulardii Lanceolate with a distinctive constriction at the centre, apex cuneately rostrate L: 55–90; W: 8–10 Rectangular or square fascia 9–11 Unknown Williams 1986, Wetzel et al. 2022 5 U.gusliakovii Linear with rostrate apices L: 110–256; W: 4.5–6 Absent 10 Closed Genkal et al. 2022 6 U.jishou-biseriata sp. nov. Lanceolate with rostrate apices L: 139–200; W: 6–8 Variable 10–12 Closed This paper 7 U.lanceolata Linear with cuneately rostrate apices L: 55–75; W: 8–10 Rectangular or square fascia 8–10 Unknown Williams 1986, Compère 2001 8 U.nyansae Linear with sub-capitate to capitate apices L: 55–175; W: 8–15 Half fascia (12) 13–15 Unknown Williams 1986, 2011 9 U.oxybiseriata Linear-lanceolate to lanceolate with apiculate apices L: 56–78; W: 6–9 Rectangular or trapezoid fascia 10–12 Valvocopula closed Liu et al. 2019a 10 U.pandurata-biseriata Panduriform with rostrate apices L: 37–60; W: 7–9.5 Variable 9–11 Valvocopula closed This paper 11 U.sangzhi-biseriata sp. nov. Linear-lanceolate with capitate to sub-capitate apices L: 49–91; W: 6.5–8.2 Rectangular or square fascia 10–12 Closed This paper 12 U.ulnabiseriata Linear-lanceolate with rostrate to sub-capitate apices L: 105–229; W: 6–8 Rectangular fascia 9–11 Closed Liu et al. 2017 13 U.ulnavar.spathulifera Linear with spatulate apices L: 134–190; W: 8–9 Circular to rectangular, sometimes flanked by short striae 9–10 Unknown Morales et al. 2007, Aboal et al. 2003 14 U.wuling-biseriata sp. nov. Linear with rostrate to sub-capitate apices L: 160–200; W: 6.5–8 Rectangular or trapezoid fascia 10–11 Valvocopula closed This paper Appendix 3 Table A3. Forty-two Ulnaria taxa possessing uniseriate striae but no marginal spines. No. Taxon Valve outline Valve dimensions (μm): length (L), width (W) Central area Striae density (in 10 μm) Nature of girdle bands References 1 U.acus Lanceolate L: 90–100; W: 4–6 Variable 12–15 Closed Williams and Blanco 2019 2 U.aequalis Linear L: 50–200; W: 5–10 Variable 4–6 Closed Williams and Van de Vijver 2021 3 U.amphirhynchus Linear with rostrate apices No data No data No data Unknown Ehrenberg 1843, Bukhtiyarova and Compère 2006 4 U.biceps Lanceolate with capitate apices No data No data No data Unknown Kützing 1844, Compère 2001 5 U.blancoi sp. nov. Lanceolate with rostrate to sub-capitate apices L: 104–236: W: 4.6–6.8 Very variable 10–13 Valvocopula closed This paper 6 U.capitata Linear with capitate, rhomboid apices L: 255–406; W: 8 No clear central area 10–11 Unknown Morales et al. 2007, Compère 2001 7 U.chengduoensis sp. nov. Linear with rostrate apices L: 42–66; W: 6–8 Not clearly visible due to presence of ghost striae or absent 12–15 Unknown This paper 8 U.colcae Linear to linear-lanceolate with subrostrate apices L: 18–46; W: 3.9–5.2 Asymmetrical, rectangular to circular fascia 16–17 Closed Van de Vijver and Cocquyt 2009 9 U.contracta Constricted valve outline with rostrate to subrostrate apices L: 84–140; W: 5–6 Rectangular of variable length 11–14 Unknown Morales et al. 2007, Morales and Vis 2007 10 U.danica Lanceolate with rostrate to sub-capitate apices No data No data No data Unknown Kützing 1844, Bukhtiyarova and Compère 2006 11 U.delicatissima Needle-shaped with sub-capitate apices L: 142–330; W: 4.2–5 Variable 8.5–10 Unknown Lange-Bertalot and Ulrich 2014 12 U.dongtingensis Narrow-lanceolate with rostrate to capitate apices L: 106–260; W: 5–7 Square fascia 10–12 Closed Liu et al. 2019b 13 U.fanjingensis sp. nov. Lanceolate with rostrate to sub-capitate apices L: 165–291; W: 4.8–6.3 Apically rectangular fascia 9–12 Closed This paper 14 U.ferefusiformis Linear-lanceolate with sub-capitate apices 76–152, 4–4.8 L: 76–152; W: 4.0–4.8 Indistinctly defined 12–14 Unknown Kulikovskiy et al. 2016 15 U.grunowii Narrowly fusiform with sub-capitate apices L: 100–380; W: 2.0–4.0 Not or not distinctly separated 11–15.5 Unknown Lange-Bertalot and Ulrich 2014, Kusber et al. 2017 16 U.hunanensis Linear-lanceolate with sub-capitate to rostrate apices L: 62–166; W: 3.3–5.2 Variable 12–14 Unknown Liu et al. 2019a, Williams and Blanco 2019 17 U.hupingensis sp. nov. Lanceolate with rostrate to sub-capitate L: 81–200; W: 5.4–7.0 Completely absent 9.5–11.5 Closed This paper 18 U.japonica Needle-shaped No data Present 11–14 Closed Tuji and Williams 2007, Tuji 2009 19 U.jinbianensis Linear-lanceolate with rostrate to cuneate apices L: 42–91; W: 5.5–7.5 Rectangular to trapezoid fascia 10–11 Closed Liu et al. 2019b 20 U.jumlensis Slightly panduriform with apiculate apices L: 37–48; W: 6.5–9.5 at centre Present 13–14 Closed Jüttner et al. 2000, Williams and Karthick 2021 21 U.macilenta Linear-lanceolate with subrostrate to broadly rounded apices L: 18.5–95; W: 2.5–3.5 Square to rectangular fascia 18–19 Unknown Morales et al. 2014 22 U.menyuanensis sp. nov. Lanceolate with cuneate to rostrate apices L: 60–104; W: 5–7 Not clearly visible due to presence of ghost striae 12–14 Valvocopula closed This paper 23 U.neobiceps sp. nov. Linear-lanceolate with distinct capitate apices L: 202–307; W: 4.5–6.7 Very variable 9–11 Valvocopula closed This paper 24 U.obtusa Linear with rounded apices L: 150–200; W: 5–8 Absent 3–4 Closed Williams and Van de Vijver 2021 25 U.oxyrhynchus Linear with acute, conical to subrostrate apices L: 43–64; W: 6–7 Present, flanked by short striae 13–14 Unknown Morales et al. 2007, Aboal et al. 2003 26 U.pandurata-uniseriata sp. nov. Panduriform with rostrate apices L: 70–116; W: 6.2–8.2 Distinct, fascia-shaped 9–11 Valvocopula closed This paper 27 U.pilum Needle-shaped with sub-capitate apices L: 218–295; W: 5.6–6.3 Rectangular 10–11.5 Unknown Kulikovskiy et al. 2016 28 U.qinghainensis sp. nov. Linear-lanceolate with sub-capitate apices L: 88–223; W: 3.1–5.0 Completely absent 9–11 Valvocopula closed This paper 29 U.ramesii Linear-lanceolate with rostrate apices L: 50–92; W: 8–9 Ellipsoid to rectangular 11–14 Closed Morales et al. 2007, Ohtsuka et al. 2007 30 U.repanda Undulate with broadly rounded apices L: 380–425; W: 5–9 Absent 7–12 Unknown You et al. 2008, Williams 2011 31 U.rhombus Rhombic with sub-capitate apices L: 90–184; W: 4–5.5 Rhomboid, circumscribed by shortened striae 13–14 Unknown Liu et al. 2019a 32 U.rostrata Linear-lanceolate with rostrate apices No data Rectangular No data Closed Tuji and Williams 2007, Tuji 2009 33 U.schroeteri Filiform L: 300–450; W: 2.5–4 Rectangular 15–18 Closed Lange-Bertalot and Ulrich 2014, Williams and Blanco 2019 34 U.splendens Linear with rostrate apices L: 60–300; W: 5–10 Round to oval hyaline portion 6–10 Closed Williams and Van de Vijver 2021 35 U.titicacaensis Lanceolate with subrostrate apices L: 15.5–98.5; W: 4–6.5 Oval to square fascia, asymmetrical 16–18 Unknown Morales et al. 2014 36 U.tooelensis Linear to linear-elliptical with sub-capitate apices L: 14–97.5; W: 3.5–5.5 Rectangular central area on one side 11–15 Closed Graeff et al. 2013 37 U.tortuos Arc L: 120–450; W: 10–12 Present 5–10 Closed Williams and Metzeltin 2004, Williams 2011 38 U.ulna Needle-shaped with sub-capitate apices L: 230–320; W: 6.3–7.7 Absent 9.2–10.4 Closed Lange-Bertalot and Ulrich 2014 39 U.verhaegeniana Linear with acute apices L: 55–90; W: 5–6 Apically rectangular 10–12 Unknown Van de Vijver et al. 2017 40 U.vitrea Lanceolate L: 90–120; W: 4.5–6 Present, variable No data Closed Williams 2020 41 U.wulingensis Narrowly linear-lanceolate L: 153–233; W: 2.7–4.8 Rectangular fascia 12–14 Valvocopula closed Liu et al. 2019a 42 U.xieriverensis sp. nov. 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