The diatom genus Ulnaria (Bacillariophyta) in China Author Liu, Bing https://orcid.org/0000-0002-8516-325X College of Biology and Environmental Sciences, Jishou University, Jishou 416000, China jsulb@outlook.com text PhytoKeys 2023 2023-06-23 228 1 118 http://dx.doi.org/10.3897/phytokeys.228.101080 journal article http://dx.doi.org/10.3897/phytokeys.228.101080 1314-2003-228-1 576A4D0BFA9A5B62B60571F9F54D9E9F Ulnaria pandurata-uniseriata Bing Liu sp. nov. 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 . Figure 77. Ulnaria pandurata-uniseriata sp. nov., x 1000, LM A-J ten valves exhibiting a size diminution series, note the panduriform valve outline C micrograph of holotype specimen. Scale bar: 10 μm . Figure 78. Ulnaria pandurata-uniseriata sp. nov., external view, SEM A, 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 ). Figure 79. Ulnaria pandurata-uniseriata sp. nov., internal view, SEM A, 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 ). 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 ). Figure 80. Ulnaria pandurata-uniseriata sp. nov., internal view, SEM A, 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 ). 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. Ulnaria pandurata-uniseriata is characterized by its panduriform valve outline, rectangular central area, mostly uniseriate striae, and its rostrate apices. It differs from U. jumlensis ( Juettner ) 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 Juettner et al. 2000 , p. 249).