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 wuling-biseriata Bing Liu sp. nov. 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 . Figure 35. Ulnaria wuling-biseriata , sp. nov., x 630, LM A-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 . Figure 36. Ulnaria wuling-biseriata , sp. nov., external view, SEM A 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 ). Figure 37. Ulnaria wuling-biseriata , sp. nov., internal view, SEM A 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 ). 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 ). Figure 38. Ulnaria wuling-biseriata , sp. nov., internal view, SEM A 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 ). 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. Ulnaria wuling-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. Ulnaria wuling-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 Ulnaria ulna var. 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. ulna var. 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 Synedra ulna var. spathulifera ).