Ulnaria xieriverensis Bing Liu, 2023

Liu, Bing, 2023, The diatom genus Ulnaria (Bacillariophyta) in China, PhytoKeys 228, pp. 1-118 : 1

publication ID	https://dx.doi.org/10.3897/phytokeys.228.101080
persistent identifier	https://treatment.plazi.org/id/72D21C66-FB8F-5BF5-802A-8EE629318A23
treatment provided by	PhytoKeys by Pensoft
scientific name	Ulnaria xieriverensis Bing Liu
status	sp. nov.

Treatment

Ulnaria xieriverensis Bing Liu sp. nov.

Figs 73 View Figure 73 , 74 View Figure 74 , 75 View Figure 75 , 76 View Figure 76

Holotype.

Slide JIUDIA202313, specimen circled on slide, illustrated as Fig. 73A View Figure 73 .

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 View Figure 73 ). Valves generally linear (i.e., valve margins almost parallel), slightly undulate in larger specimens (Fig. 73A-C View Figure 73 , see also Fig. 76B, C View Figure 76 ), parallel in smaller specimens (Fig. 73D-H View Figure 73 , see also Figs 74A View Figure 74 , 75A View Figure 75 , 76A View Figure 76 ). 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.

SEM (Figs 69 View Figure 69 - 72 View Figure 72 ). Valve characterized by relatively wide virgae, interconnected with vimines, closing plates affixed with a few struts to the areolar wall (Fig. 74B-D View Figure 74 ). Ocellulimbus composed of ca. 16 pervalvar and 9 transverse rows of porelli. Two horn-like projections protruding over the ocellulimbus (Fig. 74E, F View Figure 74 , 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 View Figure 75 ). One rimoportula present at each pole, externally expressed as a simple hole (Fig. 74C-F View Figure 74 ), internally bilabiate, situated close to sternum (Fig. 75C, E, F View Figure 75 ), sometimes displaced, against mantle (Fig. 75D View Figure 75 ). Central area completely lacking (Figs 74A, B View Figure 74 , 75A, B View Figure 75 , 76A-D View Figure 76 ). Valvocopula a closed hoop (Fig. 76A-C View Figure 76 ). Valvocopula bearing a mostly continuous row of poroids dividing pars interior from pars exterior, located at the midline (Fig. 76D-F View Figure 76 ), lacking ornamentation at both poles (Fig. 76E, F View Figure 76 ). On its advalvar edge, valvocopula has a row of serrated projections, each corresponding internally to a virga (Fig. 76D, E View Figure 76 , three arrows, respectively).

Etymology.

Named after Xie River, where the species was found.

Ecology and distribution.

Epilithic in a mountain stream with oligotrophic waters. Ulnaria hupingensis 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.

Ulnaria xieriverensis is characterized by its linear valve outline, absence of central area, and rostrate apices. It differs from U. hupingensis by its linear valve outline.