Ulnaria neobiceps 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/AEFF919F-8334-5F81-B2E4-38D9EC4E5846
treatment provided by	PhytoKeys by Pensoft
scientific name	Ulnaria neobiceps Bing Liu
status	sp. nov.

Treatment

Ulnaria neobiceps Bing Liu sp. nov.

Figs 48 View Figure 48 , 49 View Figure 49 , 50 View Figure 50 , 51 View Figure 51 , 52 View Figure 52 , 53 View Figure 53

Holotype.

Slide JIUDIA202308, specimen circled on slide, illustrated as Fig. 48A View Figure 48 .

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 View Figure 48 ). Valves linear-lanceolate with distinct capitate apices (Fig. 48A-K View Figure 48 , see also Figs 49A View Figure 49 , 50A View Figure 50 ). 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 View Figure 48 ), can be circumscribed by both short marginal striae and isolated areolae (e.g., Fig. 48B, C, G, J View Figure 48 ), nearly absent (Fig. 48H View Figure 48 ) or completely lacking (Fig. 48A, D, E, I View Figure 48 ). 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.

SEM (Figs 49 View Figure 49 - 53 View Figure 53 ). Valve characterized by a series of relatively wide virgae and interconnected with vimines (Fig. 49B-F View Figure 49 ). Central area completely lacking (Fig. 49B View Figure 49 ), hyaline area circumscribed by both short marginal striae and isolated areolae (Figs 50B View Figure 50 , 51A, C, D View Figure 51 ), or hyaline area extending to both margins (Fig. 51B View Figure 51 ). Striae uniseriate, on both sides of sternum, opposite or alternate, areolae gradually become elongated from sternum to mantle (Figs 50B-F View Figure 50 , 51A-D View Figure 51 ). Ocellulimbus composed of ca. 24 pervalvar and 8 transverse rows of porelli. Two horn-like projections protruding over the ocellulimbus (Fig. 52D View Figure 52 , two arrows). One rimoportula located at each pole, externally expressed as a simple hole (Fig. 49F View Figure 49 ), internally bilabiate, situated close to sternum at an angle (Fig. 50D, F View Figure 50 ). Valvocopula closed, surrounding the valve internal margin (Fig. 52A View Figure 52 ), bearing a mostly continuous midline row of poroids dividing pars interior from pars exterior (Figs 52B-F View Figure 52 , 53A-F View Figure 53 ), lacking ornamentation at both poles (Figs 52D, F View Figure 52 , 52C-F View Figure 52 ). On its advalvar edge, valvocopula has a row of serrated projections, each corresponding internally to a virga (Fig. 52B, C, E View Figure 52 ). Shelf-like projections present at pars interior of each apex (Fig. 53C-F View Figure 53 , two arrows, respectively).

Etymology.

The epithet biceps has been occupied by Ulnaria biceps ( 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.

Ulnaria neobiceps , 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.

Ulnaria neobiceps 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 Synedra capitata ) whereas the apices of U. neobiceps are rounded-capitate. Moreover, U. neobiceps has very variable central area while U. capitata lacks central area.