Ulnaria blancoi 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/A3CC9D81-1635-55D8-8EF7-BCA7DDF68E4B
treatment provided by	PhytoKeys by Pensoft
scientific name	Ulnaria blancoi Bing Liu
status	sp. nov.

Treatment

Ulnaria blancoi Bing Liu sp. nov.

Figs 39 View Figure 39 , 40 View Figure 40 , 41 View Figure 41 , 42 View Figure 42 , 43 View Figure 43

Holotype.

Slide JIUDIA202306, specimen circled on slide, illustrated as Fig. 39A View Figure 39 .

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 View Figure 39 ). Valves lanceolate with rostrate to sub-capitate apices (Fig. 39A-M View Figure 39 , see also Figs 40A, C View Figure 40 , 41A View Figure 41 , 42A View Figure 42 ). 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 View Figure 39 , see also Fig. 41B View Figure 41 ). It can be circumscribed by both short marginal striae and isolated areolae (e.g., Fig. 39D-F View Figure 39 , see also Fig. 40D View Figure 40 ), nearly absent (Fig. 39J View Figure 39 , see also Fig. 42B View Figure 42 ) or completely lacking (see Fig. 40A, B View Figure 40 ). 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.

SEM (Figs 40 View Figure 40 - 43 View Figure 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 View Figure 40 , 41A-F View Figure 41 , 42A-D View Figure 42 , closing plates see Fig. 43C View Figure 43 ). Striae uniseriate. Each stria on both sides opposite or alternate, areolae gradually apically elongated from sternum to mantle (Figs 40B, D View Figure 40 , 41B View Figure 41 , 42B-D View Figure 42 ). Central area completely lacking (Fig. 40A, B View Figure 40 ), hyaline region circumscribed by both short marginal striae and isolated areolae (Figs 40C View Figure 40 , 42B-D View Figure 42 ), or hyaline area extending to both margins (Fig. 41B View Figure 41 ). Ocellulimbus composed of ca. 16 pervalvar and 7 transverse rows of porelli. Two horn-like projections protruding over the ocellulimbus (Fig. 40E View Figure 40 , two arrows). One rimoportula located at each pole, externally expressed as a simple hole (Fig. 40E, F View Figure 40 ), internally bilabiate, situated close to sternum at an angle (Fig. 41E, F View Figure 41 ). Valvocopula a closed hoop, surrounding the valve internal margin (Fig. 43A View Figure 43 ). Valvocopula bearing a mostly continuous row of poroids dividing pars interior from pars exterior, located at the midline (Fig. 43B-F View Figure 43 ), lacking ornamentation at both poles (Fig. 43E, F View Figure 43 ). On its advalvar edge, valvocopula has a row of serrated projections, each corresponding internally to a virga (Fig. 43B-E View Figure 43 ).

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.

Ulnaria blancoi 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). Ulnaria splendens ( 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).