Surirella qinghainensis Bing Liu & Rioual, 2025

Surirella qinghainensis Bing Liu & Rioual sp. nov.

Figs 7 View Figure 7 , 8 View Figure 8 , 9 View Figure 9 , 10 View Figure 10 , 11 View Figure 11

Holotype.

Specimen circled on slide DIA 2025002 About DIA (= Fig. 7 B View Figure 7 ), deposited in the Herbarium of Jishou University ( JIU), China. Registration: http://phycobank.org/105637. GoogleMaps

Type locality.

China. Qinghai Province, Lake Qinghai, a sampling site near the lakeshore   GoogleMaps , 36°50'34"N, 99°42'39"E, 3210 m asl., collected by Bing Liu, July 19 th, 2019.

Description.

LM (Fig. 7 View Figure 7 ). Valve outlines ovate with broadly rounded headpole and cuneate footpole. Valve dimensions (n = 34): length range 38–57 μm, width range 31–50 μm at its widest region. Costa-stria bundles ( CSBs) distinct, alternating with over-fibula ribs ( OFRs) from pole to pole (labelled in Fig. 7 E View Figure 7 ). CSBs radiate throughout valve surface. Fibulae visible, short (judged by OFRs, labelled in Fig. 7 E View Figure 7 ), 4–6 in 10 μm. A marginal row of costae produced on the wall of raphe canal (e. g., Fig. 7 B View Figure 7 , arrows), 16–18 in 10 μm.

SEM (Figs 8 View Figure 8 – 11 View Figure 11 ). Externally, raphe canal located directly on mantle (Fig. 8 A, B View Figure 8 ), and wall of raphe canal bearing a marginal row of costae (Fig. 8 B View Figure 8 , arrows; Fig. 8 E View Figure 8 , double-headed arrows). Valve surface presents three differentiable areas (labelled A 1, A 2, and A 3 in Fig. 8 B View Figure 8 ). Distal raphe endings straight, interrupted at both headpole and footpole (Fig. 8 C, D View Figure 8 ). Surface costae mostly slightly raised, not reaching valve midline except at two poles (Fig. 8 A, B View Figure 8 ). Each CSB often composed of ca. 2–4 costae and 3–5 striae (Fig. 8 F View Figure 8 ). Outside openings of areolae slit-like (Fig. 8 D View Figure 8 ). Striae multiseriate (sometimes becoming uniseriate at valve middle, Fig. 9 A, D View Figure 9 ), composed of ca. 2–5 rows of areolae (Figs 8 D View Figure 8 , 9 View Figure 9 , 10 View Figure 10 ), 16–20 in 10 μm (measured at the valve margin from SEM images, n = 3). Surface siliceous warts and reticulate thickenings produced on costae and between adjacent two costae, respectively (Fig. 8 A-F View Figure 8 ). Each mantle sinking corresponding to each over-fibula rib (Fig. 9 C View Figure 9 , arrows). Internally, wall of raphe canal not growing conspicuously into cell cavity, leaving portulae visible (Fig. 10 View Figure 10 ). Fibulae slim, much shorter, spanning ca. 1 / 8 of valve width, far away from valve midline except at two poles. Marginal trough-like depressions present around entire raphe canal (Fig. 10 View Figure 10 ). Raphe continuous at headpole (Fig. 10 C View Figure 10 , arrow) whereas interrupted at footpole (Fig. 10 B View Figure 10 , two arrows). 2–4 portulae produced between two adjacent fibulae (Fig. 10 E, F View Figure 10 , arrows). Inner openings of areolae rounded, rimmed (Fig. 10 B – F View Figure 10 ).

Etymology.

Named after Lake Qinghai, where this species was found.

Vernacular name.

The Chinese name is “ 青海湖双菱藻 ”.

Ecology and distribution.

Surirella qinghainensis was commonly found in the surface sediment on the surface of the stones collected in Lake Qinghai with S. brightwellii and S. ectorii . It is more frequent than S. ectorii but less than S. brightwellii . So far, S. qinghainensis has only been found in the type locality and can be considered a brackish diatom species endemic to Lake Qinghai.