Surirella ectorii Bing Liu & Rioual, 2025

Surirella ectorii Bing Liu & Rioual sp. nov.

Figs 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6

Holotype.

Specimen circled on slide DIA 2025001 About DIA (= Fig. 4 B View Figure 4 ), deposited in the Herbarium of Jishou University ( JIU), China. Registration: http://phycobank.org/105636. 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. 4 View Figure 4 ). Valve outlines nearly elliptical with almost isopolar headpole and footpole. Valve dimensions (n = 24): length range 44–69 μm, width range 34–45 μm at its widest region. Costa-stria bundles ( CSBs) distinct, alternating with over-fibula ribs ( OFRs) from pole to pole (labelled in Fig. 4 E View Figure 4 ). CSBs radiate throughout the valve surface. Fibulae visible, short (judged by OFRs, labelled in Fig. 4 E View Figure 4 ), 4–6 in 10 μm. A marginal row of costae produced on the wall of raphe canal (e. g., Fig. 4 B View Figure 4 , arrows), 16–18 in 10 μm.

SEM (Figs 5 View Figure 5 , 6 View Figure 6 ). Externally, raphe canal located directly on mantle (Fig. 5 A – C View Figure 5 ), and wall of raphe canal bearing a marginal row of costae (Fig. 5 C View Figure 5 , arrows, Fig. 5 F View Figure 5 , double-headed arrow). Distal raphe endings straight, interrupted at both headpole and footpole (Fig. 5 D, E View Figure 5 ). Surface costae mostly slightly raised, some reaching valve midline (Fig. 5 C View Figure 5 ). Each CSB often composed of ca. 2–5 costae and 3–6 striae (Fig. 5 F View Figure 5 ). Outside openings of areolae slit-like (Fig. 5 F View Figure 5 ). Striae multiseriate, composed of ca. 2–5 rows of areolae (Figs 5 F View Figure 5 , 6 View Figure 6 ), 15–19 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 (e. g., Fig. 5 D – F View Figure 5 ). Internally, wall of raphe canal slightly growing into cell cavity, whereas portulae visible (Fig. 6 A, B View Figure 6 ). Fibulae slim, short, sometimes doubled or tripled (Fig. 6 F View Figure 6 , arrows), spanning ca. 1 / 4 of valve width, not extending to valve midline except at two poles. Marginal trough-like depressions present around entire raphe canal (Fig. 6 D View Figure 6 , black dotted line). Raphe continuous at headpole (Fig. 6 C View Figure 6 , arrow) whereas interrupted at footpole (Fig. 6 D View Figure 6 , two arrows). 2–5 portulae produced between two adjacent fibulae (Fig. 6 F View Figure 6 , arrows). Inner openings of areolae rounded, not rimmed.

Etymology.

Named after the late diatomist from Luxembourg, Luc Ector (1962–2022), for his dedication to diatom taxonomy and his help with our studies of diatoms in China.

Vernacular name.

The Chinese name is “ 埃氏双菱藻 ”.

Ecology and distribution.

Surirella ectorii was commonly found on the sediment at the surface of the stones collected in Lake Qinghai but not in large abundance. In the samples it is found in association with S. brightwellii . So far, S. ectorii has only been found in the type locality and may therefore be considered as a brackish diatom endemic to Lake Qinghai.