Cymbella xiaojinensis Li, 2021

Zhang, Yun, Liao, Mengna, Li, Yan-Ling, Chang, Feng-Qin & Kociolek, John Patrick, 2021, Cymbella xiaojinensis sp. nov., a new cymbelloid diatom species (Bacillariophyceae) from high altitude lakes, China, Phytotaxa 482 (1), pp. 55-64 : 58-59

Cymbella xiaojinensis Li sp. nov. Figs 1–21; Fig. 2 is the holotype

LM (Figs 1–14): Valves strongly dorsiventral and triangular. Dorsal margin strongly arched. Ventral margin concave with tumid central part. Valve ends narrowly rounded, not protracted. Length 32–53 μm and width 11–18.5 μm, the maximal length/width ratio ca. 3.5. Axial area narrow, nearly linear, widening slightly at mid-valve on the dorsal side, almost in the middle of the valve. The central area rounded, and dorsal side is larger than ventral side, about 1/2 of the width with valve. Axial area and raphe strongly ventrally displaced. Raphe distinctly lateral, becoming filiform near the distal and strongly reverse-lateral near the proximal ends. Central pores small, ventrally bent, and the terminal fissures dorsally deflected. Striae slightly radiate and become more radiate towards the valve ends. Some short striae arranged on the convex dorsal side in the middle of the valve. 1–2 stigmata appear ventrally from the central nodule, and distant from the middle ventral striae. Striae 7–8/10 μm in the middle and becoming 10–12/10 μm towards the distal, with 16–18 areolae in 10 μm.

In SEM external valve view (Figs 15–18): Striae composed of rounded to elliptical areolae extending to the mantle; drop-like central pores at proximal raphe ends (Fig. 16); roundish/elongated stigma foramina, arranged distant from the foramina of the areolae at central area on ventral side (Fig. 16); Terminal raphe fissures hooked toward dorsal margin of valve (Figs 17, 18).

In SEM internal valve view (Figs 19–21): Striae with internal areolar openings, which are round to elliptical in shape. Distal raphe endings dorsally curved, knob-liked helictoglossae and parallel arranged pole field alveoli (Fig. 21); one or two stigmata alveoli with irregular structures near the shorten striae on the ventral side (Fig. 20).

Etymology: The specific epithet is derived from the name of county where Shadecuo Lake is located.

Type: Praep. Shadecuo-1, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences ( NIGLAS) .

Type locality: Shadecuo Lake (29°44′35.8″N, 101°21′39.8″E), 28th Oct., 2014, surface sediment, leg. Dr. Yulan Luo.