Cymbopleura huohuaensis Guo & Meng & Kociolek & Yang & Li 2022

Cymbopleura huohuaensis Y.-L. Li, sp. nov. (Figs 1–11)

Description:— LM (Figs 1–4): Valves linear-subelliptical, slightly asymmetrical about the apical axis, dorsal and ventral margins similarly arched or dorsal margin more inflated, ends slightly truncate to obtusely rounded. Length 51.0–72.0 μm, width 12.0–14.0 μm, length/width ratio 4.2–5.2, median 5.0 (n = 30). Raphe lateral, appearing strongly reverse-lateral near the central ends. External central raphe ends deflected gently towards the ventral side and tipped with slightly inflated pores. External terminal raphe fissures hooked towards dorsal margin. Axial area lanceolate, broadening gradually towards valve centre. Central area linear-lanceolate, extremely asymmetrical, occupying nearly 1/4–1/3 of the valve width, with 2–6 slightly shortened central dorsal striae, 6–9 markedly shortened central ventral striae. Striae slightly radiate, ventral striae almost parallel at the poles, dorsal striae occasionally parallel at the ends, indistinctly punctate-lineate. Striae in the middle portion (dorsal) 9–10 in 10 μm, up to 15 in 10 μm toward the ends. Areolae not visible.

SEM: Valve exterior (Figs 5–8): Raphe undulate with central raphe ends, slightly dilated and bent ventrally (Figs 5, 8), terminal fissures hooked, deflected towards the dorsal side, terminating between shortened striae extending around the apices (Figs 6, 7). Striae uniseriate, slightly radiate throughout (Figs 5–8). Areolae mostly slit-like, partly T-shape, V-shape or irregularly-shaped along the axial area and central area, 30–50 in 10 μm (Figs 6–8). Stigmata and apical pore fields absent (Figs 5–8).

Valve interior (Figs 9–11): Striae formed by dotted, uniseriate areolae surrounded by spiral protrusions (Figs 9–11). Internal raphe opening continuous without intermissio and valve centre with distinct central nodule (Figs 9, 10), terminal raphe ends offset, bent slightly towards the dorsal margin, and terminate in small, knob-like helictoglossae and shortened striae (Fig. 11). Stigmata absent (Figs 9–11).

Type: — CHINA. Sichuan Province: Huohua Lake, Jiuzhaigou Nature Reserve, HHL1, 33°16′44″ N, 103°88′49″ E, elevation 2187 m asl, Xiao Zhou, 10th November 2008 (holotype HHL2008111001! in Coll. Yan-Ling Li, Yunnan University, Kunming, China = Fig. 3).

Etymology: — huohuaensis, referring to Huohua Lake, the type locality from which the new species is described.

Ecology: —This species was associated with Achnanthidium minutissimum (Kützing) Czarnecki (Czarnecki 1994: 157), Encyonopsis microcephala (Grunow) Krammer (1997b: 91), Cymbopleura kuelbsii (Kützing) Krammer (2003: 94), Delicatophycus deliculata (Kützing) M.J. Wynne (2019:1), and several unidentified species of Caloneis Cleve (1894: 5), Cyclotella (Kützing) Brébisson (1838: 19), Cymbella, Fragilaria Lyngbye (1819: 182), and Gomphonema Ehrenberg (1832: 87).