Hannaea mongolica Glushchenko, Kulikovskiy, Q. Liu & Kociolek, sp. nov.

(Figs 7-10)

HOLOTYPE. — Slide no 00060; illustrated in Fig. 8A, in collection of Maxim Kulikovskiy at the Herbarium of the Institute of Plant Physiology Russian Academy of Science, Moscow, Russia, leg. M.S. Kulikovskiy and E.S. Gusev.

TYPE LOCALITY. — Mongolia, Terkhiin Tsagaan Lake, Khangai Mountains, periphyton, 13.VIII.2011 (46°42.371’N, 096°39.862’E).

ETYMOLOGY. — The specific epithet “ mongolica ” refers to the name of the country where this species was observed.

DISTRIBUTION. — Type locality and slides no 02496, 02694, 003097, 03098. Mongolia: Tuul River, Herlen River (as Hannaea ? in Metzeltin et al. 2009: pl. 9, figs 1-8).

DESCRIPTION

Valves

Arcuate, smoothly tapering to the ends with capitate to rostrate apices, length 39.0-93.5 µm, breadth 6.5-8.0 µm.

Axial area

Narrow, linear. Central area is expanded unilaterally on the concave margin, large, with ghost striae present. Striae parallel, 17-18 in 10 µm.

SEM, external views (Fig. 9)

Valve face is flat (Fig. 9 A-C). Striae biseriate going from valve face to the mantle. No silica ridge is evident between valve face and mantle. Axial area is very narrow. Central area is unilaterally expanded, large, swollen on the ventral side of the valve with evident ghost striae (Fig. 9B, C). Small circle or slit-like openings of rimoportulae are present on each valve end. Ocellimbi are present on mantle in each valve ends (Fig. 9D, E). Spines were not detected (Fig. 9 A-C).

SEM, internal views (Fig. 10)

Striae biseriate, lying in depressions. Striae extend onto the mantle. Axial area is narrow. Central area is unilaterally- expended, large, located on the concave side of the valve with evident ghost striae (Fig. 10 A-C). One rimoportula is present at each valve apex. Ocellimbi are present at each valve end, positoned on mantle (Fig. 10D, E).