Cocconeis cf. callosa Meister, 1937

Joh, Gyeongje, 2021, Distribution of the genus Cocconeis (Bacillariophyceae) along the Seogwipo coast of Jeju Island, South Korea, Phytotaxa 528 (3), pp. 149-179 : 152

1. Cocconeis cf. callosa Meister ( Figs 79–83 )

Basionym: Meister 1937, p. 266, pl. 8, fig. 11.

Reference: Riaux-Gobin et al. 2017, p. 57, figs 9, 44–51.

Description: Valves rather circular, 27–54 μm long, 21–49 μm wide. SV: sternum narrow and bent in opposite directions at the apices, forming a distinct sigmoid curvature. Central area not developed, but only a few areolae missing in the middle to form a small hyaline space. Transapical striae radiate in the middle and strongly radiate towards the apices, 13–15 in 10 μm, formed by coarse areolae, with 10–11 areolae in 10 μm of stria. RV: raphe and sternum strongly sigmoid, with opposite curvatures of the terminal ends, both ends of raphe and sternum distant from the apices. Central area extended transversely in a narrow hyaline area not reaching the margins. Transapical striae, 13–14 in 10 μm distinctly areolae, with 12–16 in 10 μm of stria.

Remarks: Although there was no type specimen of the species, and the morphology of RV was not even described in the original statement, Riaux-Gobin et al. (2017) searched the Meister’s collections, and erected Cocconeis cf. callosa as a legitimate taxon. This species has only been reported from the type locality, Nagasaki in Japan. In the Seogwipo coast of Jeju Island, very rare as epiphytes from a small rock pool (St. 2), representing a new record for South Korea.

Figures

FIGURES 77–83. LM micrographs of Cocconeis species (6). Figs 77, 78. Cocconeis heteroidea, RV (Fig. 77) and SV (Fig. 78). Figs 79–83. C. cf. callosa, RVs (Figs 79, 82) and SVs (Figs 80, 81, 83). Scale bar = 10 μm (Figs 77–83).