Cocconeis schmidtii Heiden, 1928

Joh, Gyeongje, 2021, Distribution of the genus Cocconeis (Bacillariophyceae) along the Seogwipo coast of Jeju Island, South Korea, Phytotaxa 528 (3), pp. 149-179 : 166

20. Cocconeis schmidtii Heiden ( Figs 53–56 , 106, 107 )

Basionym: Heiden and Kolbe 1928, p. 587.

Reference: Simonsen 1992, p. 33, pl. 33, figs 1–5, pl. 34, figs 1–3.

Description: Valves broadly elliptical, 17–61 μm long, 11–44 μm wide. SV: sternum narrow. Central area very small and circular, but indistinct in small-sized valves. Transapical striae parallel in the middle, strongly radiate towards the apices, 15–20 in 10 μm, interrupted by zig-zag longitudinal hyaline lines, areolae in a stria transversely elongated, 7–12 in 10 μm. RV: valve surface slightly depressed concentrically in the submarginal area. Raphe straight and linear, the terminal ends of the raphe distant from apices without any areolation, sternum narrow. Central area small and circular. Transapical striae parallel in the middle, strongly radiate towards the apices, 13–17 in 10 μm, with 13–23 circular areolae in 10 μm of stria.

Remarks: The species is very similar to Cocconeis shikinensis in morphology. If one addition is made to the differences between the two species, the transapical striae of the former are strongly radiate towards the ends of valve, which is distinct from the latter.

Occurring in the type locality, Kerguelen Island, in the Antarctica of the Indian Ocean. This taxon has been described from the type locality of Kerguelen Island in the Subantarctic of the Indian Ocean ( Simonsen 1992), in coastal areas of King George Island, and the western Antarctic Peninsula ( Lange et al. 2018). This taxon was encountered frequently as epiphytes along the Seogwipo coast; it is herein newly described for South Korea.

Figures

FIGURES 45–56. LM micrographs of Cocconeis species (3). Figs 45–48. Cocconeis scutellum, RV (Fig. 45) and SVs (Figs 46–48). Figs 49–52. C. shikinensis, SVs (Figs 49, 52) and RVs (Figs 50, 51). Figs 53–56. C. schmidtii, RVs (Figs 54, 56) and SVs (Figs 53, 55). Scale bar = 10 μm (Figs 45–56).

FIGURES 106, 107. SEM micrographs of Cocconeis species (11). Figs 106, 107. Cocconeis schmidtii, the internal view of SV (Fig. 106), the external view of RV (Fig. 107). Scale bars = 2 μm (Figs 106, 107).