Cocconeis delicata A. Schmidt

Joh, Gyeongje, 2021, Distribution of the genus Cocconeis (Bacillariophyceae) along the Seogwipo coast of Jeju Island, South Korea, Phytotaxa 528 (3), pp. 149-179 : 155-157

9. Cocconeis delicata A. Schmidt ( Figs 38–41 )

Basionym: Schmidt et al. 1894b, pl. 196, fig. 24.

References: Suzuki et al. 2007, p. 38, figs 15, 16; Riaux-Gobin et al. 2017, p. 52, figs 8, 34–38.

Description: Valves elliptical, 21–35 μm long, 14–25 μm wide. SV: sternum elliptical, central area not developed. Transapical striae radiate towards the apices, crossed by hyaline and zigzag longitudinal rows, 18–22 in 10 μm, areolae on a stria transversely elongated, 9–11 in 10 μm. RV: raphe weakly sigmoid, sternum very narrow. Central area transversely hyaline, occupying the short width of the middle field. Transapical striae radiate towards the apices, 18–22, with 16–23 areolae in 10 μm of stria.

Remarks: This species was originally identified from Yokohama materials by Schmidt et al. (1894b), but very few examples have been reported since. Meister (1935) and Suzuki et al. (2007) reported this species on the coast of Japan, and Riaux-Gobin et al. (2017) described the species in detail, using materials obtained from Nagasaki, Japan. The species was rarely encountered along the Seogwipo coast of Jeju Island. It is herein newly described for South Korea.

Figures

FIGURES 25–44. LM micrographs of Cocconeis species (2). Figs 25, 26. Cocconeis cf. diruptoides, RV (Fig. 25) and SV (Fig. 26). Figs 27–32. C. dirupta var. dirupta, SVs (Figs 27–31) and RV (Fig. 32). Figs 33–37. C. dirupta var. flexella, SVs (Figs 34–36) and RVs (Figs 33, 37). Figs 38–41. C. delicata, RVs (Figs 38) and SVs (Figs 39, 40, 41). Figs 42–44. C. convexa, SVs (Figs 42, 43) and RV (Fig. 44). Scale bar = 10 μm (Figs 25–44).