Cocconeis dirupta var. flexella (Janisch & Rabenhorst) Grunow, 1880

Joh, Gyeongje, 2021, Distribution and frequent occurrence of diatom taxa (Bacillariophyta) inhabiting warmer oceans in Seogwipo coast of Jeju Island, southernmost Korea, Phytotaxa 517 (1), pp. 1-67 : 27

36. Cocconeis dirupta var. flexella (Janisch & Rabenhorst) Grunow ( Figs 82–84 )

Type locality: not given.

References: Hustedt 1931 –1959, p. 355, figs 809d–i; Witkowski et al. 2000. p. 105, pl. 39, figs 6, 7, pl. 51, figs 3–8; Stidolph et al. 2012, pl. 22, figs 25, 30.

Morphometrics: Valves 10–23 (15–60) μm long, 5–14 (9–50) μm wide, transapical striae 15–22 (18–27) in 10 μm of sternum valve, and 24–28 (18–24) in 10 μm of raphe valve.

Remarks: This variety is distinguished from the nominate variety by sigmoid axial area of the sternum valve. Two forms (large and small) were detected in the micrographs of Witkowski et al. (2000). The local specimens are relatively smaller than those reported previously.

This variety was collected from the Adriatic Sea, in the Mediterranean and Namibia of the western Atlantic Ocean ( Witkowski et al. 2000). It has been reported from many tropical regions: Baja California Peninsula of Mexico ( Siqueiros-Beltrones & Romero 2004), Mascarene Islands in the western Indian Ocean (Riaux-Robin et al. 2011), the Galapagos Islands ( Stidolph et al. 2012), and Guam and Society Islands of the Pacific Ocean, Mahé Island of the Indian Ocean, Puerto Rico and Caribbean Sea ( Lobban et al. 2012). It is a diatom taxon inhabiting warmer coasts. In South Korea, it is generally epiphytic on seaweeds along the Seogwipo coast, representing a new record for South Korea.

Figures

FIGURES 78–90. Diatom taxa of Seogwipo coast in Jeju Island (9). Fig. 78. Cocconeiopsis orthoneoides. Fig. 79. Navicula semiarea. Figs 80, 81. Fallacia vittata. Figs 82–84. Cocconeis dirupta var. flexella. Figs 85, 86. Achnanthes citronella. Figs 87, 88. Cocconeis pellucida. Figs 89, 90. Planothidium quarnerensis f. rhombica. Scale bars = 10 μm.