Cocconeis heteroidea Hantzsch, 1863

Joh, Gyeongje, 2021, Distribution of the genus Cocconeis (Bacillariophyceae) along the Seogwipo coast of Jeju Island, South Korea, Phytotaxa 528 (3), pp. 149-179 : 161

14. Cocconeis heteroidea Hantzsch ( Figs 77, 78 )

Basionym: Rabenhorst 1863, p. 21, pl. 6 A, fig. 10.

References: Hustedt 1933, p. 256, fig. 811; Suzuki et al. 2001a, p. 131, figs 1–28; Lobban et al. 2012, p. 287, pl. 40, figs 6, 7, pl. 41, figs 1–3.

Description: Valves broadly elliptical to almost circular, 36–55 μm long, 30–47 μm wide. SV: sternum broadly linear in outline, but distinctly sigmoid. Transapical striae radiate towards the apices, 30, interrupted by a broad longitudinal furrow, and four longitudinal hyaline lines between sternum and the margins, appearing like some longitudinal folds, areolae in a stria transapically elongated. RV: raphe strongly sigmoid, and sternum narrow. Central area small and circular. Valve deeply buried to apical direction between the raphe and the margins, the apical central parts looking prominent in the sigmoid ridge. Transapical striae radiate towards the apices, 23 in 10 μm.

Remarks: This taxon is common in the Mediterranean Sea ( Hustedt 1933, Witkowski et al. 2000, Majewska et al. 2013), and was reported for the East Sea of Russia ( Orlova et al. 2009) as well as for islands of the Pacific Ocean, Bahamas, and Caribbean Sea ( Lobban et al. 2012). It is widely distributed along warmer coasts. In South Korea, it was recorded as plankton off the coast of Jeju Island ( Lee et al. 1990), as epiphytes on Zostera in the coast of Geoje Island ( Chung & Lee 2008), and in this survey, occurred rarely as epiphytes on seaweeds from small rock pools in Seogwipo coast (St. 2).

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).