Ardissonea formosa (Hantzsch) Grunow

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 : 11

8. Ardissonea formosa (Hantzsch) Grunow ( Figs 46–49 )

Basionym: Synedra formosa Hantzsch.

Type locality: East Indies .

References: Hustedt 1931 –1959, p, 233, fig. 720; Witkowski et al. 2000, p. 43, pl. 30, fig. 12; Lobban et al. 2012, p. 259, pl. 15, figs 4, 5, pl. 16, figs 1, 2; Stidolph et al. 2012, pl. 8, fig. 158, pl. 27, figs 129–131, pl. 45, fig. 30.

Morphometrics: Valves 320–380 (200–720) μm long, 19–20 (15–25) μm wide, transapical striae 8–9 (9–10) in 10 μm.

Remarks: According to Hustedt (1931 –1959) and Witkowski et al. (2000), the valves of this taxon are linear or often somewhat retracted in the middle, but the specimens collected in this area are not only smaller in size, but more or less lanceolate in outline and often slightly swollen in the middle. There are differences in the size of the valve (115–373 μm vs 200–720 μm), whereas transverse striae are a bit coarse. The specimens reported from the Galapagos Islands and the Azores Islands ( Stidolph et al. 2012) were the same as those of this locality, distinctly lanceolate in valve outlines as collected locally. It is unclear whether this is simple morphological variations within the species.

This taxon is distributed in the coast of warmer oceans, and, in Europe, only in the Mediterranean ( Hustedt 1931 – 1959, Witkowski et al. 2000). It has been reported from Fujian coast of China ( Jin et al. 1985), from Fiji ( Foged 1987), from Palawan of Philippines ( Podzorski & Håkansson 1987), from coral-reef and farmer-fish areas of Guam, and in tropical areas, Puerto Rico in Caribbean Sea, the Bahamas in the Atlantic Ocean, and Mahé Island of the Seychelles ( Hein et al. 2008, Lobban et al. 2012), from the Yucatan Peninsula in Gulf of Mexico ( Merino-Virgilio et al. 2013), and bloomed in the Gulf of Mannar of India ( Gopakumar et al. 2009), the Mediterranean ( Álvarez-Blanco & Blanco 2014), Chuuk Lagoon of Micronesia ( Park et al. 2018). It is typical taxon preferring warmer oceans. This species was encountered rarely as an epiphyte on seaweeds of rock pools along the Seogwipo coast in Jeju Island.

Figures

FIGURES 46–57. Diatom taxa of Seogwipo coast in Jeju Island (6). Figs 46–49. Ardissonea formosa. Fig. 50. Ardissonea sp. Figs 51–54. Toxarium hennedyanum. Figs 55–57. Licmophora pfannkucheae. Scale bars = 10 μm.