Nitzschia marginulata var. didyma Grunow, 1879

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 : 41

68. Nitzschia marginulata var. didyma Grunow ( Figs 125, 130 )

Type locality: not given.

References: Witkowski et al. 2000. p. 393, pl. 183, figs 4, 5; Lobban et al. 2012. p. 303. pl. 61, figs 2, 3.

Morphometrics: Valves 36–53 (26–41) μm long, 8–10.5 (5–10) μm wide, fibulae 12–15 (12–17) in 10 μm, and transapical striae 25–26 (26–31) in 10 μm.

Remarks: Morphometric dimesions of this variety are adopted from Foged (1984), Podzorski & Håkansson (1987) and Lobban et al. (2012). Nitzschia marginulata var. didyma was found in many regions: Cuba ( Foged 1984), Gambia ( Foged 1986), Palawan of the Philippine ( Podzorski & Håkansson 1987), Viti Levu ( Fiji) ( Foged 1987), Puerto Rico ( Navarro et al. 1989), Guam ( Lobban et al. 2012), Florida Bay ( Wachnicka et al. 2013), Mexico ( Lopez-Fuerte et al. 2015), and Moen Island in Chuuk Lagoon ( Park et al. 2018). Although this taxon was reported only in three checklists published in the Britain ( Hendey 1954, 1974, Hartley et al. 1986), it is tropical one distributed in warmer regions. This variety is not only morphologically similar to Nitzschia carnicobarica Desikachary & Prema ( Witkowski et al. 2000, pl. 373, figs 9, 10), but also has many overlapping parts in the morphology and dimensions, making it difficult to detect the difference.

It was frequently found as an epiphyte on seaweeds in the lagoon and pseudo-lagoons along the Seogwipo coast in Jeju Island, and represents a new record for South Korea.

Figures

FIGURES 121–134. Diatom taxa of Seogwipo coast in Jeju Island (13). Figs 121, 122. Amphora bigibba var. interrupta. Figs 123, 124. A. staurohyalina. Figs 125, 130. Nitzschia marginulata var. didyma. Figs 126, 127. Seminavis cf. pusilla. Figs 128, 129. Nitzschia composita. Figs 131, 132. Seminavis latior. Fig. 133. Tetramphora intermedia. Fig. 134. T. decussata. Scale bars = 10 μm.