Amphora arenaria Donkin, 1858

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 : 36

57. Amphora arenaria Donkin ( Figs 101, 110 , 207–210 )

Synonym: Amphora arenaria var. typica Cleve.

Type locality: Along the southern portion of Northumberland shore, England .

References: Witkowski et al. 2000, p. 130, pl. 168, fig. 14; Wachnicka & Gaiser 2007, p. 435, fig. 188; Hein et al. 2008, p. 41, pl. 19, figs 1, 2; Lobban et al. 2012, p. 297, pl. 53, figs 5, 6, pl. 54, figs 1, 2.

Morphometrics: Valves 84–95 (52–118) μm long, 17–24 (8–18) μm wide, and transapical striae 22–23 (20–26) in 10 μm.

Remarks: Amphora arenaria is very close to A. obtusa Gregory in morphology and dimensions, but the former lacks intercalary bands in the girdle and carries a narrow girdle band, in addition to a slightly sinuate ventral margin, whereas the latter contains has straight margins ( Wachnicka & Gaiser 2007, Lobban et al. 2012). The two species exhibit a large difference in strial density, but broadly overlap in the range of 21–28 in 10 μm. However, it is difficult to distinguish according to strial density ( Lobban et al. 2012).

This taxon is widespread on the coasts of European Atlantic Ocean ( Witkowski et al. 2000), and is frequently found in warmer oceans: Sesoko Island of Okinawa, Japan ( Nagumo & Mayama 2000), the Florida Bay ( Wachnicka & Gaiser 2007), the Bahamas of the southeastern Florida ( Hein et al. 2008), and Guam and Chuuk Lagoon of the western Pacific Ocean ( Lobban et al. 2012, Park et al. 2018). It is distributed along the tropical and subtropical coasts. In South Korea, it is rarely epiphytic on seaweeds along the Seogwipo coast in Jeju Island.

Figures

FIGURES 101–110. Diatom taxa of Seogwipo coast in Jeju Island (11). Figs 101, 110. Amphora arenaria. Figs 102, 103. Navicula perrhombus. Figs. 104. Cymatoneis circumvallata. Fig. 105. C. margarita. Figs 106, 107. Diploneis gemmatula. Figs 108, 109. D. notabilis. Scale bars = 10 μm.

FIGURES 203–212. Diatom taxa of Seogwipo coast in Jeju Island (21). Figs 203–206. Amphora staurohyalina: external (Figs 203, 204) and internal view (Figs 205, 206) of valves, double striation, hyaline thickened stauros in the middle parts of dorsal side, and apical folds on valve. Figs 207–210. Amphora arenaria: dotted striation and arcing central raphe endings of the external valves (Figs 207–219), internal view of valve (Fig. 210). Figs 211, 212. Diploneis gemmatula: external view of valve. Figs 203–212: SEM. Scale bars = 20 μm (Fig. 211), 10 μm (Figs 207, 210), 5 μm (Figs 203, 206, 209), 2 μm (Figs 204, 205, 208, 212).