42. Diploneis gemmatula (Grunow) Cleve (Figs 106, 107, 211, 212, 218) Basionym: Navicula gemmatula Grunow. Type locality: not given. References: Hustedt 1961–1966, p. 527, figs 1038; Witkowski et al. 2000, p. 187, pl. 91, fig. 14. Morphometrics: Valves 85–120 (50–160) μm long, the width 22.3–31 (23–40) μm in the middle and 28–36 (26–45) μm in the widest portion of the valve, and transapical striae 4–5 (6–7) in 10 μm. Remarks: Diploneis gemmatula is primarily distributed in the warmer oceans, and in Europe, found only in the Mediterranean (Hustedt 1961–1966, Witkowski et al. 2000). It occurred frequently in the coral reefs of Iraq (Al-Handal et al. 2018). It is probably a subtropical taxon with a narrow distribution. It was found rarely as benthic diatoms and an epiphyte on seaweeds along the Seogwipo coast in Jeju Island, representing a new record for South Korea.

Published as part of Joh, Gyeongje, 2021, Distribution and frequent occurrence of diatom taxa (Bacillariophyta) inhabiting warmer oceans in Seogwipo coast of Jeju Island, southernmost Korea, pp. 1-67 in Phytotaxa 517 (1) on page 31, DOI: 10.11646/phytotaxa.517.1.1, http://zenodo.org/record/8061058