Epithemia guettingeri (Krammer) Lobban & J.S. Park, 2018

Park, Joon Sang, Lobban, Christopher S. & Lee, Kyun-Woo, 2018, Diatoms associated with seaweeds from Moen Island in Chuuk Lagoon, Micronesia, Phytotaxa 351 (2), pp. 101-140 : 132

144. Epithemia guettingeri (Krammer) Lobban & J.S. Park , comb. nov. Figs 171–173

References: Krammer (1988), p. 168, figs 129–138; Navarro & Lobban (2009) (as R. gibberula ).

Samples: Moen2_ Padina

Dimensions: 21.7–28.3 μm long, 6.4–6.5 μm wide; 10–12 striae in 10 μm.

Comments: Krammer (1988), noted that there are two Rhopalodia species with large apical costae (i.e., a costa running across the striae in the ventral part of the valve), but that both had been identified as R. gibberula . In R. pacifica Krammer in Lange-Bertalot & Krammer, the apical costa can be seen in SEM only from the inside and there are no areolae on it (appearing as a hyaline band in external SEM view), and the striae are easily visible, 15–18 in 10 μm. In contrast, in R. guettingeri Krammer the apical costa can be seen in SEM from both sides, it has areolae on it, and the striae are hardly visible in LM, 40–46 in 10 μm. On this basis, the external SEM view in Navarro & Lobban (2009) (specimen from Yap) is R. guettingeri and was so listed for Guam (without further illustrations) in the subsequent checklist ( Lobban et al. (2012). The Chuuk specimens can be identified as this species also, given that the areolae were not visible in LM. Ruck et al. (2016) proposed the transfer of all Rhopalodia to (or back to) Epithemia , and made several formal transfers, but not including the two Krammer taxa considered here. R. gibberula , from which those two new species were disambiguated, was Epithemia gibberula . We formally propose the nomenclatural changes below.

Figures

FIGURES 168–180. Seven diatoms species of Rhopalodiales and Surirellales.Figs 168 and 169. Plagiodiscus nervatus. Fig.170. Coronia decora. Figs 171–173. Epithemia. guettingeri. Fig. 174. Campylodiscus brightwellii. Fig. 175. Campylodiscus fastuosus. Fig. 176. C. scalaris. Figs 177–180. C. neofastuosus. Scale bar = 10 μm.