Pogoneis bahrainii F.E. Round & P.W. Basson

Lobban, Christopher S., 2015, Benthic marine diatom flora of Guam: new records, redescription of Psammodictyon pustulatum n. comb., n. stat., and three new species (Colliculoamphora gabgabensis, Lauderia excentrica, and Rhoiconeis pagoensis), Micronesica 2015 (2), pp. 1-49 : 11-12

Pogoneis bahrainii F.E. Round & P.W. Basson Figs 107–113

ORDER and Family incertae sedis

Ref. illus.: Round & Basson 1997, figs 1–3, 13–25

Samples: GU44I-4

Dimensions: 15–17 µm long, 2.3–2.7 µm wide; striae 45 in 10 µm (both valves).

Diagnostics: The monoraphid frustules are very distinctively shaped like a canoe in girdle view because of thickenings on raphe valve ( RV) apices and the curvature of the sternum valve (SV). Striae are parallel and comprise slits which are apically elongated on both valves, except diagonal near RV apices.

Comments: Dimensions and stria densities agree with Round & Basson’s material from Bahrain. A slide from this sample with the holotype of Cyclophora minor (accession #627405, slide 223019) at California Academy of Sciences also has a marked specimen of P. bahrainii . The taxonomic position of this genus was not specified by Round & Basson (1997); as a monoraphid diatom it could have been placed in Achnanthales , but since Cox (2006) removed Achnanthes sensu stricto to Mastogloiales , there is no single order to which all monoraphid taxa belong.

Figures

Figures 107–113. Pogoneis bahrainii. (GU44I-4) (SEM, except Fig. 107 DIC). Fig 107. Frustules in valve and girdle views. Fig. 108. Frustule in girdle view. Fig 109. SV, external view. Fig. 110. Detail of central area of RV. Fig. 111. Detail of apex of RV, showing the thickened “prow.” Fig. 112. RV, internal view showing silica plate bordering the raphe and extending into interstrial costae. Fig 113. RV, detail of internal view showing apex. Scale bars: 107 = 10 µm; 108–113 = 1 µm.