Diploneidaceaea Mann

Al-Handal, Adil Y., Compère, Pierre & Criobe-Usr, Catherine Riaux-Gobin, 2016, Marine benthic diatoms in the coral reefs of Reunion and Rodrigues Islands, West Indian Ocean, Micronesica 2016 (3), pp. 1-78 : 26

Family Diploneidaceaea Mann

Diploneis crabro Ehrenberg (Pl. 8, Fig. 11) References: Hustedt 1931 -59, p. 616, fig. 1028; Witkowski et al. 2000, p. 184, pl. 93, figs 18-21; Lobban et al. 2012, pl. 44, fig. 5; pl. 45, figs 1, 2.

Features: Apical axis: 52-86 µm, transapical axis: 18-24 µm, striae 6-8 in 10 µm. Valves panduriform with abruptly round to acute apices. Central raphe endings sub-orbicular and extended to form parallel horns. Furrows relatively narrow and bordered by large areolae. Costae coarse and alternating with double rows of areolae.

Remarks: specimens from the Mascarenes are smaller in size with higher stria density than those reported from other geographical regions (see ref. cit.). Widely distributed marine species. Occurrence: Rare in Reunion Island. Previously reported from Seychelles (G).

Diploneis smithii (Brébisson) Cleve (Pl. 8, Fig. 12) References: Hustedt 1931 -59, fig. 1051; Witkowski et al. 2000, pl. 88, figs 2-5, pl. 89, fig. 1; Lobban et al. 2012, p. 290, pl. 45, figs 3–6; pl. 46, fig. 1.

Features: Apical axis: 30-58 µm, transapical axis: 14-30 µm, striae 12-16 in 10 µm. Valves elliptical with round apices. Central raphe endings small, round or elliptical with truncate ends, expanded forming two horns on both sides of the raphe. Furrows narrow and close to the horns. Costae separated by two rows of areolae decreasing in size towards valve margins.

Remarks: Taxon variable in valve shape, outline and length of longitudinal canals which run across valve width. Several varieties were described but these may be variations due to different environmental conditions ( Droop 1994, Lobban et al. 2012,). Widely distributed species in marine, brackish and inland waters with high conductivity.

Occurrence: Frequent in Reunion and Rodrigues Islands. Previously reported from Seychelles (G).