Mastogloia cf. pumila (Grunow) Cleve Figs 68–72

Section Sulcatae

Ref. illus.: Hustedt 1931 –1959, fig. 983; Witkowski et al. 2000, pl. 83, figs 5, 6; Loir & Novarino 2013, pl. 19c

Sample: GU52P-1, GU52P-9

Dimensions: Length 10–17 µm, width 5.5–6.5 µm; striae 27 in 10 µm, radiate

Diagnostics: Small valves, elliptical-lanceolate with slightly rostrate apices; central area extended into an H-shaped hyaline area. In our small cells, 1–2 large partecta in the middle flanked by 1–2 tapering partecta on each side and the H-shaped hyaline area is not evident externally.

Comments: These small specimens have chambers much like M. sergiana Pennesi & Poulin (Lobban et al. 2012, pl. 36, figs 7, 8 and pl. 37 figs 1, 2), M. manokwariensis Cholnoky (Lobban et al. 2012, pl. 32, figs 1–3), M. pusilla var. subcapitata Hustedt (Hustedt 1931 –1959, fig 1002e, Loir & Novarino 2013, pl. 20b), and M. urveae Witkowski, Lange-Bertalot & Metzeltin (Witkowski et al. 2000, pl. 84, figs 22, 23, Loir & Novarino 2013, pl. 24a, 27b). However, the elliptical valve outline and the distinct lyrate hyaline area distinguish it from each of these. M. urveae also differs in having parallel striae (Witkowski et al. 2000). Larger size ranges for M. pumilla were given by Hustedt (1931 –1959) (20–20 x 5–9 µm) and Loir & Novarino (2013) (17.5–25 x 6.5–7.5 µm).