Mastogloia matthaei Pennesi & Poulin Figs 58–61

Section: Ellipticae

Ref. illus.: Pennesi et al. 2013, figs 37–44, 53–56

Samples: GU52P-2

Dimensions: Length 14–15 µm; width 9 µm; striae 24–27 in 10 µm.

Diagnostics: Small oval valves with 3 concave/bilobed partecta on each side, reaching the apex. Quadrangular areolae in irregular longitudinal striae; internal areolae in longitudinal rows (not seen yet in Guam specimens).

Comments: Very similar to M. ovulum Hustedt, M. emarginata Hustedt and M. stellae Pennesi & Poulin in size and shape of the valve and the bilobed partecta. Differs in the shape and arrangement of the areolae from M. ovulum (Figs 56, 57), which has apically elongate areolae tending to form an irregular quincunx pattern and internal areolae not in longitudinal rows (Pennesi et al. 2013, table 1). Distinguished from M. emarginata (see above) in lacking the evident partectal pores and from M. stellae in the striae pattern and shape of the areolae (rectangular and sunken in contrast to round and flush).