Mastogloia ovata Grunow, 1860

Lobban, Christopher S. & Witkowski, Andrzej, 2023, Marine benthic diatoms of Guam: new records, Dictyoneis apapae sp. nov., and updates to the checklist, Micronesica 2023 (2), pp. 1-75 : 10

Mastogloia ovata Grunow Figs 65, 66

Ref. illus.: Hustedt 1931 –1959, p. 476, fig. 895

Lobban et al. 2012, p. 281, pl. 35, figs 1, 2 (as “ M. pseudolatecostata ”)

Lobban et al. 2012, p. 279, pl. 33, figs 7, 8 (as “ M. ovata ”)

Samples: GU44T-1, GU44 AJ, GU44AU-1; GU52P-7; GU70A-2A

Our specimen published as voucher for M. pseudolatecostata must be rejected because the stria density is too high (21–24 vs 12–14 in 10 µm). It is a better match for M. ovata than the voucher specimen cited in the same paper. SEM images of such specimens are shown in Figs 65, 66. A specimen from Bikar Atoll, Marshall Islands that matches M. pseudolatecostata is shown in Fig 67; this species not yet identified in Guam. The specimen claimed as a voucher for M. ovata in Lobban et al. 2012 less clearly matches the description in Hustedt (1931 –1959) and close to Hein et al. (2008, pl. 40, fig. 3) “ Mastogloia cf. ovata . ”

Comments: The inner margin of M. ovata has indentations at each cross wall ( Fig. 66), that of M. pseudolatecostata in the middle of each partectum ( Fig. 67).