Plagiogramma atomus Greville, 1863

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

Plagiogramma atomus Greville Fig. 106

Ref. illus.: Ricard 1977 pl. 10, fig. 10; Witkowski et al. pl. 3, figs 7, 8; Hein et al. 2008, pl. 4, figs 9,10

Samples: GU44L-E

Dimensions: Length 25–28 µm, width 13–14 µm; striae ca. 11 in 10 µm

Diagnostics: The bilobed outline together with the dimensions define this species.

Comments: Larger and more finely areolate than a more common, so far unidentified specimens close to P. bilobatum . Reported for Guam by Arai (2010, pl. 8, fig. 2).

Figures

Figures 98–106. Figs 98–105. Pinnunavis yarrensis (GU69A-1). Fig. 98. Live cell showing plastid lobes below the valve surface (DIC). Figs 99–101. Three valves of different sizes (DIC). Fig. 102. Detail of areolae and central area, external (SEM). Fig. 103. Detail of girdle view showing valvocopula with single row of pores (SEM). Fig. 104. Fragment of apex, broken along the raphe slit, showing helictoglossa and thickened interstriae (SEM). Fig. Detail of valvocopula showing fluted margin of the pars interior (SEM). Fig. 106. Plagiogramma atomus, external valve view (GU44L-E) (SEM). Scale bars: Fig 98–101 = 10 µm, Figs 102–106 = 5 µm.