Mastogloia affirmata (Leuduger-Fortmorel) Cleve, 1892

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 : 6-7

Mastogloia affirmata (Leuduger-Fortmorel) Cleve Figs 49, 50

Section: Undulatae

Ref. illus.: Hustedt 1931 –1959, fig. 962.

Samples: GU44AX-1

Dimensions: Length 39 µm; width 22 µm; transapical striae 14 in 10 µm, longitudinal striae 10 in 10 µm except for the wider row adjacent to axial area; partecta 3.3 µm wide, 13 in 10 µm.

Diagnostics: Coarsely areolate, those along the raphe notably elongated; apices produced; longitudinal ribs almost straight; partectae very narrowly rectangular.

Comments: Distinguished from the very similar M. bahamensis Cleve ( Hustedt 1931 –1957, fig 963, Hein et al. 2008, pl. 34, fig. 6 and pl. 36, fig. 10), which has irregularly wavy longitudinal ribs, according to Hustedt, and from M. subaffirmata Hustedt (see below) by the much coarser striae. Record based on a single specimen from Guam, but also seen in samples from Yap (unpublished).

Figures

Figures 41–50. Figs 41, 42. Hemidiscus cuneiformis var. ventricosa (GU66F-4) (DIC). Fig. 41. Valve view; arrow points to pseudonodulus. Fig. 42. Oblique view with focus on several of the rimoportulae (arrow). Figs 43–48. Lauderia excentrica. Fig. 43. Holotype specimen (GU44I-1) (DIC). Fig. 44. External view of valve showing excentric, reniform annulus and external rimoportula opening (arrow) (GU44Y-13) (SEM). Fig. 45. External detail of annulus (GU55B-4) (SEM). Fig. 46. Internal view of valve with rimoportula (arrow), also showing the external aspect of the fultoportulae along the bottom rim (GY44Y-13) (SEM). Figs 47, 48. External and internal details of striae and fultoportulae, showing 5 satellite pores in the central fultoportulae (arrowhead) and 2-4 in the striae (arrow) (GU44Y-13) (SEM). Figs 49, 50. Mastogloia affirmata valve and valvocopula at two focal planes (GU44AX-1) (DIC). Scale bars: Figs 41, 42, 49, 50 = 10 µm, Figs 43, 44, 46 = 5 µm, Figs 45, 47, 48 = 2 µm.