Amphora spectabilis Gregory, 1857

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 : 3

Amphora spectabilis Gregory Figs 3, 4

Ref. illus.: Levkov 2009, p. 265, pl. 114, figs 1–5, pl. 252, figs 1–5 ( SEM).

Samples: GU55B-5

Dimensions: Length 30 µm, width 12 µm, stria density 8 in 10 µm (dorsal) and 13 in 10 µm (ventral)

Diagnostics: More strongly and coarsely striated on the dorsal surface, dorsal striae often biseriate and bifurcating towards the sternum, ventral striae uniseriate.

Comment: Our specimens (seen also in Yap and Palau) are much shorter than the 68–129 µm given by Levkov (2009). A Palauan specimen ( Fig. 4 ) seen in SEM shows that the striae are mostly biseriate, the bifurcations resulting from the two rows diverging; these images conform to the specimens shown by Levkov in SEM.

Figures

Figures 1–7. Figs 1, 2. Actinocyclus cuneiformis, LM, arrows showing rimoportulae. Figs 3, 4. Amphora spectabilis: Fig. 3. LM at two focal planes showing different striae densities on dorsal and ventral surfaces. Fig. 4. Palau specimen in SEM showing character of striae. Figs. 5–7. Amphora subhyalina. Fig. 5 LM, showing the hyaline character. Fig. 6. SEM detail of valves with conopea at central raphe endings (arrow), also showing striae on dorsal (double arrowhead) and ventral (single arrowhead) part of girdle band. Fig. 7. Frustule showing broad dorsal part of some girdle bands. Scale bars: Figs 1–5, 7 = 10 µm, Fig. 6 = 5 µm. Unless indicated otherwise, all light microscopy (LM) was with differential interference contrast (DIC).