Gomphonema pantropicum Reichardt 2015

Glushchenko, Anton, Kulikovskiy, Maxim & Kociolek, John Patrick, 2017, New diatom species from the Gomphonema subtile group in Southeast Asia, Phytotaxa 329 (3), pp. 223-232 : 225

Gomphonema pantropicum Reichardt 2015 ( Figs 1–33 )

Synonym. Gomphonema subtile var. malayense Hustedt 1942 .

Remarks. Specimens in our samples were 33–59 μm long, 6.5–8.5 μm wide, and had 9–12 striae in 10 μm. The shape of the apices in our studied populations are more variable than it was shown by Reichardt (2015). Reichardt (2015) concluded that G. pantropicum has capitate apices while specimens in our studied populations have slightly rostrate to capitate apices. It is possible that we have shown larger morphological variation for this species.

This species was found in samples 00323, 01090, 02143, 02144, 02269, 02355, 03817, 04599.

Figures

FIGURES 1–25: Gomphonema pantropicum Reichardt. LM. Size diminution series, valve views. Scale bar = 10 μm.

FIGURES 26–33: Gomphonema pantropicum Reichardt.SEM.Figs 26, 28, 30, 32 are external views; 27, 29, 31, 33 are internal views.Fig. 26. Whole valve illustrating valve shape, with characteristic headpole and footpole. Fig. 27. Whole valve, showing small pseudoseptum at each pole, and prominent central nodule. Fig. 28. Valve center with slightly dilated proximal raphe ends, small, round stigma opening and areolae occluded by flaps. Fig. 29. Valve center with undulate central nodule bearing bent proximal raphe ends and ovoid stigma opening. The striae occur in trough-like structures. Fig. 30. Headpole, with the hooked-shaped distal raphe end curving onto the valve mantle. Occluded areolae are evident. Fig. 31. Headpole, showing prominent helictoglossa and pseudoseptum. Fig. 32. Footpole, with round porelli physically separated and morphologically distinct from the areolae. Fig. 33. Footpole, with large helictoglossa and pseudoseptum evident. Scale bars = 5 μm (Figs 26, 27); 1 μm (Figs 28–33).