Krammer 2002 Category: Asymmetrical biraphid
BASIONYM: Cymbella tropica Krammer 2002
Contributor: Marina Potapova - February 2011
Length Range: 26-42 µm
Width Range: 8.5-12 µm
Striae in 10 µm: 9-10 in center valve, 13-14 at apices
Valves are moderately dorsi-ventral, with slightly protracted apices. The dorsal margin is strongly arched, whereas the ventral margin is slightly convex. The central area is small, elliptical. A single elongated stigma is present at the end of the middle striae. Rarely in larger valves there may be two stigmata. The proximal raphe ends have central pores that curve to the ventral margin. The raphe is lateral, becoming filiform near the distal end. Striae are radiate. The areolae are apically elongated, they number 22-25 in 10 μm.
Basionym: Cymbella tropica
Author: Krammer 2002
Length Range: µm
Striae in 10 µm:
Cymbella tropica nov. spec. [Figs 44: 1-10]
Cymbella turgidula sensu Metzeltin & Lange-Bertalot 1998, figs 133: 14-16
Type locality: Venezuela, Rio Manizanes, leg. Rumrich 4.4.90. slide 1015D IOK.
Valves slightly dorsiventral, broadly-lanceolate, dorsal margin strongly arched, ventral margin moderately convex. Ends not protracted or slightly subrostrate and bluntly rounded. Length 35-44 μm, breadth 10-12 μm, maximal length/breadth ratio 4. Axial area narrow, linear, broadening slightly into a very small rounded or indistinct central area. Raphe not ventrally displaced, distinctly lateral, becoming filiform near the distal ends and slightly reverse-lateral just at the proximal ends. Proximal raphe ends slightly rounded; terminal fissures indistinct but, when noted, dorsally deflected. Striae slightly radiate from the middle to the ends, punctate. One large isolated stigma just at the end of the middle stria on the ventral side, in larger specimens sometimes two. Striae in the middle portion 9-11/10 μm (dorsal and ventral), becoming 12/10 μm towards the ends, puncta 21-24/10 μm (var. 25- 28/10 μm).
Krammer, K. (2002). The genus Cymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 3: 1-584.
NADED ID: 23817