Diploneis potapovae

Valves of smallest stages simply elliptical, all larger ones are linear-elliptical to linear; ends broadly rounded. Length 14–30 μm, breadth 8–12 μm; ratio length- to-breadth 1.8–3. Raphe filiform, straight or both branches slightly oblique to each other; proximal ends barely expanded, distal ends shortly deflected. Axial area very narrow, about 1 μm wide, weakly expanding from the poles towards the centre. Central area more or less set off, only 1.5–2 μm wide, i.e. 1/5th or less of the valve width. Canal system about 1/4th of the valve width proximally, there arcuate around the central nodule. Striae weakly radiate or subparallel proximally, becoming gradually more strongly radiate near the ends, 15–16 in 10 μm. Areolae clearly uniseriate on almost the entire valve face but becoming opposedly biseriate close to the margins (when appropriately focussing), 20–21 in 10 μm. Canal areolae parallel to the axial area, uniseriate on either side and strongly contrasted. Flanking internal depressions are not recognisable.

SEM external view see Figs 89: 1–4. Proximal raphe ends shortly bent; distal raphe ends moderately longer curved. Cribra, virgae and vimines forming a prominent relief on the valve surface. The comparatively large cribra—each one consisting of a large number of poroids—appear uniseriate throughout at first glance, just as in LM view. Closer inspection shows them to become opposedly biseriate, often incompletely so, towards the mantle. In the middle of each paired marginal cribrum we find a circle of rather wide poroids, as is the case in D. boldtiana and several other Diploneis species. SEM internal view see Fig. 88: 33.

• Author
  Lange-Bertalot, Fuhrmann and Cantonati 2020
• Length Range
  14–30 µm
• Width
  8–12 µm
• Striae in 10µm
  15-16