Cocconeis sp. 1

(Figs. 106-109)

Valves elliptic, ends rounded. Valve with raphe: axial area linear and narrow, central area narrow, raphe filiform. Striae delicate interrupted by submarginal hyaline line. Valve without raphe: axial area linear and narrow. Striae slightly radiate. Areolae inconspicuous. Length: 9-11 μm; width: 5.5-6.0 μm; striae 24-26 in 10 μm in both valves. This taxon differs from other Cocconeis Ehrenberg species by the very small dimensions and the presence of delicate striae, hardly visible in LM.

Material examined: BRAZIL, MATO GROSSO DO SUL: Batayporã, Garças Lake, 21.IX.2017, sediment, D.T. Ruwer (Nupélia UEM - 18085-18097) .