Diploneis sp. 4

Jovanovska, Elena, Levkov, Zlatko & Edlund, Mark B., 2015, The genus Diploneis Ehrenberg ex Cleve (Bacillariophyta) from Lake Hövsgöl, Mongolia, Phytotaxa 217 (3), pp. 201-248 : 241-242

Diploneis sp. 4 ( Fig. 271 )

The valve is linear-elliptical with convex margins and round ends. The valve length is 14.0 μm, and the valve breadth is 5.5 μm. The axial area is very narrow, linear to lanceolate, expanding towards the round central area. The central area is ca. 1.0 μm wide. The longitudinal canal is very narrow, linear to lanceolate, expanded in the middle of the valve, with one row of areolae throughout the whole length. The raphe is straight with expanded proximal ends. Striae are parallel in the middle of the valve, quickly becoming radiate, 23 in 10 μm. Areolae not discernable with LM observations.

Observations: —The morphological features, such as valve outline, valve size, and structure of the longitudinal canal make Diploneis sp. 4 morphologically closely related to D. separanda and D. fontanella . More valves are necessary to make detailed comparisons and full description of Diploneis sp. 4 .

Ecology and Distribution: —M167A: found only in a peat collection submerged in a small stream in Arkhangai province. Not encountered in Lake Hövsgöl.

Figures

FIGURES 253–271. LM and SEM external valve views. Fig. 253. Diploneis cf. eximia, LM valve view. Figs 254, 255. Diploneis cf. minuta, SEM external valve views. Fig. 254. Valve view. Fig. 255. Proximal raphe endings. Figs 256–259. Diploneis sp. 1. Fig. 256. LM valve view. Fig. 257. Central area with proximal raphe endings, SEM. Fig. 258. Distal raphe endings, SEM. Fig. 259. View of the entire valve, SEM. Figs 260–269.Diploneis sp. 2, LM valve views. Fig. 270. Diploneis sp. 3, LM valve view.Fig. 271. Diploneis sp. 3, LM valve view. Scale bars = 10 μm (Figs 253, 256, 260–271); 5 μm (Figs 254, 259); 2 μm (Figs 255, 257, 258).