Micrasterias furcata var. dichotoma (Wolle) Růžička

Micrasterias furcata var. dichotoma (Wolle) Růžička **

( Fig. 4E View FIG )

Die Desmidiaceen Mitteleuropas 1 (2): 383 ( Růžička 1981). — Micrasterias dichotoma Wolle , Bulletin of the Torrey Botanical Club 11: 14 ( Wolle 1884a). — Micrasterias radiata var. dichotoma (Wolle) J. A. Cushman, Rhodora 10 (114): 108 ( Cushman 1908).

DISTRIBUTION. — Europe, North and South America. Amazon Basin: no records. Western Amazonia (lowlands): no records.

DESCRIPTION

Cells 181.5-194.2 µm long, 184.0-192.5 µm wide, isthmus 19.7-22.1 µm, apex 70-83.2 µm; cells are as long as wide. Cells with a deep median constriction, median sinus open with acute angles; finely punctuated cell wall. Semicircular semicells, five-lobed, apical lobe slender, and narrowing towards the apex; apical margin slightly concave in the middle region, ends forming two processes elongated, divergent, two-denticulated; lateral and basal lobes forming approximately V-shape incisions; lateral lobes slender, similar to each other, divided into two-denticulated lobules.

REMARKS

Compared with the type variety, this taxon is larger in size, more circular in shape, polar and lateral lobes are slender, incisions among lobes are deeper, polar lobe with concavity more open, but not as open as in M. radiata var. dichotoma presented in Krieger (1939). Our measurements coincided with those shown by Krieger (1939) yet bigger than those shown in Santos et al. (2016).