Staurastrum leptocladum var. cornutum Wille

Staurastrum leptocladum var. cornutum Wille *

( Fig. 7A View FIG )

Bihang till Kongliga Svenska Vetenskaps-Akademiens Handlingar 8 (18): 19 ( Wille 1884).

DISTRIBUTION. — Cosmopolitan. Amazon Basin: Förster (1969); Thomasson (1971); Uherkovich & Schmidt (1974); Uherkovich (1976, 1981); Sophia & Huszar (1996); Melo et al. (2005); Cadima (2013). Western Amazonia (lowlands): no records.

DESCRIPTION

Cells 34.0-36.0 µm long, 85.1-104.9 µm wide with processes; isthmus: 7.5-9.5 µm. Cells are characterized by their apices with two horns arranged in a divergent way. Cells with shallow median constriction, reduced median sinus; smooth cell wall. The ornamentation on the base of the semicells is variable; subtriangular semicells, lateral angles prolonged in long processes, margins irregularly wavy, and always more or less curved upwards.

REMARKS

The size and morphology of our specimens coincided with those reported by Förster (1969) for the Brazilian Amazon and Tell (1980) for Northern Argentina. This taxon was the one with the higher occurrence among all our sampling sites (it appeared in six out of eight sites) and presented a variable range in cells size, which is fairly common for this taxon ( Tell 1980).