Sphenomonas angusta Skuja, 1956

Lee, Won Je & Patterson, David J., 2000, Heterotrophic flagellates (Protista) from marine sediments of Botany Bay, Australia, Journal of Natural History 34, pp. 483-562 : 532

Sphenomonas angusta Skuja, 1956

(fi gures 19f -h, 20a)

Description. Cell measuring 10-14 Mm long, 4-5 Mm wide, not fl attened, with a dorsal groove. Cells are anteriorly obliquely truncated, posteriorly rounded. The cell bodies are slightly curved: the right margin of the cell is straighter than the left one. With two fl agella, unequal in length, emerging from a relatively large fl agellar pocket located in the right anterior end of the cell. The anterior fl agellum is about 1.5 times the cell length and its proximal part moves actively; the trailing posterior fl agellum is less than 0.5 times the cell length. One large refractile inclusion often occupies the posterior part of the cell. Commonly observed.

Remarks. This species was fi rst described from freshwater sites by Skuja (1956). Cells described here are below the length range 13-21 Mm of Skuja (1956), but generally our observations are in accordance with his original description. Most species of the genus Sphenomonas have been found in freshwater sites, but we have commonly observed only one species, S. angusta , and seen it in all seasons. At times this species occurs in large numbers. Sphenomonas elongata Lackey, 1962 was found in marine sites and differs from S. angusta in its larger size (40-70 Mm). Sphenomonas angusta is distinguished from other species of the genus by having one dorsal groove.