Ancyromonas sigmoides Kent, 1880

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 : 548

Ancyromonas sigmoides Kent, 1880 (fi gures 21r -t, 24a, b)

Description. Gliding fl agellate, cell outline oval, 3-7 Mm long (mostly 3-5 Mm) and 2-3.5 Mm wide, dorso-ventrally fl attened. This species has a shallow groove ventrally near an antero-lateral margin of the cell. Cells may or may not have a thin stiff anterior fl agellum emerging from an anterior depression. The anterior fl agellum can be easily overlooked. The posterior fl agellum is about 1.5 times the length of the cell and may not be acronematic. Moves by gliding with the posterior fl agellum trailing. Common. Description based on observations of 31 cells.

Remarks. Previously reported lengths range from 2 to 7.6 Mm. This species has been reported from marine sites in Antarctica, Australia, Arctic Canada, Denmark, Fiji, Gulf of Finland, Greenland, Hawaii and Panama ( Larsen and Patterson, 1990; Vørs, 1992a, 1992b; Ekebom et al., 1996; Tong, 1997a; Tong et al., 1997, 1998; Bernard et al., 1999). Our observations are in agreement with the observations of previous authors. Ancyromonas sigmoides can be confused with Metopion ¯uens, but is distinguished by the anteriorly directed fl agellum; the second fl agellum in M. ¯uens is thicker and is directed to the rear. It is similar to A. melba Patterson and Simpson, 1996 , found in hypersaline habitats of Shark Bay, subtropical Australia, but A. melba has an anterior fl agellum which is as thick as the posterior fl agellum, and the cell is slightly larger. We observed one cell having an anterior fl agellum which was basally thickened (fi gure 21t).