Acronema debruynei, De Saedeleer, 1931

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 : 540-541

Amastigomonas debruynei De Saedeleer, 1931

(fi gures 21i, 22a)

Description. Cell 5-6 Mm long, dorso-ventrally fl attened, fl exible but not amoeboid. The anterior fl agellum emerges from the tip of a laterally directed sleeve, the posterior fl agellum trails under the cell and occasionally protrudes behind the cell; strands of cytoplasm may be drawn out behind the cell. The nucleus is situated in the anterior left of the cell. Rarely observed.

Remarks. Amastigomonas is a senior synonym of Thecamonas . Amastigomonas debruynei is the same as organisms described as T. trahens , A. borokensis and A. caudata ( Ekebom et al., 1996) . Previously reported lengths are 3-7.5 Mm. Amastigomonas debruynei was previously recorded from marine sites in subtropical and tropical Australia, North Atlantic, Brazil, Arctic Canada, Denmark, England, Gulf of Finland, Greenland, Hawaii and Panama ( Larsen and Patterson, 1990; Vørs 1992a, 1992b, 1993a, 1993b; Patterson et al., 1993; Ekebom et al., 1996; Tong, 1997 a, 1997b; Tong et al., 1998). Other species in the genus include A. bermudensis , A. ®losa and A. mutabilis . This species can be distinguished from A. bermudensis Molina and Nerad, 1991 by its smaller size ( A. bermudensis , 8-11.5 Mm), and from A. mutabilis by its smaller size ( A. mutabilis measures up to 15 Mm) and the lack of granules located ventrally adjacent to the posterior fl agellum. It is distinguished from A. ®losa because it lacks the thin cytoplasmic extensions which are distinctive for A. ®losa.

Amastigomonas mutabilis ( Griessmann, 1913) Molina and Nerad, 1991 (fi gures 21j, k, 22b)

Description. Cell elliptical, 11-16 Mm long, dorso-ventrally fl attened, fl exible. With a fl exible sleeve around the base of the anterior fl agellum. The anterior fl agellum is about 0.5 times the length of the cell and is the same thickness as the posterior fl agellum. The recurrent posterior fl agellum is slightly longer than the cell and trails under the body, to which it attaches loosely in a slight groove. The nucleus is situated subapically near the right margin of the cell. Some cells have granules alongside the recurrent fl agellum. Relatively rare.

Remarks. This species was fi rst described as Rhynchomonas mutabilis by Griessmann (1913), transferred to Thecamonas by Larsen and Patterson (1990) and to Amastigomonas by Molina and Nerad (1991). Previously reported length ranges are 7-15Mm. It has been described from marine sites in subtropical Australia, Brazil, Denmark, England, France, Greenland and North Atlantic ( Griessmann, 1913; Ruinen, 1938; Larsen and Patterson, 1990; Vørs, 1992b, 1993a; Patterson et al., 1993; Patterson and Simpson, 1996; Tong, 1997b; Tong et al., 1998;). Some cells lack the rows of granules which follow the line of the posterior fl agellum and were suggested to be distinctive by Larsen and Patterson (1990). Amastigomonas mutabilis is distinguished from A. debruynei by its larger size and the presence of granules alongside the posterior fl agellum, and by its longer anterior fl agellum. This species resembles A. bermudensi s Molina and Nerad, 1991 at 8.0-11.5 Mm in general appearance and their size ranges overlap. Amastigomonas bermudensis may be a synonym of A. mutabilis . Further work is required to clarify the identities of species in this genus.