Heterochromonas opaca Skuja, 1948

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 : 551

Heterochromonas opaca Skuja, 1948

(fi gures 24i, 25n -p)

Description. Cell outline oval, about 18 Mm long and 11 Mm wide, somewhat dorso-ventrally fl attened, rigid, with an anterior protrusion and a central nucleus. Cells have a deep ventral depression and are somewhat warty. Two fl agella insert subapically into the depression; the anterior fl agellum is about 0.5 times the cell length, and the posterior fl agellum is slightly longer than the cell and inserts below the anterior fl agellum. Moves by gliding with the anterior fl agellum directed forwards and the posterior fl agellum trailing. Three cells observed.

Remarks. The organisms observed are very similar to Heterochromonas opaca Skuja, 1948 in cell length and the position of nucleus, in having two fl agella which differ in length, and having a ventral depression and the anterior protrusion. In the original description of Skuja (1948) the anterior fl agellum is longer than the posterior fl agellum. Heteronema opaca is similar to Diplonema papillatum ( Porter, 1973) Triemer and Ott, 1990 in general appearance and cell length, but it can be distinguished because D. papillatum is fl exible. Also, H. opaca resembles Abollifer prolabens Vørs, 1992 ; A. prolabens has one fl agellum, but sometimes the second shorter fl agellum may appear before cell division (Vørs, 1992a). Heterochromonas opaca resembles Cruzella marina (see de Faria et al., 1922), but can be distinguished because C. marina is fl exible and has a long anterior fl agellum. It is distinguished from other species of Heterochromonas by the anterior protrusion. This genus includes about 13 species; Heterochromonas bodoides Skuja, 1948 , H. chlorophaga Skuja, 1956 , H. cryptostigma Skuja, 1939 , H. globosa Skuja, 1948 , H. gotlandica Skuja, 1956 , H. hovassei Fiatte and Joyon, 1965 , H. nobilis Skuja, 1956 , H. ovaca Skuja, 1948 , H. polysticta Skuja, 1948 , H. rotundata Skuja, 1956 , H. spaerophora Skuja, 1956 , H. vivipara (Ehrenberg, 1838) Pascher, 1912 and H. vulgaris (Cienkowsky, 1870) Pascher, 1912 (see Pascher, 1912; Skuja 1939, 1948, 1956).