Petalomonas virgatus Lee and Patterson, 2000

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 : 525-526

Petalomonas virgatus Lee and Patterson , n. sp.

(fi gures 14l, 15j -l. Type micrograph: fi gure 15j)

Diagnosis. Petalomonas , cell oval, about 7 Mm long and 4 Mm wide, not fl attened. With one emergent thickened fl agellum and numerous longitudinal ridges on both faces of the cell.

Description. Colourless, cell outline oval, about 7 Mm long, 4 Mm wide, not fl attened. Cell outline is circular in cross section. The cell has prominent longitudinal ridges on both sides of the cell and has one thickened fl agellum, which is about 1.5 times the cell length and emerges from a reservoir situated in the right-hand side of the cell. Moves slowly by gliding. One cell observed from Botany Bay; the description also includes information on cells observed by Ekebom and co-workers on the Great Barrier Reef but excluded from Ekebom et al. (1996) because too few cells had been observed.

Remarks. This species is assignable to Petalomonas because it is a heterotrophic euglenid with a rigid body, one emergent fl agellum, and subapical canal opening. It is not fl attened, unlike most Petalomonas species. The ridges in P. virgatus resemble rod-shaped epibiotic bacteria such as those in Postgaardi mariagerensis Fenchel et al., 1995 ( Simpson et al., 1997b). Petalomonas virgatus is easily distinguished from all other small gliding species by its ridges. It was found at One Tree Island in tropical Australia by Ekebom and co-workers but not reported. This species is very similar to Calycimonas Christen, 1959 which also has one emergent fl agellum, and differs from Petalomonas by not being fl attened ( Christen, 1959). We do not regard this criterion as an effective taxonomic distinction and consider Calycimonas to be a junior synonym of Petalomonas . Calycimonas was created by Christen (1959) to segregate some species from the genus Petalomonas because he was of the view that it was becoming too big. Calycimonas contains four species; C. physaloides Christen, 1959 , C. pusilla Christen, 1962 , C. quinquecarinata Christen, 1962 , C. robusta Christen, 1962 (see Christen, 1959, 1962a). They may be transferred to Petalomonas to create the new combinations; P. physaloides n. comb., P. christeni nom. nov., P. quinquecarinat a n. comb. and P. calycimonoides nom. nov. As Petalomonas pusilla and P. robusta were introduced by Klebs ( Klebs, 1893) (see P. poosilla above) and Christen ( Christen, 1962b) respectively, the transfer of C. pusilla and C. robusta to Petalomonas creates homonyms. We therefore introduce P. christeni as a nom. nov. for Calycimonas pusilla and Petalomonas calycimonoides as a nom. nov. for C. robusta .