Petalomonas raiula Larsen and Patterson, 1990

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 : 524-525

Petalomonas raiula Larsen and Patterson, 1990

(fi gures 14i, 16k, l)

Description. Cell outline irregular, 15-20 Mm long, 10-15 Mm, with a ventral groove with raised margins which extend from the collar around the fl agella canal. The organism has thin lateral hyaline fl anges; the left one extends anteriorly to form an arc around the fl agellum and the right one ends behind this arc. It has a wedgeshaped posterior end with, in most cells, a hyaline protrusion and lateral margins. There is one emergent fl agellum, which is about as long as the cell and is anteriorly directed. The reservoir is situated anteriorly in the right side of the cell and the nucleus is near the midline of the left-hand side. Sometimes commonly oberserved.

Remarks. Larsen and Patterson (1990) fi rst described this species from marine sites in Brazil and Fiji, and the organism was found in subtropical Australia by Patterson and Simpson (1996). Previously reported cell length ranges 9-19 Mm ( Larsen and Patterson, 1990; Patterson and Simpson, 1996). Generally, the organisms described here are in accordance with observations of previous observers although we increase the known maximal size to 20 Mm. Petalomonas raiula is usually distinguished from other small species of the genus Petalomonas by its posterior protrusions and ridged ventral groove. Petalomona s dentata Christen, 1962, P. irregularis Skuja, 1948 , P. lata Christen, 1962 , P. praegnans Skuja, 1948 , P. phacoides Skuja, 1931 , P. platyrhyncha Skuja, 1948 , P. mira Awerinzew, 1907 , P. mira var. appendiculata Skuja, 1939 , P. mira var. bicarinata Skuja, 1939 , P. sinuata Stein, 1878 , P. spinifera ( Lackey, 1962) Lee and Patterson , n. comb., P. steinii Klebs, 1893 and P. tricarinata Skuja, 1939 also have posterior protrusions but with different patterns ( Huber-Pestalozzi, 1955; Christen, 1962b; Lackey, 1962). This species is a member of a group of Petalomonas species having one ridged ventral groove; the group also includes P. abscissa , P. mira and P. triquetrus .

Petalomonas spinifera ( Lackey, 1962) Lee and Patterson , n. comb. (fi gures 14j, 16m, n)

Description. Cell outline irregular, about 29 Mm long and 21 Mm wide, fl attened, with three fi ne dorsal ridges and one distinct ridged ventral groove which extends from the collar around the fl agella canal. The cell has four hyaline protrusions: one is located on a wedge-shaped posterior end of the cell, two are in the lateral posterior part, and the last one is in the anterior left-hand side or near the nucleus. One emergent fl agellum, which is slightly shorter than the cell, is anteriorly directed. The large reservoir is situated anteriorly in the right-hand side of the cell and the nucleus is near the midline of the left-hand side. One cell observed.

Remarks. Lackey (1962) described Pentamonas spinifera Lackey, 1962 which is about 35 Mm long. His description is not detailed, but is of organisms which resemble those described here in having one emergent fl agellum, a rigid body and four protrusions, and in being fl attened. We transfer Pentamona s spinifera to Petalomonas . It is similar to P. raiula Larsen and Patterson, 1990 in having protrusions and one ridged ventral groove, but is distinguished by its larger size, and in having four hyaline protrusions and three fi ne dorsal ridges. Petalomona s spinifera is distinguished from other species of Petalomonas by its four protrusions.