Heteronema ovale Kahl, 1928

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 : 502-507

Heteronema ovale Kahl, 1928

(fi gures 6d, 8a -e)

Description. Cell outline ovate, cell length 15-30 Mm, fl attened. The pellicular striations follow a S-helix on the ventral and dorsal faces of the cell and may or may not have associated refractile bodies. This species is capable of vigorous squirming movements. Two fl agella are of almost equal length and are slightly longer than the cell. The posterior fl agellum has a knob at its base and is stronger than the anterior fl agellum. The ingestion organelle has two rods, eats diatoms. The reservoir and nucleus are located in the left side of the cell. Cells move by skidding or by vigorous squirming in contact with substratum. Sometimes common. Description based on the observation of 20 cells.

Remarks. Generally, our observations are in good agreement with the original description of Kahl (1928). As noted above under comments to H. larseni , the organism described by Larsen (1987) and by Larsen and Patterson (1990) as H. ovale is not, in our view, the same species as described by Kahl. Heteronema ovale described by Ekebom et al. (1996) may be the same species. Heteronema ovale can be confused with H. exaratum Larsen and Patterson, 1990 and H. larseni Lee and Patterson , n. sp. because they have a similar general appearance. However, H. ovale can be distinguished from H. exaratum because H. exaratum has differing dorsal and ventral pellicular striations and more vigorous squirming movements, but is not distinguished by size because there is considerable overlap. Heteronema ovale is distinguished from H. larseni by the vigorous squirming movements of H. ovale , and the pointed posterior end of H. larseni . Heteronema ovale is likely to be smaller.

Jenningsia fusiforme ( Larsen, 1987) Lee et al., 1999 (fi gures 12c, 13g, h)

Description. Cell usually elongate, 30-35 Mm long, with a narrowed anterior end and a rounded posterior end. With delicate pellicular striations following an S-helix. One fl agellum emerges from a slit opening of the fl agellar canal, is 40-50 Mm long and beats mostly at anterior end. A refractile arc-like structure is located close to the slit-like opening of the fl agellar canal. The fl agellar pocket is located in the fi rst third of the cell on the left-hand side. The ingestion organelle with two fi ne rods is obvious. The nucleus is situated in the posterior of the cell. Moves by gliding or squirming movement. Relatively common. Description based on observations of nine cells.

Remarks. Previously reported cell length ranges from 25 to 45 Mm. This species was reported from marine sites in subtropical and tropical Australia, Brazil, Danish Wadden Sea, and Fiji as Peranema fusiforme ( Larsen, 1987; Larsen and Patterson, 1990; Ekebom et al., 1996; Patterson and Simpson, 1996). Evidence has now been presented that the`short recurrent fl agellum’ is now part of the internal architecture of the mouth region and this species has since been assigned to the genus Jenningsia ( Lee et al., 1999) . Our observations on this species are broadly in agreement with those of previous observers. This species is similar to Jenningsia macrostoma (see below), but it can be recognized by its smaller size and less developed ingestion organelle.

Jenningsia macrostoma ( Ekebom et al., 1996) Lee et al., 1999 (fi gures 12e, 13j, k)

Description. Cell length about 80 Mm, anteriorly narrowed or pointed and posteriorly rounded, very metabolic. With about 50 fi ne pellicular striations following a S-helix. Ventral striations are more distinct than the dorsal ones. The fl agellar pocket is situated on the left ventral face of the cell and is up to 24 Mm long. The fl agellum is as long as the cell and beats freely. The ingestion organelle with two well-marked rods is strongly developed and up to 20 Mm long. The rods appear hollow. There is a refractile arc-like structure associated with the slit-like opening of the fl agellar canal. The nucleus is situated in the posterior end of the cell. Refractile granules are randomly distributed inside the cell. This species ingested eukaryotic cells as long as 16 Mm. Glides with a squirming movement. Two cells observed.

In addition we observed three cells measuring 100-114 Mm and with a narrow aspect. The ingestion organelle seems less developed than the cells described above and the nucleus is situated in the mid-position of the cell.

Remarks. This species was fi rst described from a marine site in tropical Australia by Ekebom et al. (1996) with lengths of 64-87 Mm as Peranema macrostoma . As with Jenningsia fusiforme (above) we note that the arc structure associated with the fl agellar canal is not a fl agellum but part of the architecture of the mouth, and for this reason this species was transferred to the genus Jenningsia ( Lee et al., 1999) . We note that the Peranema measuring 70 Mm long found in Brazil by Larsen and Patterson (1990) may belong to this species. The smaller cells observed by us comply well with the description of Ekebom et al. (1996). Ekebom et al. (1996) observed one cell measuring 114 Mm from One Tree Island (Patterson, unpubl. notes) and which probably corresponds with the larger cells observed here. These can be tentatively assigned to J. macrostoma . This species resembles J. fusiforme in general appearance but J. macrostoma is bigger and has larger rods in the ingestion organelle.