Apusomonas proboscidea Aléxéieff 1924

Introduction

This species of Apusomonas is distinguished by having a rounded body. It has been reported from Australia and Europe.

A. proboscidea seems to be a typical, common soil flagellate (Vickerman et al. 1974, Ekelund and Patterson, 1997). It has only been reported a few times from aquatic habitats: from freshwater, under the name Rostromonas applanata (Karpov and Zhukov, 1980), and from estuarine habitats (unpublished data).

Characteristics

Cells are 7 - 8 µm long, dorso-ventrally flattened, roundish to slightly ovate in outline. A flexible mastigophore, approximately the same length as the cell, arises in a cavity about one third of the cell length from the posterior end. The ensheathed anterior flagellum arises at the distal end of the mastigophore. The sheath plus flagellum are about half the cell length and about one third as broad as the mastigophore. The last half to one third of the anterior flagellum is not sheathed. There is a collar-like structure where the mastigophore leaves the cell anteriorly. The nucleus is situated in the posterior of the cell, a contractile vacuole is located to the left hand side of the cell and near the middle. The cell glides over the substrate, the flagellum beats rapidly to the left, the stroke covering an angle of about 45°, the mastigophore is held stiff most of the time and moves only when the cell changes direction.

References

Ekelund, F. and Patterson, D. J. 1997. Some flagellates from a cultivated garden soil in Australia. Archiv für Protistenkunde 148:461-478.

Karpov S. A.& Zhukov, B. F. 1980. Rostromonas applanata gen. et sp. n. (Zoomastigophorea, Protozoa) a new representative of freshwater fauna. Zoologischkei Zhurnal 59:1733-1735. (in Russian)

Karpov S. A.& Zhukov, B. F. 1986. Ultrastructure and taxonomic position of Apusomonas proboscidea Aléxéieff. Archiv für Protistenkunde 131:13-26

Vickerman, K. Darbyshire, J.F. and Ogden, C.G., 1974: Apusomonas proboscidea Aléxéieff 1924, An unusual phagotrophic flagellate from soil. Archiv für Protistenkunde 116:254-269.