Apusomonas australiensis Ekelund and Patterson 1997

Introduction

This species of Apusomonas has a pointed bulge at the left anterior corner of the theca. It also has a very flexible mastigophore. It has been reported from Australia.

Apusomonas australiensis is distinguished from A. proboscidea, the only other species in the genus, because of the projection from the anterior margin of the cell and because the mastigophore is more flexible and snake-like. Other characters of the two flagellates are very similar. A. australiensis is much more abundant than A. proboscidea, and intermediate forms were never observed.

Characteristics

This species is 6 - 10 µm long, dorso-ventrally flattened, irregularly ovate in outline, asymmetrical. The right side more rounded than the left, because the left anterior corner has a pointed bulge. The mastigophore is very flexible. It is approximately the same length as the cell and 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, and sheath plus flagellum is about half the cell length and about half as broad as the mastigophore. The distal third to quarter of the anterior flagellum is not ensheathed. A collar-like structure is seen where the mastigophore leaves the cell. The nucleus is situated posteriorly, a contractile vacuole is located in the mid-left-hand side of the cell. The cell glides over the substrate with a speed of about 10 µm/s. The ensheathed anterior flagellum beats rapidly to the left, the stroke covering an angle of about 45°.

References

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