Rhabdomonas incurva

Rigid euglenid, cell outline cylindrical and curved, dorso-ventrally slightly flattened. Anterior end is rounded and slightly oblique, posterior end of cell is rounded. Cells are about 11 - 16 microns long. The opening of the apical canal is located laterally. With one flagellum which is about the same length as the cell, sometimes stretched straight out when the cell is at rest or after death. The pellicle has 4, 6 or 8 thin longitudinal grooves (spaced about 0.5 - 2 microns wide). Some cells have very delicate grooves (hard to see), other cells have distinct grooves. A nucleus was observed in or slightly posterior to the middle of the cell. A contractile vacuole is located in the anterior third either near the centre or to one side of the cell. Some cells contain two large ovale paramylon grains in the aneroir part of cell and some small roundish in the posterior part of cell, other cells contain also a few cylindrical paramuylon grains in the middle of cell. During swimming cells rotate around the longitudinal axis.