Description of Anictostoma grelli
provided by BioPedia
Living cells about 40-70 x 15-30 microns. Shape highly variable, frequently pentagonal with narrowed postoral portion, but sometimes broadly ellipsoid or fusiform. Prepared specimens usually ovoid or fusiform as if contracted although living cells appear not to be contractile. Macronucleus near centre of cell, ellipsoid (2:1). Many large, spherical nucleoli, more rarely a single, coiled nucleolus. Micronucleus thorn-shaped, about 5 x 2 microns in living cells and attached to macronucleus. Contractile vacuole at posterior end; without collecting vesicles or canals; single excretory pore in centre of posterior pole. Cortex thin; very flexible, distinctly furrowed by somatic kineties. Between ciliary rows there are many about 1 microns sized spherical structures, presumably extrusomes, recognizable only after protargol impregnation. Cytoplasm colourless, contains some small, oblong crystals and few to many 1-3 microns sized, refractile globules. Feeds on small species of Colpoda, and occasionally on fungal spores. Movement rapid by rotation about main body axis. Somatic kineties follow a spiral coursing, preorally composed of ciliated dikinetids; anterior cilium lacking in postoral dikinetids. 5-8 postoral kineties alorzg posterior and left margin of oral apparatus. Preoral suture in median of cell, straight, very short. Vestibular kineties and diagonal groove lacking. Oral apparatus large, occupies anterior third of cell, vestibulum appears as conspicuous, bright patch in living cells. Left oral polykinetid small compared to size of cell, cilia about 8 microns long cilia are easy to see; inserts on left slope of vestibulum between ends of right oral ciliary field. Right oral polykinetid elliptical, narrowed ends insert on left slope of vestibulum, externally comprising 1-2 rows of ordered basal bodies, the cilia of which form an undulating membrane; internally basal bodies are not in an ovious pattern. Cytostomal slit sigmoid, in the centre of a vestibular trough. Resting cyst and morphogenesis not known.
