Chaos glabrum Smirnov and Goodkov, 1997
Diagnosis: Regularly orthotactic (monopodial-like with distinct lateral wrinkles) with bulbous uroid in active locomotion. Number of the nuclei 6-30 per cell (average 10). Nuclei biconvex, about 20 µm in diameter. Glycocalyx amorphous, up to 50-60 nm, of two distinct layers. Possesses mitochondrial heteromorphism.
Dimensions: Length of polypodial form about 500 µm; when orthotactic length 420-980 µm (average 816 µm), breadth 42-98 um (average 60 µm).
Ecology: Fresh water, north-western Russia. Bottom sediments of Lake Leshevoe (Valamo Island, Lake Ladoga), from depths of 0,5-1 m, 1994.
Differential diagnosis: In respect to the nuclear size and number, Chaos glabrum differs well from all known members of the genus Chaos, excluding C. nobile (both other species – C. carolinense and C. illinoisense have several hundred nuclei per cell). From Ch. nobile it differs well with stable orthotactic locomotive form, bulbous uroid and with the organization of the floating form. At the ultrastructural level, C. glabrum has a different structure of the cell coat than C. nobile.
