Description of Polytomella

Cells colourless, with leucoplasts; cell wall absent; cells ellipsoidal, inverted ovoid or pear-shaped, or nearly spherical; 4 equal flagella; leucoplast(s) highly reticulate and branched, starch grains usually many, located peripherally in the posterior two-thirds of the cell; pyrenoid absent; eyespot present or absent; nucleus centrally located or anteriorly displaced; contractile vacuoles 2 or 4, anteriorly located; Golgi bodies perinuclear; asexual reproduction by longitudinal division of vegetative flagellate cells; cysts spherical with four-layered, thick cell wall; upon excystment each cyst releases a single, flagellate vegetative cell; sexual reproduction isogamous to form a quadriflagellate planozygote that produces four progeny cells by two perpendicularly oriented cell divisions; nutrition heterotrophic, able to grow on acetate but not on glucose; relatively rare in freshwater, found among rotting vegetation.