Morphology, taxonomy, ecology, and distribution of Cyclotella choctawhatcheeana prasad (Bacillariophyta)

A study of the widespread centric diatom Cyclotella choctawhatcheeana has revealed the variability of qualitative and quantitative morphological diagnostic features, as well as the presence of initial cells, and allowed us to obtain new data on the ecology and distribution of the species. On the basis of original and literature data, the diagnosis of the species is emended. The conspecificity of C. tuberculata , which is common for waterbodies of the former Soviet Union, with C. choctawhatcheeana , which is new for the flora of Russia, is confirmed, making it possible to bring the first species into the synonymy of the latter. The study of samples of C. caspia from the Caspian Sea which are similar in morphology and ecology allowed us to define the variability of some features of this species and its relationship with C. choctawhatcheeana and to evaluate its taxonomical importance for some of them.