Cosmarium botrytis is a species of green algae in the family Desmidiaceae.

It is a freshwater species with a worldwide distribution,[1] and has been recorded from all continents.

Cells are roughly ellipsoidal in outline with two semicells.

When viewed from the side or top, Cosmarium botrytis appears elliptical.

[2] Zygospores have been observed in Cosmarium botrytis: they are spherical and covered with short processes that are tipped with three (sometimes four) spines.