Abstract
Examination of material from Lake Baikal revealed several species of the genus Stephanodiscus Ehrenberg in addition to the common genera Cyclotella (Kütz.) Bréb. and Aulacoseira Thwaites. One of the diatoms found closely resembled the recently described taxon, S. inconspicuus Mak. & Pom. (in Makarova & Pomazkina 1992). This diatom has several unusual features which makes us question its inclusion in the genus Stephanodiscus. On the basis of our investigation we have erected a new genus Crateriportula Flower & Håkansson nov. gen. into which we have transferred S. inconspicua as the type species.