Chlorella sphaerica and its position in the Genus diplosphaera (Chlorophyta, Trebouxiophyceae)

Abstract

Morophological and molecular genetic analyses of green alga Chlorella sphaerica Tschermak-Woess (authentic strain), which represents the taxonomically critical species, the phenotypic similarity and phylogenetic close relation with the genus Diplosphaera Bialosuknia were foundbutthe significant difference from the genus Chlorella Bejerink was demonstrated. Discovery of new morphological features (presence of vegetative division, the ability to dyads and packages forming, as well as external mucous structures) indicates the position of Ch. sphaerica within the genus Diplosphaera. The analysis of nucleotide sequences of non-coding regions (ITS-1 and ITS-2) of nuclear-encoding ribosomal gene cluster confirms this conclusion. Based on these data the new nomenclature combination is suggested: Diplosphaera sphaerica (Tschermak-Woess) Karbovska et Kostikov, comb. nova (basionym: Chlorella sphaerica Tschermak-Woess).