The demise of the genus Scotiellopsis Vinatzer (Chlorophyta)

Abstract

The genus Scotiellopsis was established in 1975 by Vinatzer for a newly described species Scotiellopsis rubescens, but after revision by Puncochařova & Kalina in 1981 it included five species. The genus comprises coccoid green algae typically with apical thickenings and meridional ribs. Its similarity to another genus, Coelastrella Chodat, was noted, and indeed, two Scotiellopsis species were formally transferred to the genus Coelastrella on the basis of molecular evidence. Here we studied authentic strains of two more Scotiellopsis species, including the type species S. rubescens, to resolve the taxonomic status of the genus. Both 18S rDNA and ITS2 sequences indicate that S. rubescens cannot be separated from Coelastrella species on the generic level. We therefore propose a new combination Coelastrella rubescens, rendering Scotiellopsis a junior synonym of Coelastrella. The second species studied, Scotiellopsis reticulata, is shown to be closely related, if not conspecific, with Scenedesmus rubescens or Scenedesmus dissociatus representing the (sub) genus Acutodesmus. The position of the remaining Scotiellopsis species, Scotiellopsis levicostata, remains uncertain due to a lack of a culture.