Hidden diversity in Selenastraceae (Sphaeropleales, Chlorophyceae): Molecular phylogeny revealed a nannoplanktonic species, with the description of Viridiparva madeirensis gen. et sp. nov.

The simple morphology of the members of the family Selenastraceae, common in freshwater phytoplankton, has led to misidentifications. But the use of molecular tools is untangling their phylogeny and unveiling new genera and species hidden under the same morphotype or overlooked by microscopic analysis. Here we propose a description of Viridiparva madeirensis gen. et sp. nov., a small Selenastraceae member, based on the study of three strains by light, scanning and transmission microscopy and 18S rDNA and rbcL phylogenies. The phylogenetic analyses by 18S rDNA and rbcL show, respectively, that the closest relatives to Viridiparva madeirensis are Monoraphidium dybowskii and Raphidocelis microscopica, but with no or low statistical support. V. madeirensis is smaller than M. dybowski and has no cell wall incrustations typical for Raphidocelis. Thus, phylogeny and morphological analyses indicate a novel lineage within Selenastraceae. Furthermore, also reinforce the necessary revision of the genera within Selenastraceae, as Monoraphidium and Raphidocelis. Therefore study contributes to clarify the phylogeny and taxonomy of the family and add genetic sequences of neglected nanophytoplankton to GenBank, including one strain with known potential for biodiesel production.