| Summary: | <i>Stephanodiscus makarovae</i>, a taxon originally described from Russia, is morphologically similar to several other taxa within <i>Cyclostephanos</i>, namely <i>C. invisitatus</i>, <i>C. delicatus</i> and <i>C. tholiformis</i>. However, it has not yet been transferred into <i>Cyclostephanos</i>, perhaps due to the difficulty in identifying it, as its original description is available only in the Russian language. To investigate its morphology, a detailed morphological comparison of <i>S. makarovae</i> and <i>C. invisitatus</i> was done from 286 SEM micrographs of 12 monoclonal strains. We performed a three-gene phylogenetic analysis with strains from eight additional taxa to independently confirm the position of <i>S. makarovae</i>. The morphology of <i>S. makarovae</i> shows key features of the genus <i>Cyclostephanos</i> and this attribution is supported by the phylogeny. Here we propose the transfer of the taxon <i>S. makarovae</i> to <i>Cyclostephanos</i>, considering the morphological and molecular data. According to both the molecular and morphological data, <i>C. delicatus</i> has a unique position within the genus; <i>S. makarovae</i> and <i>C. invisitatus</i> are morphologically very similar but genetically distinct. Furthermore, based upon the results, it was possible to reassign the authority of the transfer of <i>S. delicatus</i> into <i>Cyclostephanos</i>.
|
|---|