Morphology and molecular phylogeny of an Antarctic population of Paraholosticha muscicola (Kahl, 1932) Wenzel, 1953 (Ciliophora, Hypotricha)

Abstract

The morphology of an Antarctic soil population of<em> Paraholosticha muscicola</em>, type species of <em>Paraholosticha</em>, is described from life and after protargol preparation. The data agree rather well with that of relevant descriptions, but the total variability of several features is relatively high in this species. <em>Paraholosticha ovata</em> and <em>P. lichenicola</em> are very likely junior synonyms. In addition, we sequenced the SSU rRNA gene of <em>P. muscicola</em> and thus we can estimate for the first time the phylogenetic position of a member of the Keronopsidae, the sole hypotrichs that divide in cysts. The molecular data basically support the position derived from morphological concepts, that is,<em> P. muscicola </em>branches off outside the Dorsomarginalia because kinety fragmentation and dorsomarginal rows are lacking. However, as in many other molecular analyses, discrepancies with morphology-based hypothesis are present. The misclassification of Paraholosticha and its sister-group Keronopsis in the Keronidae, with Kerona pediculus as type species, is discussed.