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 Paraholosticha muscicola, type species of Paraholosticha, 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. Paraholosticha ovata and P. lichenicola are very likely junior synonyms. In addition, we sequenced the SSU rRNA gene of P. muscicola 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, P. muscicola 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.