Morphology and molecular phylogeny of Antarctic Paraholosticha muscicola (Kahl, 1932) Wenzel, 1953 (Protozoa, Ciliophora, Stichotrichida)

Abstract

Paraholosticha muscicola Kahl, 1932 represents the type species of this genus. However, a high variation on morphology of the type species (among populations in P. muscicola) obscures the inter-specific borders in the genus Paraholosticha. In this study, Antarctic population of P. muscicola was collected from a soil sample near the King Sejong station in Antarctica and identified based on live cell observation, protargol impregnation, and SSU rRNA gene sequence comparison to clarify the taxonomic borders for species identification. Antarctic population of the ciliate P. muscicola was morphologically characterized by the following features: cell size 100-130 μm × 45-55 μm in vivo; elongated ellipsoidal shape, flexible but not contractile; contractile vacuole in mid-body near left cell margin; 1220 coronal, 1-3 buccal cirri, and 4 ventral cirral rows; 3 complete dorsal kineties, 1 left and 1 right marginal cirral rows; 2 macronuclear nodules and 2-13 micronuclei; and transverse and caudal cirri lacking. Paraholosticha muscicola has a relatively broad range of morphological variation and shows the overlapped morphological features with <em>P. lichenicola</em> Gellert, 1955 implying a junior synonym or presence of cryptic species within <em>P. muscicola.</em> Here we report the morphology of the Antarctic <em>P. muscicola </em>with the SSU rRNA gene sequence to provide a potential reference capable of species identification. The gene information is the first record in Paraholosticha, even in the family Keronidae Dujardin, 1840.