Taxonomy and molecular phylogeny of four karyorelictid species belonging to the genera Apotrachelocerca and Tracheloraphis (Protozoa: Ciliophora), with descriptions of two new species

The taxonomy and phylogeny of four trachelocercid ciliates, Apotrachelocerca orientalis sp. nov., Tracheloraphis apoligostriata sp. nov., T. oligostriata and T. prenanti, isolated from marine habitats in Qingdao, China, were studied. The new species, A. orientalis sp. nov., can be distinguished from its most closely related congener, A. arenicola, by the absence of cortical granules and its conspicuously different SSU rDNA sequence. Tracheloraphis apoligostriata sp. nov. differs from the similar T. oligostriata by its body shape, distribution pattern of the cortical granules and SSU rDNA sequence. Based on available data, we suggest that T. prenanti can be defined by its colourless, globular cortical granules, which indicates that this species should be removed from the T. phoenicopterus-complex. Phylogenetic analyses based on SSU rDNA sequence data indicates that: A. orientalis sp. nov. groups with A. arenicola with full support, together sister to all other trachelocercid species; and T. cf. phoenicopterus, T. prenanti, T. oligostriata and T. apoligostriata sp. nov. form a clearly outlined clade.