Morphology and phylogenetic position of the oxytrichid ciliates, Urosoma salmastra (Dragesco and Dragesco-Kernéis, 1986) Berger, 1999 and U. karinae sinense nov. sspec. (Ciliophora, Hypotrichia)

The morphology and infraciliature of two hypotrichous ciliates, Urosoma salmastra and U. karinae sinense nov. sspec., were investigated for populations collected from the surface of intertidal gravel in the Huguang Mangrove Forest, Zhanjiang, China and the upper 10 cm layer of soil in the Sangke Grass Land in the southern part of Gansu Province, China, respectively. Urosoma salmastra is characterized by its elongate-elliptical body with no tail-like structure; two macronuclear nodules; cortical granules colourless, less than 1 μm across, and arranged in short rows; adoral zone occupying 25% of body length in vivo; paroral conspicuously short and located in front of endoral. Urosoma karinae sinense nov. sspec. is characterized by its elongate-elliptical body with no tail; 2-4 macronuclear nodules; cortical granules colourless, less than 1 μm across, and arranged in short rows; adoral zone occupying 30% of body length in vivo; paroral shorter than, and located ahead of endoral. Phylogenetic analyses based on SSU rRNA gene sequence data suggest a close relationship between U. salmastra, U. karinae sinense nov. sspec. and Oxytricha granulifera within the Oxytrichinae assemblage.