Description of a new oxytrichid ciliate, Oxytricha buxai n. sp. and redescription of O. quadricirrata Blatterer and Foissner, 1988 based on morphology and 18S rDNA analyses.

The morphology of a new oxytrichid ciliate, Oxytricha buxai n. sp., isolated from a soil sample collected from the Buxa Tiger Reserve, West Bengal, India, was studied based on live observation and protargol impregnation. The new species is characterised by a body size of 85×35 µm in vivo, two macronuclear nodules with one or two micronuclei attached at variable positions, a few colourless cortical granules scattered throughout cortex, adoral zone of membranelles about 35% of body length with 26 membranelles on average, about 18 cirri in left and 16 cirri in right marginal row, right marginal row starts at the level of buccal vertex, usually 18 frontoventral transverse cirri, five dorsal kineties including one dorsomarginal row, three caudal cirri. Further, a redescription based on live and protargol-impregnated specimens of Oxytricha quadricirrata Blatterer and Foissner, 1988, isolated from a moss sample collected from the Kangra district, Himachal Pradesh, India, is provided. The Indian population of O. quadricirrata is similar in morphology to the type population. However, the dorsal side shows some variation, i.e., the presence of a second dorsomarginal row with one or two bristles and incomplete fragmentation of dorsal kinety 3 (vs single dorsomarginal row and complete fragmentation). The resting cyst is spherical and about 20 µm across, with a wrinkled surface. Morphogenesis is in typical Oxytricha pattern. Based on 18S rDNA, phylogenetic analyses show Oxytricha to be a polyphyletic genus. Further, O. quadricirrata clusters away from O. granulifera, thereby supporting the validity of the former.