Taxonomic resolution of (Alveolata, Ciliophora, Hypotricha) sensu Sapra and Dass 1970 using an integrative approach.

The spirotrichean ciliate has previously been recorded in India although the descriptions are lacking in detail. It has been suggested several times that the Indian population, sensu Sapra and Dass, 1970 collected along the Delhi stretch of the River Yamuna, is identical to but this has never been confirmed due to insufficient data for the former. The present study includes detailed descriptions (classical and molecular) of populations of isolated from six locations along the River Yamuna, India. These include four from the Delhi stretch including that from which Sapra and Dass, 1970 isolated their population of . Due to the lack of a sufficiently detailed description, the taxonomic status of sensu Sapra and Dass, 1970 was not clear. Comparisons among the populations isolated in the present study with previous descriptions of and sensu Sapra and Dass, 1970 show only minor differences in morphometry, morphogenesis and in 18S rDNA sequences. The 18S rDNA sequences of all six populations had 99% similarity to both and . These findings support the contention that sensu Sapra and Dass, 1970 was misidentified and is a population of . This study supports the need for adopting an integrative approach based on morphological, morphogenetic and molecular data in order to understand species delimitation in ciliated protists.