Morphology and ontogeny of Tetmemena pustulata indica nov. subspec. (Ciliophora, Hypotricha), from the Thane Creek, Mumbai, India

Abstract

The morphology and ontogenesis of a novel stylonychid ciliate, Tetmemena pustulata indica nov. subspec., were investigated using live observation and protargol preparation. The new subspecies was isolated from a water sample collected from the Thane Creek, Mumbai, India. At first glance, T. pustulata indica looked very similar in morphology and ontogenesis to the well-known Tetmemena pustulata, however, on detailed investigation some non-overlapping features in the ciliature were identified, i.e., the numbers of cirri in marginal rows, adoral membranelles, and bristles in dorsal kineties. These morphometric differences justified the separation at subspecies level. Furthermore, the resting cysts are different, i.e., with smooth external layer in T. pustulata indica whereas spinous in the nominotypical subspecies T. pustulata pustulata. The Venezuelan population of T. pustulata described by Foissner corresponds very well with the Indian population in the ciliature; however, the information on the resting cyst is lacking for the former. Our study presents an example of a cyst subspecies among hypotrich ciliates, and thus extends the concept which has been mainly reported for spathidiids.

Keywords: Cryptic species; Cyst species; Ontogenesis; Resting cyst; Tetmemena pustulata; Thane creek (Mumbai).