Pleurotricha curdsi (Shi, Warren and Song 2002) nov. comb. (Ciliophora: Hypotrichida): morphology and ontogenesis of an Indian population; redefinition of the genus
Abstract:The oxytrichid ciliate Pleurotricha curdsi (140 × 64 μm) is widely distributed in the tributaries of the river Yamuna in Delhi. The vegetative ciliature consists of 20 frontal-ventral-transverse (FVT) cirri (9 frontal, 6 ventral and 5 transverse), two rows of right marginal cirri (RMC) and one row of left marginal cirri, four dorsal kineties, two dorsomarginal rows and three caudal cirri (CC), as well as the usual adoral zone of membranelles and two undulating membranes. A morphometric comparison between the Indian and Chinese populations of P. curdsi shows significant strain differences. On the basis of its morphological and morphogenetic features P. curdsi qualifies to be an oxytrichid sensu stricto. However, the presence of 20 FVT cirri in this species is a non-conforming feature as all other members of this group have been reported to possess 18 or <18 FVT cirri. The FVT cirri are formed ontogenetically from 6 FVT primordia, which involve 5 parental cirri as in the Stylonychia (= Tetmemena) pustulata-vorax (= bifaria) pattern. The two RMC rows are formed from a single primordium that arises in the outer parental RMC row and later splits into two. Morphogenetic study shows unequivocally the presence of three CC which are formed typically at the posterior ends of dorsal kineties 1, 2 and 4, but their subsequent alignment with the outer RMC row renders it difficult to distinguish them from the latter. Thus, certain new and confirmatory features reported in this study have necessitated a revised characterization of the genus.
Document Type: Research Article
Publication date: September 1, 2003