Chromosomal and banding studies in Sphaerium indicum (Bivalvia: Mollusca)

During the present study, mitotic chromosomes of freshwater snail Sphaerium indicum were studied using gills. The observed diploid chromosome number was 2n=30 consisting of 26 metacentric pairs and 04 submetacentric pairs respectively. Chromosomes were studied using Giemsa staining and two banding techniques viz. C-banding and Ag-NOR banding. Preliminary C-band studies revealed the presence of terminal blocks besides the presence of centromeric heterochromatin. The nucleolar organizer region (NOR) was found on one chromosome pair i.e. on the submetacentric chromosome pair no. 5. The cytogenetic relationship between S. indicum and other species of Veneroida was also discussed.