Our specimens that were collected from differenthydrographic basins showed similarities among the popu-lations. The few differences included a denticle lengththat was higher in population C than in the other popu-lations but coincided with the description of Mitra andBandyopadhyay (2006). The border membrane in popula-tion B had a maximum value of 3.2 m, but this was similarto the arithmetic mean of populations A and C and the stud-ies by Mitra and Bandyopadhyay (2006) and Kibria et al