Male gonial chromosome complements of B. pyramidalis (n=12, m, XO) and O. s. duaricus (2n=22, n=12,13, m, neo-XY), are briefly described on the basis of material from Dehra Dun Valley, U.P., India. Some speculations on the possible origin of the reduced chromosome number and on the neo-XY mode of sex determination in the latter species are offered. The two species have not been previously examined cytologically and are new records for the fauna of the Dehra Dun Valley.