Cytogenetic analysis, karyotype evolution and phylogenetic study of family Scarabaeidae (Coleoptera: Insecta)

The family Scarabaeidae comprises 25, 000 described species and is known cytologically by 404 species of 123 genera and 18 subfamilies. The present investigations recorded an account of 33 species representing 6 subfamilies, of which 17 species are new additions to this family. Scarabaeidae is conservative family in having the chromosome number 2n=20, sex determining mechanism 'Xyp' and metacentric chromosomes. Most of the cytogenetically known species have a chromosome number varying from 2n=8 in Eurysternus caribaeus to 2n= 36 in Gymnopleurus miliaris race-II (present study). The most prevalent sex determining mechanism is Xyp. The most common karyotype possessed by 175 species belonging to 18 subfamilies is 9AA+Xyp male, the most prevalent condition in Coleoptera as a whole. As many as 302 species showed a haploid number of 10. So, this can be very well designated as the „modal number‟ for Scarabaeidae.