Karyotypic Analysis of Oniticellus pallens (Scarabaeinae: Scarabaeidae: Coleoptera)

Standard staining, silver staining, and C-banding techniques were used to study the chromosomal structure of Oniticellus pallens belonging to family Scarabaeidae and the subfamily Scarabaeinae. The karyotype consisted of 20 chromosomes which displayed a meioformula of 9AA+Xyp. Chromosomes in the subfamily Scarabaeinae were mostly metacentric and submetacentric, showing conservative character which has been supported by Modal Chromosome Number (MCN). In Oniticellus pallens along with its meta-, submeta- centric nature further supports this. Analysis of the constitutive heterochromatin (CH) revealed large chromosomal fragments located in pericentric region of spermatogonial metaphase and terminal regions of dumbbell-shaped bivalents in metaphase I. Silver staining showed dense spots in the zygotene stage of prophase I, which were associated with nucleolar organizer regions. The Chiasma frequency and terminalisation coefficient revealed close relationship of Oniticellus pallens with other species of the subfamily Scarabaeinae. It has been concluded that the structural changes in the chromosomes, distribution patterns of constitutive heterochromatin, and localization of nucleolar organizer regions on the chromosomes are equally important in the speciation of beetles and other groups of insects.