Sex-chromosome constitution and supernumerary chromosome in the large bandicoot rat, Bandicota indica (Rodentia, Muridae) from Peninsular Malaysia

Abstract

The Peninsular Malaysia taxon of Bandicota indica has a standard complement of 44 chromosomes, with medium-sized subacrocentric X and small submetacentric Y chromosomes. The present study reveals variation in the size and morphology of the X-xhromosome in B. indica with 2n = 44. The difference in size of the X-chromosome is attributed to variation in constitutive heterochromatin. Excepting the X-chromosome, the karyotype of the Malaysian taxon is similar to the Indian B. indica nemorivaga with 2n = 44. It differs from the Thailand taxon in the number of biarmed and uniarmed autosomes. A male specimen (with 45 chrosomes) of the Malaysian taxon possessed a supernumerary (B) chromosome which is identical to that reported in B. indica nemorivaaa.