Variation in the nucleolar organiser regions of the long-tailed giant rats (Rodentia, Muridae, Genus Leopoldamys) in Malaysia

Abstract

The nucleolar organiser regions of Leopoldamys ciliatus and L. sabanus from Peninsular Malaysia were studied by silver-staining. Three pairs of Ag-NORs were present in L. ciliatus while L. sabanus had four pairs of Ag-NORs. The two subacrocentric pairs were similar in these species. L. ciliatus had a metacentric pair while L. sabanus had two acrocentric pairs. Of the two acrocentric pairs in L. sabanus, the medium-sized autosome had the NOR located at the terminal part of the long arm. The complement of NORs in L. ciliatus and L. sabanus also differ from the published records of five pairs (two subacrocentric, two acrocentric, one metacentric) for L. edwardsi and three pairs (two subacrocentric, one acrocentric) for L. neilli from Thailand. Nucleolar organiser regions thus serve as an adjunct to delimit L. ciliatus from phenotypically similar species L. edwardsi, L. neilli, and L. sabanus. © National University of Singapore.