Morphometric characterization of the Giant Pouched Rat (Cricetomys Waterhouse 1840) in the forest zone of South Western Nigeria
2008
Olayemi, Ayodeji | Akinpelu, Akinsola
This study was carried out to identify distinguishing morphometric characters between taxa from the genus Cricetomys in the rainforest. Specimens were captured from localities in the rainforest zone of South Western Nigeria, and 22 classic morphometric distances were taken on the skulls. Statistical analysis of morphometric data was carried out using principal component analysis and canonical variate analysis. In the principal component analysis, zygomatic width, rostrum depth, mandible length, incisive foramen length, and interorbital width represent the heaviest loading characters involved in separating male specimens of C. emini from C. gambianus. Among males, morphometric separation of these two species of Cricetomys was found to concur with pelage characterizations. Female specimens of C. emini and C. gambianus, however, could not be distinctly separated morphometrically, but nasal length, upper diastema length, rostrum depth, mandible length, mandible depth, zygomatic width, and parietal width are among the heaviest loadings involved in their partial separation. Moreover, morphometric data and pelage patterns do not produce identical characterizations of female specimens. Findings from this study reinforce the view that pelage characterizations are not entirely reliable in distinguishing taxa within Cricetomys. The morphometric characters identified in this study will contribute to more a reliable identification of giant pouched rat species within forests of Africa.
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