Peter John Taylor, Albert Kumirai, Giancarlo Contrafatto
Species with fuzzy borders: the taxonomic status and species limits of Saunders' vlei rat, Otomys saundersiae Roberts, 1929 (Rodentia, Muridae, Otomyini)
The taxonomic status and species limits of the South African-endemic rodent
species Otomys saundersiae were revised using G-banding karyotypic analysis,
assessment of pelage colour and craniodental traits, multivariate analysis of
eight cranial distance measurements, and geometric morphometric analysis
of 11 landmarks of the dorsal image of the skull. In the Western Cape, the
recognized subspecies Otomys saundersiae karoensis differed in karyotype from
sympatrically-occurring populations of O. irroratus (cytotype "C") in having
six (as opposed to four) pairs of biarmed chromosome pairs and in the
absence of pair number 14. Discriminant analysis of linear craniometric
variables in positively identified (karyotyped) samples of Otomys irroratus and
Otomys s. karoensis separated the two species without any overlap, as did
pelage colour and certain qualitative cranial characters such as nasal angle;
such clear-cut differences however were not apparent between unkaryotyped
samples of O. s. saundersiae and O. irroratus from the Eastern Cape. Centroid
size (from geometric morphometric analysis of cranial landmarks) was
significantly correlated with both non-affine and affine components of skull
shape, indicating strong allometric effects. Both cranial shape and size differed significantly between Western Cape O. s. karoensis and O. irroratus; size, but not shape, varied significantly between Eastern Cape O. s. saundersiae and O. irroratus. Within both currently recognized species, significant geographical differences in cranial shape were detected between
eastern and western Cape populations occupying distinct ecological biomes.
Problems with defining species limits in this complex case were discussed
with reference to available data and alternative species concepts.
Mammalia, Walter de Gruyter
Print ISSN: 0025-1461
Volume: 69, 12/2005
Pages: 297 - 322
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