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SPECIES Otomys irroratus

Author:Brants, 1827.
Citation:Het Geslacht der Muizen: 94.
Common Name:Southern African Vlei Rat
Type Locality:South Africa, Western Cape Province, Cape Town district, near Constantia (fixed by A. Smith, 1834:149, in supplying replacement name typicus; see Meester et al., 1986:250).
Distribution:Mesic savannah and grasslands of southern Africa—S Western Cape Province to Limpopo Province, South Africa; disjunct populations in W South Africa and in E Zimbabwe and contiguous Mozambique (De Graaff, 1981:146).
Status:IUCN – Lower Risk (lc).

Bohmann (1952) established a broad, improbably polymorphic definition of O. irroratus, including some 23 subspecies, a concept further enlarged by Dieterlen (1968) and Petter (1982) and collectively enveloping the following forms here (and elsewhere) treated as separate species (see individual accounts): O. anchietae, O. angoniensis, O. barbouri, O. burtoni, O. cuanzensis, O. dollmani, O. jacksoni, O. laminatus, O. maximus, O. orestes, O. tropicalis, O. typus, and O. uzungwensis. Although followed to a greater or lesser extent (e.g., Delany, 1975; Honacki et al., 1982; Kingdon, 1974b), such an inclusive species construct has been refuted by others who identify O. irroratus proper as a species indigenous to southern Africa, south of the Zambezi River (e.g., De Graaff, 1981; Meester et al., 1986; Misonne, 1974; Taylor and Kumirai, 2001). Morphometrically distinguishable from East African forms, such as O. typus and O. tropicalis, and M3 characteristically possessing 6 laminae compared with 7-8 in those forms (Dollman, 1915; Thomas, 1918b; Taylor and Kumirai, 2001).

A subject of intensive investigation of intraspecific patterns of differentiation, O. irroratus sensu stricto is becoming a model organism for pursuit of evolutionary questions. Some results suggest "incipient speciation" among the population moieties so far identified (see overview and mapping of chromosomal races by Taylor, 2000b:Fig. 1), although the different data sets are not necessarily wholly concordant. G-banded comparisons reveal a karyotype that is highly derived (Robinson and Elder, 1987). Extensive cytogenetic variation (2n = 23-32; FN = 24-50) reported among South African population samples (Contrafatto et al., 1992a,b; Taylor, 2000b), complemented by examinations of variation in mtDNA (Lamb et al., 1996), protein electrophoresis (Contrafatto et al., 1997; Taylor et al., 1992; Taylor, 2000b), and reproductive isolating mechanisms (Pillay et al., 1992; 1995a,b). Correlation of cytotype distributions with climatic variables studied by Taylor et al. (1994b). Included saundersiae according to Taylor et al. (1993) but afterwards reinstated to species by Taylor et al. (in prep.); see that account. See Bronner et al. (1988, Mammalian Species, 308).




    auratus Wroughton, 1906
    bisulcatus F. Cuvier, 1829
    capensis G. Cuvier, 1830
    coenosus Thomas, 1918
    cupreoides Roberts, 1946
    cupreus Wroughton, 1906
    natalensis Roberts, 1929
    obscura (Lichtenstein, 1842)
    orientalis Roberts, 1946
    randensis Roberts, 1929
    saundersiae Roberts, 1929
    typicus (A. Smith, 1834)

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