Mastomys coucha (Smith 1834)

[Mus] coucha Smith 1834, Rept. Exped. Exploring Central Africa: 43.

Type Locality: South Africa, Northern Cape Province, between Orange River and Tropic of Capricorn (see Meester et al., 1986:286).

Vernacular Names: Southern African Mastomys.

Synonyms: Mastomys bradfieldi Roberts 1926; Mastomys breyeri (Roberts 1915); Mastomys limpopoensis (Roberts 1914); Mastomys marikquensis (Smith 1836); Mastomys sicialis Shortridge 1934; Mastomys silaceus (Wagner 1842); Mastomys socialis (Roberts 1913).

Distribution: Endemic to Southern African Subregion: South Africa (provinces of Eastern and Northern Cape, KwaZulu-Natal, Free State, Gauteng, Mpumalanga, and S and W Limpopo; also in Lesotho), S and W Zimbabwe, C Namibia (Granjon et al., 1997 b; Skinner and Smithers, 1990; Taylor, 1998).

Conservation: IUCN – Lower Risk (lc).

Discussion: Characterized by 2n = 36, FNa = 52-56, and a distinctive hemoglobin electromorph, M. coucha occurs sympatrically with M. natalensis in some areas but allopatrically in other regions of the Southern African Subregion (de Graaff, 1997 r); the latter is distinguished by a different hemoglobin pattern (Green et al., 1980), 2n = 32, FN = 54 (Volobouev et al., 2002 b), and three isozyme markers (Smit et al., 2001). The two species also differ in cranial, phallic, and spermatozoal morphology as well as reproductive behavior, growth patterns, ultrasonic vocalizations, and pheromones (Breed, 1995 a; Dippenaar et al., 1993; Jackson and van Aarde, 2003; Lavrenchenko and Baskevich, 1996; Skinner and Smithers, 1990; Taylor, 2000 b; and references cited therein), and can also be separated by principal component analysis of cranial and dental measurements (Dippenaar et al., 1993). Although the two are widely sympatric in southern Africa, their geographic ranges appear concordant with rainfall patterns, with M. coucha predominating in drier habitats characteristic of southwestern Africa and M. natalensis inhabiting more mesic regions in the east (Taylor, 2000 b, and references cited therein). Phylogenetic analyses of chromosomal data indicate M. coucha is more closely related to M. huberti and M. natalensis than to M. erythroleucus (Britton-Davidian et al., 1995). Karyotype of M. coucha is similar to M. shortridgei from NE Namibia and NW Botswana, but sex chromosomes differ and the two species can be distinguished by spermatozoal morphology (see references in Granjon et al., 1997 b). Synonyms listed are only those pertaining to samples from South Africa for reasons explained by Meester et al. (1986); of these, Robbins and Van der Straeten (1989) regarded marikquensis to be a Myomys (although Van der Straeten and Robbins, 1997, did not include it in their more recent allocation of holotypes to Myomys), and Robbins (in Meester et al., 1986) claimed it may be a species distinct from Myomyscus verreauxii. Reviewed by Granjon et al. (1997 b) and de Graaff (1997 r).