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SPECIES Calomys callosus

Author:Rengger, 1830.
Citation:Naturgesch. Säugeth. Paraguay: 231.
Common Name:Big Laucha
Type Locality:Paraguay, Neembucú Dept., banks of Río Paraguay about 27º S latitude (refined as opposite mouth of Río Bermejo by Hershkovitz, 1962:172, and restricted as vicinity of Ciudad Pilar by Contreras, 1992:2).
Distribution:Dry and subhumid areas in E Bolivia, N Argentina, Paraguay, and contiguous WC Brazil; isolated records in SE and E Brazil (see Salazar-Bravo et al., 2002a).
Status:IUCN – Lower Risk (lc).
Comments:According to Hershkovitz (1962), callosus also encompassed boliviae (see species account), callidus (see species account), fecundus (see C. boliviae), and venustus (see species account). Others have referenced, without explanation, muriculus (Williams and Mares, 1978) as a separate species, although Reig (1986) did not; specimens collected near the type locality of muriculus are interspersed among samples of C. callosus proper in cytochrome b sequence analyses (Salazar-Bravo et al., 2002a). Especially see Salazar-Bravo et al. (2002a:194-195) for karyotypic amendment of C. callosus (2n = 50, FN = 66; not 2n = 36, FN = 48 as reported by Pearson and Patton, 1976). Also see Contreras (1992) for review of conflicting interpretations of the type locality and the need to obtain topotypic material to confirm the identity of the species as currently understood. His recommendation is especially prescient today since the restricted type locality of C. callosus is extralimital to the distribution of the species as currently circumscribed (Salazar-Bravo, 2002a:Fig. 1).



    muriculus (Thomas, 1921)

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