Scapteromys aquaticus Thomas 1920

Scapteromys aquaticus Thomas 1920, Ann. Mag. Nat. Hist., ser. 9, 5: 477.

Type Locality: Argentina, Buenos Aires Prov., Isla Ella.

Vernacular Names: Argentine Swamp Rat.

Distribution: EC Argentina and E Paraguay.

Discussion: Retained as a species (e.g., Cabrera, 1961; Gyldenstolpe, 1932) until Massoia and Fornes (1964) realigned aquaticus as a subspecies of S. tumidus, a reallocation commonly observed in later systematic works (Corbet and Hill, 1991; Hershkovitz, 1966 c; Honacki et al., 1982; Musser and Carleton, 1993). Karyotypic differences consistently disclosed between aquaticus (2n = 32) and tumidus (2n = 24) have persuaded others to retain the two as distinct species (Brum et al., 1973; Brum-Zorilla et al., 1986; Gardner and Patton, 1976; Gentile de Fronza, 1970), and they are represented as genetically separable in phylogenetic studies of cytochrome b data (D’Elía et al., 2003, in press).