Taxonomic status of the nominal forms assigned to Necromys lactens (Rodentia, Cricetidae) as revealed by molecular and morphometric evidence

<jats:title>Abstract</jats:title> <jats:p>Necromys is a genus of sigmodontine rodent that inhabits grasslands and scrublands in South America. Eight extant species are recognized in the genus; one of these is Necromys lactens, which inhabits high-elevation grasslands in the Yungas from south-central Bolivia to northwestern Argentina. Morphological variation in N. lactens has been recognized by the description of three nominal forms. Geographically structured genetic diversity also has been observed, but a thorough revision of these nominal forms within an integrative framework has yet to be performed. We conducted a phylogeographic assessment based on an 801 base-pair fragment of the cytochrome-b gene that guided morphometric analyses (univariate and multivariate comparisons) of patterns of geographic variation in the species, and the distinction of its nominal forms. Haplotypes of N. lactens form a well-supported and geographically structured clade. Within it, there ar