Definition and Diagnosis of a New Tribe of Sigmodontine Rodents (Cricetidae: Sigmodontinae), and a Revised Classification of the Subfamily

Abstract

A new tribe of sigmodontine rodents is formally defined and diagnosed. The tribe contains the extant genera Abrothrix (including Chroeomys), Chelemys, Geoxus, Pearsonomys, and Notiomys, a group of taxa distributed in the central and southern Andes and lowlands both east and west of the cordillera. The new tribe presents a unique combination of characters including nasals and premaxilla usually projected anterior to the incisors, moderately trumpeted; zygomatic plate with upper free border reduced or obsolete; and third upper molar reduced and sub-cylindrical in outline with an internal ring-like enamel fossette. Molecular phylogenetic analyses indicate that Abrothrix is sister to a clade containing the remaining genera of the new tribe.

The presence of Wilfredomys oenax (Rodentia: Cricetidae: Sigmodontinae) in São Paulo state, southeastern Brazil: a locally extinct species?

“…Although the phylogenetic position of these three genera remains unresolved, or at least controversial (see Reig, 1980;Pacheco, 2003;D'Elía et al, 2007;Ventura et al, 2013), some advances on Wiedomys and Juliomys were obtained, including new species (Oliveira & Bonvicino, 2002;Gonçalves et al, 2005;Costa et al, 2007) and new records (Pavan & Leite, 2011;Fonseca et al, 2013). Conversely, Wilfredomys Ávila-Pires (1960) and Pine (1980).…”

“…Although the presence of mesoloph/ id on molars classifies Wilfredomys among pentalophodont rodents associated to forested habitats (see details in Voss & Carleton, 1993;Weksler, 2006;Machado et al, 2013), this monotipic genus remains with an uncertain tribal affiliation (see D'Elía et al, 2007). Yet, only a few specimens from northern Uruguay and south and southeastern Brazil are known for this species.…”

Geographic distribution of the genera of the Tribe Oryzomyini (Rodentia: Cricetidae: Sigmodontinae) in South America: patterns of distribution and diversity

“…Throughout history, sigmodontine genera have been grouped in 7 to 9 tribes (for a revision of the generic contents of these tribes, see Reig, 1984;Smith & Patton, 1999;and D'Elía et al, 2007). However, for the last 15 years, morphological and molecular phylogenies have redefined and delimited those tribes (e.g., Braun, 1993, Phyllotini;Voss & Carleton, 1993, Oryzomyini;Smith & Patton, 1993Steppan, 1995, all tribes;D'Elía et al, 2003, 2006a, 2006b, 2007Pacheco 2003, Thomasomyini;Weksler, 2003, causing reconsideration of their definition and contents (see D'Elía et al, 2007), promoting the following tribal arrangement: Abrotrichini, Akodontini, Ichthyomyini, Oryzomyini, Phyllotini, Reithrodontini, Sigmodontini, Thomasomyini, Wiedomyini.…”

A new species of fish-eating rat, genus Neusticomys (Sigmodontinae), from Ecuador

“…400 species arranged in 86 genera (D'Elía and Pardiñas 2015). Traditionally, sigmodontine taxa have been arranged into tribes (Reig 1980;Musser and Carleton 2005;D'Elía et al 2007), one of which is the tribe Ichthyomyini comprising five genera and 17 species ranging from Bolivia, central Brazil, and the Guianas to southern Mexico (Jenkins and Barnett 1997;Musser and Carleton 2005). Ichthyomyines are small to mediumsized semiaquatic animalivorous rodents (Voss 1988), constituting a remarkably distinct group within the sigmodontine radiation.…”