Monodelphis (Mygalodelphys) adusta (Thomas, 1897)

Voss, Robert S., 2022, An Annotated Checklist Of Recent Opossums (Mammalia: Didelphidae), Bulletin of the American Museum of Natural History 2022 (455), pp. 1-77 : 26

Monodelphis (Mygalodelphys) adusta

( Thomas, 1897)

TYPE MATERIAL AND TYPE LOCALITY: BMNH 77.7.2.1, the holotype by original designation, consists of the skin and skull of an individual of unknown sex collected in “w.[est] Cundinamarca, in the low-lying hot regions” ( Thomas, 1897: 220), presumably in the valley of the Río Magdalena west of Bogotá, Cundinamarca department, Colombia.

SYNONYMS: melanops Goldman, 1912.

DISTRIBUTION: As currently understood (see Remarks), Monodelphis adusta occurs in eastern Panama, in the humid transAndean lowlands of northwestern South America, in the eastern Andean foothills (below about 1000 m) of Colombia and Ecuador, and in northwestern Amazonia (north of the Amazon and west of the Rio Negro). No published map illustrates the geographic range of this species as currently restricted by authors (see Remarks).

REMARKS: There is no adequate morphological description of Monodelphis adusta in the literature, although measurements of specimens from the cis-Andean lowlands of Ecuador and Peru (north of the Amazon) were tabulated by Voss et al. (2019), and cranial photographs are in Pavan et al. (2017). This species has never received critical revisionary attention, and it seems unlikely that it will survive such scrutiny without a dramatic reduction in geographic range. The current concept of the species is largely based on mtDNA sequence analyses (e.g., Solari, 2007; Pavan et al., 2014), but no sequence data are available from the trans-Andean lowlands, which is where the type was collected. Therefore, it is quite possible that the cis-Andean sequences hitherto thought to represent Monodelphis adusta might eventually be shown to belong to a different taxon.

Monodelphis peruviana was formerly treated (e.g., by Pine and Handley, 2008) as a subspecies of M. adusta , but phylogenetic analyses of sequence datasets have conclusively shown that these are not sister taxa. Instead, M. adusta (as represented by cis-Andean sequence data; see above) appears to be the sister species of M. reigi , whereas M. peruviana belongs to a clade that includes M. handleyi , M. osgoodi , M. ronaldi , and M. saci (see Pavan et al., 2014, 2016, 2017; Ruelas and Pacheco, 2022). Unfortunately, M. adusta and M. peruviana are not known to differ morphologically, so these names currently serve only as labels for genetically divergent but phenotypically similar specimens collected on opposite banks of the upper Amazon ( Voss et al., 2019).