Didelphis albiventris Lund, 1840

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 : 34

Didelphis albiventris Lund, 1840

TYPE MATERIAL AND TYPE LOCALITY: No specimens were mentioned in the original description, which was based on material obtained near Lagoa Santa (19.63° S, 43.82° W), Minas Gerais state, Brazil. However, a single specimen known to have been collected by Lund ( ZMUC L4) can perhaps be considered the holotype by monotypy.

SYNONYMS: bonariensis Marelli, 1930; dennleri Marelli, 1930; lechei Ihering, 1892; leucotis Wagner, 1847; paraguayensis J.A. Allen, 1902; poecilotis Wagner, 1842; poecilonota Schinz, 1844.

DISTRIBUTION: As currently recognized (see Remarks), Didelphis albiventris occurs in more or less open habitats—savannas, dry forests, anthropogenic clearings, etc.—in Brazil (south of the Amazon), eastern Bolivia, Paraguay, Uruguay, and northern Argentina (Cerqueira and Tribe, 2008: map 6).

REMARKS: Species limits within the Neotropical white-eared opossum group ( Didelphis albiventris , D. imperfecta , D. pernigra ) remain to be convincingly documented. Among other uncertainties, there has been no geographically comprehensive survey of mtDNA variation in this complex, so it is not even known whether these taxa are convincingly resolvable as reciprocally monophyletic haplogroups. 11 Additionally, diagnostic morphological differences are elusive. Didelphis imperfecta and D. albiventris , in particular, have broadly overlapping measurements (Lemos and Cerqueira, 2002: appendix II) and are said to be phenotypically distin-

11 Although Dias and Perini’s (2018) phylogenetic analyses of COI sequences from white-eared opossums recovered distinct haplogroups that they interpreted as support for the three currently recognized species, their albiventris sequences were all from southeastern Brazil, their imperfecta sequences were all from the Guianas, and their pernigra sequences were all from Ecuador. With such widely separated geographic samples, intraspecific isolation by distance is a plausible alternative explanation for their results.

guishable only by the extent of white on the pinnae (Cerqueira and Tribe, 2008). Although white ear markings are potentially useful for identification, they are known to vary within other species (e.g., D. virginiana ; Gardner, 1973), and the constancy of this difference between D. imperfecta and D. albiventris has never been quantified. The lack of unambiguously diagnostic morphological features in this complex and the consequent reliance on geographic criteria for species identification—as in Cerqueira and Tribe’s (2008) key—makes it difficult to assign names to specimens that have been collected well outside the previously documented ranges of these taxa. The white-eared opossums that Díaz and Willig (2004) reported from the vicinity of Iquitos is a relevant example that was discussed inconclusively by Cerqueira and Tribe (2008: 22).