Morphological, morphometric and genetic variation among cryptic and sympatric species of southeastern South American three-striped opossums (Monodelphis: Mammalia: Didelphidae)

Abstract

Monodelphis is the most diverse genus of the family Didelphidae, whose systematics and taxonomy have not yet been well established. Two of the included species, Monodelphis americana and M. iheringi, are difficult to distinguish because both present three dorsal black stripes. Furthermore, they show intra- and interspecific variation related to body size and pelage coloration. Because this variation is not well understood, there are problems in correctly identifying these species, which remain poorly collected and thus rare in zoological collections. This study evaluated the morphological and genetic variations in a sample of striped opossums from a single location in southeastern Brazil to understand if the morphological variation observed in individuals from the same location was indicative of the existence of more than one taxon. The comparative analyses of a series from this single locality with museum specimens of other locations revealed variations in the skin and skull qualitative characters that were related to age and sex. Morphological comparisons led to the identification of two morphogroups, which were corroborated by molecular data; the analysis of cytochrome b sequences indicated the existence of two clades, with an average divergence of 14%. Thus, the results support the existence of two taxa in the sample, defined as M. americana and M. iheringi. We confirmed the sympatry of these two species in a location in southeastern Brazil, presented morphological diagnostic characters to distinguish the two species, provided novel phylogenetic information on the group, and also demonstrated the existence of important intra- and interspecific morphological variations related to sexual dimorphism and ontogeny in the group. These results significantly contribute to information on the systematics of the genus.

A Revised Subgeneric Classification of Short-Tailed Opossums (Didelphidae:Monodelphis)

“…Additionally, we summarize subgeneric patterns of distribution and sympatry consistent with our previously published biogeographic analyses (Pavan et al, 2016). 2013; Duda and Costa, 2015;Pavan, 2015) as well as other characters newly described herein. Descriptive terminology that we use to describe external and craniodental morphology in this report follows Cope (1880), Gregory (1910), Archer (1976), Wible (2003), and Jansa (2003, 2009).…”

A New Species ofMonodelphis(Didelphimorphia: Didelphidae) from the Brazilian Atlantic Forest

“…Although altitudinal data are not recorded on any specimen labels, maps and other sources of geographic information (e.g., Hijmans et al, 2005) suggest that elevations at localities where the species has been collected range from about 790 to 2380 m. Presumably, M. pinocchio is a montane species. The fact that so few representatives of M. pinocchio are available in collections might be due to either a scarcity of this species in nature or the almost exclusive traditional use of live traps for mammal inventories (such traps are known to be ineffective for capturing some species of Monodelphis; Pardini and Umetsu, 2006;Umetsu et al, 2006;Duda and Costa, 2015). Of the eight specimens reported here, six were collected in the past 15 years, soon after pitfall traps began to be more widely used for collecting small ter- restrial mammals in South America (Voss et al, 2001;Pardini, 2004;Umetsu et al, 2006).…”

“…With the description of Monodelphis pinocchio and the new synonymies suggested by recent molecular analyses 5 , five valid species of Monodelphis are now known from the Atlantic Forest of southeastern Brazil. Among these species, sympatry has been observed for all possible pairwise combinations (table 2), although syntopy (same-habitat occupancy) is confirmed only for M. iheringi and M. americana (at Reserva Biológica Duas Bocas, Espírito Santo; Duda and Costa, 2015). Remarkably, four Atlantic kunsi" are said to be sympatric at the Floresta Nacional de Carajás in northern Brazil (Martins et al, 2012).…”

“…Records of sympatry among Atlantic Forest Species of Monodelphis. Espírito Santo, Cariacica, Reserva Biológica Duas Bocas(Agrizzi et al, 2012;Duda and Costa, 2015). Rio de Janeiro, Parque Nacional do Itatiaia (this report: M. pinocchio AMNH 61547).…”

An Annotated Checklist of Recent Opossums (Mammalia: Didelphidae)

“…SyNonyMs: brasiliensis Erxleben, 1777; brasiliensis Daudin (in Lacépéde, 1802); rubida Thomas, 1899;trilineata Lund, 1840;tristriata Hliger, 1815;umbristriata Miranda-Ribeiro, 1936. DIsTRIBUTION: Monodelphis americana is known from the right bank of the Tocantins in eastern Para southward along the rainforested (or formerly rainforested) Atlantic coast of Brazil to Santa Catarina; the range of this species also extends inland along gallery-forested rivers into the Cerrado (Pine and Handley, 2008: map BF) REMARKS: See Duda and Costa (2015) for a morphological description, measurement data, and comparisons with Monodelphis iheringi, a superficially similar and closely related sympatric congener. The names brasiliensis, trilineata, and tristriata are all based, directly or indirectly, on the same 17th-century description authored by Marcgraf (Pine and Handley, 2008), so they are objective synonyms of M. americana.…”