Monodelphis maraxina, THOMAS, 1923

Pavan, Silvia Eliza, Rossi, Rogerio Vieira & Schneider, Horacio, 2012, Species diversity in the Monodelphis brevicaudata complex (Didelphimorphia: Didelphidae) inferred from molecular and morphological data, with the description of a new species, Zoological Journal of the Linnean Society 165 (1), pp. 190-223 : 210-211

MONODELPHIS MARAXINA THOMAS, 1923

Monodelphis maraxina Thomas, 1923 was described for Marajó Island, in eastern state of Pará. Thomas (1923) suggested that M. maraxina is closely related to M. domestica . Subsequent authors agreed with him, some of which even regarded M. maraxina as a synonym of M. domestica (e.g. Cabrera, 1958; Emmons & Feer, 1990, 1997). However, Pine (1980) suggested that a relationship of M. maraxina with members of the M. brevicaudata group would be more reasonable on zoogeographical grounds. He also noted that the relative hairlessness of the tail and the buffy coloration of body sides are conditions shared with specimens of M. brevicaudata from the east bank of the Tapajós river (= M. glirina ). Recently, based on Pine’s (1980) view, Solari (2010) included M. maraxina in the M. brevicaudata group.

Our morphological analysis of the holotype of M. maraxina (BMNH 12.5.11.13) through photographs led us to conclude that this form undoubtedly belongs to the M. brevicaudata complex. The colour pattern observed in specimens of M. glirina from the east bank of the Xingu river shows a striking concordance with the original description of M. maraxina , and our analysis confirmed that these two forms have highly similar skin and skulls. Similarities between the faunas of the Marajó Island and the adjacent area at the eastern margin of the Xingu river are expected, as indicated by other vertebrate groups (e.g. Nascimento et al., 1991; Avila-Pires, 1995; Fernandes, Cardoso da Silva & Silva Jr, 1995; Ron, 2000). Furthermore, our recent field work at Marajó uncovered specimens of another species of the M. brevicaudata complex that is also present on the east bank of the Xingu river ( M. touan ), confirming that these areas are able to share species of short-tailed opossum.

Given the substantial morphological similarity between the holotype of M. maraxina and specimens of M. glirina from east of the Xingu river, and the evidence that these areas are able to share species of short-tailed opossum, we argue that M. maraxina may represent a geographical variant of M. glirina . However, as we have not performed molecular and direct morphological analyses of specimens regarded as M. maraxina , and because our general analyses are not conclusive with respect to M. glirina , which may represent a complex of species rather than an unique species, more accurate analyses are needed to answer this question. At this time, we maintain M. maraxina as a valid species included in the M. brevicaudata complex.