Marmosa (Marmosa) macrotarsus (sensu Rossi, 2005)

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 : 13

Marmosa (Marmosa) macrotarsus

(Wagner, 1842)

TYPE MATERIAL AND TYPE LOCALITY: No type was designated in the original description, although Wagner (1847) mentioned two specimens collected by Johann Natterer on the Rio Madeira that have subsequently been regarded as syntypes. Pelzeln (1883), however, listed only one Natterer specimen of this species from the Rio Madeira. Tate (1933: 101) referred to this specimen as “ Vienna 195,” and called it a “co-type.” It is now cataloged as NMW B-2610 and consists of the skin and skull of an adult male (F. Zachos, in litt., 2 December 2021).

SYNONYMS: madeirensis Cabrera, 1913 (an invalid replacement name; see Remarks); musicola Osgood, 1913; quichua Thomas, 1899.

DISTRIBUTION: As recognized by Rossi (2005; see Remarks), Marmosa macrotarsus is an Amazonian species that occurs south of the Amazon and west of the Tapajós; reported collection localities are in rainforested lowlands and foothills (below 1900 m) in Peru, Brazil, and Bolivia ( Rossi, 2005: fig. 62).

REMARKS: Marmosa macrotarsus was ranked as a subspecies of M. murina by Tate (1933) who, however, used Cabrera’s (1913) replacement name for this taxon, and it was treated as a synonym of M. murina by Creighton and Gardner (2008a). Current recognition of M. macrotarsus as a valid species follows Rossi (2005), who provided a morphological description, tabulated measurement data, and carried out morphometric comparisons with other congeners. Subsequently, Gutiérrez et al. (2010) found that specimens geographically assignable to M. macrotarsus (sensu Rossi, 2005) are highly divergent from M. murina in cytochrome b sequence comparisons (>9%, uncorrected), and phylogenetic analyses of multilocus sequence data later showed that these species may not even be sister taxa ( Voss et al., 2014). Nevertheless, the morphological criteria by which specimens of M. macrotarsus and M. murina can be distinguished remain to be convincingly documented. Voss et al. (2019) discussed morphological comparisons between M. macrotarsus and M. waterhousei , another taxon formerly ranked as a subspecies of M. murina (see below).

Cabrera (1913) believed that Didelphys macrotarsus Wagner, 1842 , was preoccupied by D. macrotarsos Schreber, 1778 (a tarsier), and this opinion was endorsed by Creighton and Gardner (2008a). However, the one-letter difference in spelling is sufficient to prevent homonymy ( Rossi, 2005). Therefore, although Cabrera’s replacement name is available in the sense of the Code ( ICZN, 1999: Article 12.2.3), it is an objective junior synonym of Wagner’s macrotarsus and therefore invalid.