Marmosa (Eomarmosa), Voss & Gutiérrez & Solari & Rossi & Jansa, 2014

Voss, Robert S., Gutiérrez, Eliécer E., Solari, Sergio, Rossi, Rogério V. & Jansa, Sharon A., 2014, Phylogenetic Relationships of Mouse Opossums (Didelphidae, Marmosa) with a Revised Subgeneric Classification and Notes on Sympatric Diversity, American Museum Novitates 2014 (3817), pp. 1-1 : 1-

Eomarmosa , new subgenus

TYPE SPECIES: Marmosa rubra Tate, 1931 .

CONTENTS: rubra Tate, 1931 .

DIAGNOSIS: Gular gland absent; manual claws small (not extending beyond fleshy apical pads of fingers); medial and lateral carpal tubercles present in large adult males (e.g., AMNH 71950); dorsal tail scales rhomboidal and arranged in predominantly spiral series; ventral prehensile surface of tail not densely fringed by long hairs. Postorbital processes absent, indistinct, or very small; palatine fenestrae absent; fenestra cochleae concealed; M2 preparacrista attaches to stylar cusp A.

COMPARISONS: Eomarmosa differs from other subgenera of Marmosa in petrosal and dental characters. Specifically, the fenestra cochleae of Eomarmosa is concealed within a sinus formed by the caudal and rostral tympanic processes of the petrosal, whereas the fenestra cochleae in other subgenera is normally exposed because the rostral and caudal tympanic processes of the petrosal are widely separated. Additionally, the preparacrista on M2 of Eomarmosa attaches to stylar cusp A (or to the corresponding anterolabial corner of the stylar shelf when a discrete cusp is missing), whereas the M2 preparacrista of other subgenera usually passes straight labially to terminate at or near stylar cusp B.

Other characters distinguish Eomarmosa from some, but not all, other congeners. For example, Eomarmosa differs from Exulomarmosa by its lack of a gular gland—consistently present as a hairless patch of (often greasy) skin in adult male specimens of the latter subge-nus—and by the spiral arrangement of its caudal scales (the arrangement of tail scales of Exulomarmosa usually includes at least some in annular series). Eomarmosa differs from members of the subgenus Marmosa by the presence of well-developed medial and lateral carpal tubercles in large adult males (sexually dimorphic carpal tubercles are consistently absent in Marmosa ). Eomarmosa has small manual claws, the tips of which do not extend distally beyond the fleshy apical pads of the fingers, whereas the manual claws of Micoureus are larger, stronger, and (unless blunted) usually extend slightly beyond the fleshy apical pads of the fingers. Lastly, Eomarmosa lacks the dense fringes of long silvery hairs that border the caudal prehensile surface in both species of Stegomarmosa .

ETYMOLOGY: From the ancient Greek ἕως (“dawn”), by metonymy, for the reddish fur of the single included species.

REMARKS: A detailed description of Marmosa (Eomarmosa) rubra was provided by Rossi et al. (2010), who also mapped the collection localities of all known specimens. Based on those data, the geographic range of M. rubra appears to be restricted to western Amazonia, where it is known to occur from southeastern Colombia to southeastern Peru ( Rossi et al., 2010: fig. 30). This taxon occurs sympatrically—but perhaps not syntopically—with members of the subgenera Marmosa and Micoureus , (e.g., at Boca Río Curaray, Departamento Loreto, Peru; Tate,