Marmosini Hershkovitz, 1992

Voss, RS & Jansa, SA, 2009, Phylogenetic Relationships And Classification Of Didelphid Marsupials, An Extant Radiation Of New World Metatherian Mammals, Bulletin of the American Museum of Natural History 2009 (322), pp. 1-177 : 100-101

Tribe Marmosini Hershkovitz, 1992

CONTENTS: Marmosa , Monodelphis , † Thylatheridium , and Tlacuatzin .

DIAGNOSIS: Marmosines can be distinguished from other members of the subfamily Didelphinae by lacking a pouch (present in all Didelphini ), by lacking an anteromedial bullar process spanning the transverse canal foramen (present in Metachirini and most Thylamyini ), by lacking a fenestra in the squamosal-parietal suture (present in most Thylamyini ), and by having the supraoccipital form part of the dorsal margin of the foramen magnum (absent in adult Metachirini and most adult Didelphini ).

REMARKS: The monophyly of Marmosini as construed herein is strongly supported by all analyses of BRCA1 (fig. 31), vWF (fig. 32), concatenated sequence data from five genes (fig. 33), and our combined (nonmolecular + molecular) dataset excluding Chacodelphys (fig. 35). However, no morphological trait optimizes as an unambiguous synapomorphy of this molecularly robust clade. Instead, all of the diagnostic features listed above appear to be plesiomorphic within the subfamily Didelphinae .

Although the name Marmosini was used by Reig et al. (1985, 1987) it was not accompanied by an explicit statement of taxonomically differentiating characters. To the best of our knowledge, the first familygroup name based on Marmosa is technically available from Hershkovitz (1992b). An alternative name for this clade is Monodelphini , which McKenna and Bell (1997) attributed to Talice et al. (1961). However, Talice et al. did not mention any characters purported to differentiate Monodelphini from other didelphids, so their name is unavailable ( ICZN, 1999: Article 13). To the best of our knowledge, the first familygroup name based on Monodelphis is also available from Hershkovitz (1992b). As first revisors in the sense of the Code ( ICZN, 1999: Article 24), we select Marmosini Hershkovitz, 1992 , to have precedence over Monodelphini Hershkovitz, 1992 .

Our reluctance to recognize any subtribal distinction between Marmosa and Monodelphis is based on the uncertain position of Tlacuatzin , which is not convincingly resolved despite the large amount of data at hand (.2000 parsimony-informative characters; table 12). In the event that a sister-group relationship between Marmosa and Tlacuatzin (weakly indicated by supermatrix analyses; figs. 33–36) were strongly supported by some future dataset, it would then make sense to recognize one subtribe (e.g., Marmosina) for those taxa and another (Monodelphina) for Monodelphis and † Thylatheridium . Although it seems indisputable that Monodelphis and † Thylatheridium are closely related ( Goin and Rey, 1997), we note that this hypothesis has yet to be tested analytically, nor is it certainly known whether or not these taxa are reciprocally monophyletic.25