136 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 322 Fig. 53. Marmosops pinheiroi (based on AMNH 267345, a young adult male from Paracou, French Guiana), a small species that differs from M. creightoni (fig. 52) in several trenchant craniodental features including laterally exposed lacrimal foramina, absence <strong>of</strong> palatine vacuities, <strong>and</strong> presence <strong>of</strong> accessory cusps on C1.
2009 VOSS AND JANSA: DIDELPHID MARSUPIALS 137 contact on lateral braincase (no frontalsquamosal contact). Sagittal crest absent. Petrosal consistently exposed laterally through fenestra in parietal-squamosal suture in most species (fenestra polymorphically absent in M. incanus <strong>and</strong> M. noctivagus). Parietalmastoid contact present (interparietal does not contact squamosal). Maxillopalatine fenestrae present; palatine fenestrae present in some species (e.g., M. creightoni; fig. 52), but absent in others (e.g., M. pinheiroi; fig. 53); maxillary fenestrae absent; posterolateral palatal foramina small, not extending anteriorly lingual to M4 protocones; posterior palatal morphology conforms to Didelphis morphotype (with prominent lateral corners, the choanae constricted behind). Maxillary <strong>and</strong> alisphenoid not in contact on floor <strong>of</strong> orbit (separated by palatine). Transverse canal foramen present. Alisphenoid tympanic process small, <strong>of</strong>ten bluntly conical or laterally compressed (never smoothly globular), always with a welldeveloped anteromedial process enclosing the extracranial course <strong>of</strong> m<strong>and</strong>ibular nerve (secondary foramen ovale present), <strong>and</strong> not contacting rostral tympanic process <strong>of</strong> petrosal. Anterior limb <strong>of</strong> ectotympanic directly suspended from basicranium. Stapes triangular, with large obturator foramen. Fenestra cochleae exposed, not concealed by rostral <strong>and</strong> caudal tympanic processes <strong>of</strong> petrosal. Paroccipital process small, rounded, <strong>and</strong> adnate to petrosal. Dorsal margin <strong>of</strong> foramen magnum bordered by supraoccipital <strong>and</strong> exoccipitals, incisura occipitalis present. Two mental foramina usually present on lateral surface <strong>of</strong> each hemim<strong>and</strong>ible; angular process acute <strong>and</strong> strongly inflected. Unworn crowns <strong>of</strong> I2–I5 symmetrically rhomboidal (‘‘premolariform’’), with subequal anterior <strong>and</strong> posterior cutting edges, increasing in length (mesiodistal dimension) from I2 to I5. Upper canine (C1) alveolus in premaxillary-maxillary suture; C1 without accessory cusps in some species (e.g., M. creightoni; fig. 52), or with posterior accessory cusp (e.g., M. juninensis), or with anterior <strong>and</strong> posterior accessory cusps (e.g., M. pinheiroi; fig 53). First upper premolar (P1) smaller than posterior premolars but well formed <strong>and</strong> not vestigial; second <strong>and</strong> third upper premolars (P2 <strong>and</strong> P3) subequal in height; P3 with posterior cutting edge only; upper milk premolar (dP3) large <strong>and</strong> molariform. Molars strongly carnassialized (postmetacristae much longer than postprotocristae); relative widths usually M1 , M2 , M3 , M4; centrocrista strongly inflected labially on M1–M3; ect<strong>of</strong>lexus shallow or indistinct on M1, shallow but usually distinct on M2, <strong>and</strong> consistently deep on M3; anterolabial cingulum <strong>and</strong> preprotocrista discontinuous (anterior cingulum incomplete) on M3 in some species (e.g., M. noctivagus) but anterolabial cingulum continuous with preprotocrista (anterior cingulum complete) in others (e.g., M. parvidens); postprotocrista without carnassial notch. Last upper tooth to erupt is P3. Lower incisors (i1–i4) with distinct lingual cusps. Second lower premolar (p2) subequal in height to p3 in some species (e.g., M. incanus) but distinctly taller than p3 in others (e.g., M. impavidus); lower milk premolar (dp3) trigonid complete. Hypoconid labially salient on m3; hypoconulid twinned with entoconid on m1–m3; entoconid usually taller than hypoconulid on m1–m3. DISTRIBUTION: Species <strong>of</strong> Marmosops occur in tropical lowl<strong>and</strong> <strong>and</strong> montane moist forests from central Panama southward along the Andes <strong>and</strong> throughout Amazonia to eastern Bolivia <strong>and</strong> southeastern Brazil (see maps in Gardner <strong>and</strong> Creighton, 2008a). The genus is apparently unknown from Paraguay, Argentina, <strong>and</strong> Uruguay. See Mustrangi <strong>and</strong> Patton (1997) for verified specimen records based on modern revisionary research in southeastern Brazil, Patton et al. (2000) for the same in western Amazonia, Voss et al. (2001) for northeastern Amazonia, <strong>and</strong> Voss et al. (2004b) for Bolivia. Many other published geographic data purporting to represent records <strong>of</strong> Marmosops species (e.g., Anderson, 1997; Brown, 2004) are based on misidentified material (Voss et al., 2004b). REMARKS: The monophyly <strong>of</strong> Marmosops is uniformly strongly supported by parsimony, likelihood, <strong>and</strong> Bayesian analyses <strong>of</strong> IRBP (fig. 28), DMP1 (fig. 29), BRCA1 (fig. 31), vWF (fig. 32), <strong>and</strong> concatenated sequence data from five genes (fig. 33). The genus is also recovered with strong support by parsimony <strong>and</strong> Bayesian analyses <strong>of</strong>
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