phylogenetic relationships and classification of didelphid marsupials ...

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126 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 322 elsewhere in northern Argentina, eastern Bolivia, western Paraguay, and southwestern Brazil, it would be reasonable to expect that the genus is more widely distributed. REMARKS: In the absence of undamaged cranial material, we are unable to provide an illustration for this genus. However, photographs of two imperfect skulls were published by Voss et al. (2004a: fig. 2) and Teta et al. (2006: fig. 2). The problematic relationships of this genus were discussed at length by Voss et al. (2004a) and seem unlikely to be resolved definitively in the absence of nuclear gene sequence data. As discussed above, the tribal membership of Chacodelphys is most compellingly supported by Bayesian analysis of a dataset that combines nonmolecular characters with nuclear-gene sequence data (fig. 36), but it is consistent with subjective assessments of similarity based on integumental and craniodental traits (e.g., by Tate, 1933). Although separate analyses of nonmolecular character data suggest that this genus may be more closely related to Thylamys and Lestodelphys than to other thylamyines (fig. 27), it seems premature to formalize such weakly supported results by subtribal nomenclature. Cryptonanus Voss et al., 2005 Figure 49 CONTENTS: agricolai Moojen, 1943; chacoensis Tate, 1931; guahybae Tate, 1931; ignitus Díaz et al., 2002; and unduaviensis Tate, 1931. MORPHOLOGICAL DESCRIPTION: Combined length of adult head and body ca. 80– 120 mm; adult weight ca. 15–40 g. Ventral margin of rhinarium with two shallow grooves on each side of median sulcus; dark circumocular mask present; pale supraocular spot absent; dark midrostral stripe absent; gular gland present in adult males. Dorsal body pelage unpatterned, usually grayish or reddish brown; dorsal fur gray based; dorsal guard hairs very short and inconspicuous; ventral fur gray based or self-colored (varying among species). Manus paraxonic (dIII 5 dIV); manual claws shorter than fleshy apical pads of digits; dermatoglyph-bearing manual plantar pads present; central palmar surface of manus sparsely tubercular (neither smooth nor densely covered with convex tubercles); lateral carpal tubercles present in adult males. Pedal digits unwebbed; dIV longer than other pedal digits; plantar epithelium of heel naked. Pouch absent; mammae 4–1–4 5 9 (all abdominal-inguinal) to 7–1–7 5 15 (with pectoral teats); cloaca present. Tail longer than combined length of head and body, slender and muscular (not incrassate); body pelage not extending more than a few mm onto tail base; unfurred caudal integument more or less bicolored (dark above, paler below) in most specimens; caudal scales in distinctly annular series, each scale with three subequal bristlelike hairs emerging from distal margin; ventral caudal surface modified for prehension distally, with apical pad bearing dermatoglyphs. Rostral process of premaxillae absent. Nasals long, extending anteriorly beyond I1 (concealing nasal orifice from dorsal view), and conspicuously widened posteriorly near maxillary-frontal suture. Maxillary turbinals large and elaborately branched. Two lacrimal foramina laterally exposed on each side on or just anterior to orbital margin. Supraorbital margins rounded, without beads or processes (a few old individuals have incipient postorbital processes); distinct interorbital and postorbital constrictions usually present in juveniles and young adults. Left and right frontals and parietals separated by persistent median sutures. Parietal and alisphenoid in contact on lateral braincase (no squamosalfrontal contact). Sagittal crest absent. Petrosal laterally exposed through fenestra in parietal-squamosal suture. Parietal-mastoid contact present (interparietal does not contact squamosal). Maxillopalatine fenestrae large; palatine fenestrae present; maxillary fenestrae absent; posterolateral palatal foramina small, not extending lingual to M4 protocones; posterior palate conforms to Didelphis morphotype (with prominent lateral corners, the internal choanae abruptly constricted behind). Maxillary and alisphenoid not in contact on orbital floor (separated by palatine). Transverse canal foramen present. Alisphenoid tympanic process smoothly globular, without anteromedial process or posteromedial lamina enclosing extracranial course of mandib-
2009 VOSS AND JANSA: DIDELPHID MARSUPIALS 127 Fig. 49. Cryptonanus unduaviensis (based on AMNH 209152, an adult female from the Río Baures, Beni, Bolivia).
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PHYLOGENETIC RELATIONSHIPS AND CLAS
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CONTENTS Abstract .................
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ABSTRACT This report summarizes a d
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