Marmosops Matschie, 1916

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: 134-138

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Marmosops Matschie, 1916
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Marmosops Matschie, 1916   Figures 52, 53

CONTENTS: bishopi Pine, 1981; cracens Handley and Gordon, 1979; creightoni Voss et al., 2004   ; fuscatus Thomas, 1896   (including carri J.A. Allen and Chapman, 1897; and perfuscus Thomas, 1924); handleyi Pine, 1981; impavidus Tschudi, 1845   (including caucae Thomas, 1900; celicae Anthony, 1922; madescens Osgood, 1913; oroensis Anthony, 1922; sobrinus Thomas, 1913; and ucayalensis Tate, 1931); incanus Lund, 1840   (including bahiensis Tate, 1931; and scapulatus Burmeister, 1856); invictus Goldman, 1912; juninensis Tate, 1931   ; neblina Gardner, 1990; noctivagus Tschudi, 1844   (including albiventris Tate, 1931   ; collega Thomas, 1920; dorothea Thomas, 1911; keaysi J.A. Allen, 1900; leucastrus Thomas, 1927; lugendus Thomas, 1927; neglectus Osgood, 1915; politus Cabrera, 1913; purui Miller, 1913; stollei Miranda-Ribeiro, 1936; and yungasensis Tate, 1931); ocellatus Tate, 1931   ; parvidens Tate, 1931   ; paulensis Tate, 1931; and pinheiroi Pine, 1981   (including woodalli Pine, 1981).

MORPHOLOGICAL DESCRIPTION: Combined length of adult head and body ca. 90– 195 mm; adult weight ca. 20–140 g. Rhinarium with two ventrolateral grooves on each side of median sulcus; dark circumocular mask present; pale supraocular spot absent; dark midrostral stripe absent; throat gland consistently present in adult males of some species (e.g., M. incanus   , M. noctivagus   ) but apparently absent in others (e.g., M. impavidus   , M. parvidens   ). Dorsal pelage unpatterned, usually some shade of dull grayish brown, but distinctly reddish or grayish in some species; dorsal hair bases always dark gray; dorsal guard hairs short and inconspicuous; ventral fur self-colored (whitish, buffy, or brown) or entirely or partially gray based. Manus mesaxonic (dIII. dIV); manual claws small, shorter than fleshy apical pads of digits; dermatoglyph-bearing manual plan- tar pads present; central palmar epithelium smooth or sparsely tuberculate; lateral carpal tubercles externally conspicuous on wrists of large adult males; medial carpal tubercles absent in both sexes. Pedal digits unwebbed; dIV longer than other pedal digits; plantar surface of heel macroscopically naked (a microscopic pelage of very short hairs, not coarse fur, is usually present). Pouch absent; mammae varying among examined species from 3–1–3 5 7 to 7–1–7 5 15, anteriormost pairs ‘‘pectoral’’ when mammae $ 11; cloaca present. Tail longer than combined length of head and body, slender and muscular (not incrassate), and macroscopically naked (without a conspicuously furred base); naked caudal integument uniformly dark (usually grayish), bicolored (dark above, pale below), or parti-colored (dark distally, paler distally); caudal scales in spiral series, each scale with three bristlelike hairs emerging from caudal margin; median hair of each caudal-scale triplet usually much thicker and darker than lateral hairs; ventral caudal surface modified for prehension distally (with naked median groove and apical pad bearing dermatoglyphs).

Premaxillary rostral process long and well developed in some species (e.g., M. parvidens   , M. pinheiroi   ) but short in others (e.g., M. noctivagus   ) and apparently absent in some ( M. incanus   ). Nasals long, extending anteriorly beyond I1 (concealing nasal orifice in dorsal view), and conspicuously widened posteriorly near maxillary-frontal suture except in M. incanus   (which has narrow, more or less parallel-sided nasals). Maxillary turbinals (viewed through nasal orifice) elaborately branched. Lacrimal foramina, usually two on each side, concealed from lateral view inside orbit (e.g., in M. parvidens   ) or exposed on orbital margin (e.g., in M. pinheiroi   ). Interorbital region without abrupt constrictions; supraorbital margins rounded in some species (e.g., M. parvidens   ), beaded in others (e.g., M. noctivagus   ); postorbital processes usually absent except in old males of some species (e.g., M. impavidus   32). Left and right frontals and parietals separated by persistent median sutures. Parietal and alisphenoid in

32 Postorbital processes in this species are best developed in

AMNH 272760.

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   and 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 and alisphenoid not in contact on floor of orbit (separated by palatine). Transverse canal foramen present. Alisphenoid tympanic process small, often bluntly conical or laterally compressed (never smoothly globular), always with a welldeveloped anteromedial process enclosing the extracranial course of mandibular nerve (secondary foramen ovale present), and not contacting rostral tympanic process of petrosal. Anterior limb of ectotympanic directly suspended from basicranium. Stapes triangular, with large obturator foramen. Fenestra cochleae exposed, not concealed by rostral and caudal tympanic processes of petrosal. Paroccipital process small, rounded, and adnate to petrosal. Dorsal margin of foramen magnum bordered by supraoccipital and exoccipitals, incisura occipitalis present.

Two mental foramina usually present on lateral surface of each hemimandible; angular process acute and strongly inflected.

Unworn crowns of I2–I5 symmetrically rhomboidal (‘‘premolariform’’), with subequal anterior and 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 and posterior accessory cusps (e.g., M. pinheiroi   ; fig 53). First upper premolar (P1) smaller than posterior premolars but well formed and not vestigial; second and third upper premolars (P2 and P3) subequal in height; P3 with posterior cutting edge only; upper milk premolar (dP3) large and molariform. Molars strongly carnassialized (postmetacristae much longer than postprotocristae); relative widths usually M1, M2, M3, M4; centrocrista strongly inflected labially on M1–M3; ectoflexus shallow or indistinct on M1, shallow but usually distinct on M2, and consistently deep on M3; anterolabial cingulum and preprotocrista discontinuous (anterior cingulum incomplete) on M 3 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 p 3 in some species (e.g., M. incanus   ) but distinctly taller than p 3 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 of Marmosops   occur in tropical lowland and montane moist forests from central Panama southward along the Andes and throughout Amazonia to eastern Bolivia and southeastern Brazil (see maps in Gardner and Creighton, 2008a). The genus is apparently unknown from Paraguay, Argentina, and Uruguay. See Mustrangi and 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, and Voss et al. (2004b) for Bolivia. Many other published geographic data purporting to represent records of Marmosops species   (e.g., Anderson, 1997; Brown, 2004) are based on misidentified material ( Voss et al., 2004b).

REMARKS: The monophyly of Marmosops   is uniformly strongly supported by parsimony, likelihood, and Bayesian analyses of IRBP (fig. 28), DMP1 (fig. 29), BRCA1 (fig. 31), vWF (fig. 32), and concatenated sequence data from five genes (fig. 33). The genus is also recovered with strong support by parsimony and Bayesian analyses of combined datasets that include nonmolecular and molecular characters (figs. 35, 36), and by Bayesian analyses of nonmolecular characters (fig. 27) and RAG1 sequences (fig. 30). Spirally arranged caudal scales, the petiolate morphology of the central hair in each caudal-scale triplet, the presence of a rostral process of the premaxillae, and unique deletions at the DMP1 and BRCA1 loci optimize as unambiguous generic synapomorphies (appendix 5; figs. 29, 31). As noted elsewhere, Kirsch and Palma’s (1995) suggestion that Marmosops   is paraphyletic was based on misidentified voucher material ( Voss and Jansa, 2003: 57).

Discrepancies between our species-level synonymies for Marmosops   and those in Gardner (2005) are explained by Voss et al. (2004b). Few of the currently recognized species have received critical revisionary attention, and it seems likely that several widespread taxa (e.g., M. fuscatus   , M. noctivagus   , and M. impavidus   ) will prove to be composite. For regional revisions of Marmosops   see Mustrangi and Patton (1997), Patton et al. (2000), and Voss et al. (2001, 2004b).