Description

DESCRIPTION: Body pelage grayish brown (near Fuscous or Hair Brown) middorsally, sometimes indistinctly paler laterally, and about 7 – 9 mm long at midback; ventral pelage superficially whitish, but hairs of throat, chest, and abdomen uniformly gray based in most specimens (a few have patches or narrow streaks of self-white fur on the throat, chest, groin, or along the insides of the thighs; e. g., AMNH 144832, USNM 370037). Manus covered dorsally with uniformly pale hairs (the metacarpals not contrasting sharply in color with the digits); lateral carpal tubercles bladelike in all examined adult males. Mammae 3 – 1 – 3 = 7 in all examined females with visible teats. Tail longer than combined length of head and body (mean LT / HBL × 100 = 120 %); dorsal caudal surface dark, but indistinctly paler distally in some specimens; ventral caudal surface distinctly paler than dorsal surface. Nasal bones long (extending well behind the lacrimals) and uniformly narrow, without conspicuous lateral expansion at the maxillary-frontal suture. Interorbital region broad, with rounded supraorbital margins in females and young adult males, but relatively narrower and tending to develop squared supraorbital margins in large adult males; postorbital processes absent or indistinct. Lacrimal foramina usually visible in lateral view; zygomatic process of the squamosal broadly overlapped dorsally by the jugal. Palatine fenestrae present or absent (when present, palatine fenestrae usually consist of several small irregular perforations, but in a few specimens they are large). Dorsolateral margin of ethmoid foramen usually formed by the orbitosphenoid. Upper canine (C 1) sexually dimorphic (taller and unicuspid in males, shorter and with one or two accessory cusps in females). 5 Upper third molar (M 3) anterolabial cingulum discontinuous with preprotocrista (anterior cingulum incomplete). Lower canine (c 1) sexually dimorphic (erect, without accessory cusps, and taller than p 1 in males versus procumbent, with posterior accessory cusp, and subequal in height to p 1 in females); c 1 anterolingual accessory cusp usually absent in both sexes. Entoconid of m 1 apparently subequal to m 2 paraconid (but few specimens with unworn molars examined for this trait); unworn m 4 talonid with three distinct cusps. COMPARISONS: Marmosops carri is externally similar to M. fuscatus (with which it was formerly synonymized; see Remarks) but has somewhat paler dorsal fur, averages larger in all external measurements (tables 5, 6), and has a relatively longer tail (e. g., LT / HBL × 100 = 122 % 5 All examined females have posterior accessory C 1 cusps, and insular populations (from Trinidad and Tobago) usually also have small anterior accessory cusps (e. g., AMNH 5921, 234951, 234954, 234956, 259979). By contrast, females from mainland populations usually lack anterior accessory cusps on C 1 (e. g., AMNH 144832; USNM 370030, 517256). in male carri versus 110 % in male fuscatus). Marmosops carri averages larger than M. fuscatus in all measured craniodental dimensions (except nasal breadth, NB) but especially in three dental dimensions (MTR, LM, M 1 – 3) that exhibit nonoverlapping variation. In other (qualitative) aspects of craniodental morphology the two species cannot be consistently distinguished, although there are modal differences in some characters. For example, the dorsolat- eral margin of the ethmoid foramen is usually formed by the orbitosphenoid in M. carri, whereas this foramen is bordered dorsolaterally by the frontal in M. fuscatus. Handley and Gordon (1979) implied that carri and fuscatus (which they regarded as no more than subspecifically distinct) differ in nasal morphologythe nasals were said to be more expanded posteriorly in fuscatus than in carri — but we did not observe a consistent taxonomic difference in our comparisons of representative specimens of these taxa. Marmosops carri is substantially larger than M. handleyi in all external measurements, especially in three dimensions (HBL, LT, and Ear) that exhibit nonoverlapping variation in samesex sample comparisons. In qualitative external comparisons, these species principally differ in coloration: whereas M. carri has grayish-brown dorsal body pelage and entirely white forefeet, M. handleyi has dark-brown dorsal pelage and dark metacarpals that contrast in color with its whitish manual digits. Skulls and dentitions of M. carri are considerably larger than those of M. handleyi, exhibiting nonoverlapping variation in same-sex comparisons of eight dimensions (CBL, ZB, PL, PB, MTR, LM, M 1 – 3, and WM 3). Overall, the skull of M. carri is more heavily built (especially in males) by comparison with the more delicate cranial construction of M. handleyi. In qualitative aspects of craniodental morphology, M. carri principally differs from M. handleyi by its uniformly narrow nasals (the nasals are posteriorly expanded in M. handleyi); unicuspid male C 1 (this tooth has a posterior accessory cusp in male M. handleyi), and absence of a lingual accessory cusp on c 1 in most specimens of both sexes (a lingual accessory cusp on c 1 is present in both sexes of M. handleyi). Marmosops carri is much larger than M. invictus, with no overlapping variation in same-sex comparisons of most measured dimensions. These species also differ strikingly in dorsal pelage coloration (much paler in M. carri than in M. invictus), coloration of the forefeet (entirely whitish in M. carri, whereas the metacarpals are dark in M. invictus), and tail markings (the tail is much more distinctly bicolored in M. carri). Qualitative craniodental comparisons reveal several additional contrasting differences. Among others, M. carri has uniformly narrow nasals, whereas the nasals are laterally expanded near the maxillary-frontal suture in M. invictus; at least the ventral lacrimal foramen is consistently visible in lateral view in M. carri, whereas this foramen is concealed inside the orbit in M. invictus; palatine fenestrae are often present in M. carri, whereas palatine perforations are consistently absent in M. invictus); c 1 is a tall unicuspid tooth in male M. carri, whereas this tooth is short and premolariform in male M. invictus; and the m 1 entoconid is subequal in height to the adjacent m 2 paraconid in M. carri, whereas the m 1 entoconid is shorter than the m 2 paraconid in M. invictus.

Common Names

No common names available.

Taxonomic Hierarchy

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Didelphimorphia

Family: Didelphidae

Genus: Marmosops

Species: Marmosops carri (Allen & Chapman, 1897)