phylogenetic relationships and classification of didelphid marsupials ...

116 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 322
seems probable that at least some of the
many putative synonyms of Chironectes
minimus will be found to represent valid taxa
in future analyses of morphological and/or
molecular data.
Didelphis Linnaeus, 1758
Figure 46
CONTENTS: albiventris Lund, 1840 (including
bonariensis Marelli, 1930; dennleri Marelli,
1930; lechei Ihering, 1892; leucotis
Wagner, 1847; paraguayensis J.A. Allen,
1902; poecilotis Wagner, 1842; and poecilonota
Schinz, 1844); aurita Wied-Neuweid,
1826 (including koseritzi Ihering, 1892; longipilis
Miranda-Ribeiro, 1935; and melanoidis
Miranda-Ribeiro, 1935); imperfecta Mondolfi
and Pérez-Hernández, 1984; marsupialis
Linnaeus, 1758 (including battyi Thomas,
1902; cancrivora Gmelin, 1788; caucae J.A.
Allen, 1900; colombica J.A. Allen, 1900;
etensis J.A. Allen, 1902; insularis J.A. Allen,
1902; karkinophaga Zimmermann, 1780; particeps
Goldman, 1917; richmondi J.A. Allen,
1901; and tabascensis J.A. Allen, 1901);
pernigra J.A. Allen, 1900 (including andina
J.A. Allen, 1902; and meridensis J.A. Allen,
1902); and virginiana Kerr, 1792 (including
boreoamericana J.A. Allen, 1902; breviceps
Bennett, 1833; californica Bennett, 1833;
cozumelae Merriam, 1901; illinensium Link,
1795; pigra Bangs, 1898; pilosissima Link,
1795; pruinosa Wagner, 1843; texensis J.A.
Allen, 1901; woapink Barton, 1806; and
yucatanensis J.A. Allen, 1901).
MORPHOLOGICAL DESCRIPTION: Combined
length of adult head and body 310–495 mm;
adult weight 600–5100 g. Rhinarium with
one ventrolateral groove on each side of
median sulcus; dark circumocular mask
indistinct in some species (D. aurita, D.
marsupialis, D. virginiana) but distinct in
others (D. albiventris, D. imperfecta, D.
pernigra); pale supraocular spot absent; dark
midrostral stripe absent; throat gland absent.
Dorsal pelage unpatterned; dorsal underfur
white; dorsal guard hairs long, coarse and
conspicuous, giving the pelage a distinctively
shaggy appearance; ventral fur pale (usually
whitish) tipped with black. Manus mesaxonic
(dIII . dIV); manual claws usually longer
than fleshy apical pads of digits; dermato-
glyph-bearing manual plantar pads present;
central palmar epithelium smooth or sparsely
tuberculate; carpal tubercles absent. Pedal
digits unwebbed; dIV slightly longer than
other pedal digits in some species (e.g., D.
marsupialis) or dII, dIII, and dIV subequal
(e.g., in D. albiventris and D. virginiana);
plantar surface of heel naked. Pouch well
developed, opening anteriorly; mammae normally
3–1–3 5 7 to 6–1–6 5 13 or more 29 ;
cloaca present. Tail slightly longer than
combined length of head and body, slender
and muscular (not incrassate); basal 1/6 to
1/4 densely furred (covered with body pelage);
naked caudal integument blackish proximally
and abruptly whitish distally; caudal scales in
spiral series, each scale usually with three
subequal bristlelike hairs emerging from
distal margin; ventral caudal surface variably
modified for prehension distally (prehensile
modifications are more strongly developed in
D. auritus and D. marsupialis than in the other
species), but dermatoglyph-bearing apical
pad consistently present.
Premaxillary rostral process absent. Nasals
short, not produced anteriorly above I1
(exposing nasal orifice in dorsal view), and
conspicuously widened posteriorly near maxillary-frontal
suture. Maxillary turbinals
elaborately branched. Lacrimal foramina
one or two on each side, exposed laterally
on orbital margin or on face just anterior to
orbit. Postorbital processes bluntly pyramidal,
maximally developed in old adults. Left
and right frontals co-ossified (midfrontal
suture incomplete or absent), but left and
right parietals separated by persistent midparietal
suture. Parietal and alisphenoid in
contact on lateral braincase (no frontalsquamosal
contact). Sagittal crest large, well
developed, and extending onto frontals.
Petrosal not exposed laterally through fenestra
in squamosal-parietal suture (fenestra
absent). Parietal-mastoid contact absent (interparietal
narrowly contacts squamosal).
Maxillopalatine and palatine fenestrae
present; maxillary fenestrae absent; posterolateral
palatal foramina not extending anteriorly
lingual to M4 protocones; posterior
29 Occasional records of Didelphis virginiana with up to 17
pouch young (cited by Hamilton, 1958) suggest that teat counts
in this species may sometimes exceed 6–1–6 5 13.