phylogenetic relationships and classification of didelphid marsupials ...

138 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 322
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).
Thylamys Gray, 1843
Figure 54
CONTENTS: cinderella Thomas, 1902 (including
sponsorius Thomas, 1921); elegans
Waterhouse, 1839 (including coquimbensis
Tate, 1931; and soricinus Philippi, 1894);
karimii Petter, 1968; macrurus Olfers, 1818
(including griseus Desmarest, 1827); pallidior
Thomas, 1902; pusillus Desmarest, 1804
(including bruchi Thomas, 1921; citellus
Thomas, 1912; nanus Olfers, 1818; and verax
Thomas, 1921); tatei Handley, 1957; velutinus
Wagner, 1842 (including pimelurus Reinhardt,
1851); and venustus Thomas, 1902
(including janetta Thomas, 1926).
MORPHOLOGICAL DESCRIPTION: Combined
length of adult head and body ca. 75–
140 mm; adult weight ca. 10–65 g. Rhinarium
with two ventrolateral grooves on each
side of median sulcus in most examined
species (but T. pallidior has only a single
ventrolateral groove on each side); dark
circumocular mask present; pale supraocular
spot absent; dark midrostral stripe absent;
throat gland present in fully adult males, and
apparently also in adult females of some
species (Carmignotto and Monfort, 2006).
Dorsal pelage usually grayish and distinctly
darker middorally than laterally (‘‘tricolored’’),
but dorsal fur brownish and without
conspicuous patterning in T. karimii and T.
velutinus (Carmignotto and Monfort, 2006);
dorsal hair bases dark gray; dorsal guard
hairs short and inconspicuous; ventral fur
self-white in some species (e.g., T. pusillus),
wholly or partly gray-based whitish or
yellowish in others (e.g., T. venustus). Manus
mesaxonic (dIII . dIV); manual claws about
as long as fleshy apical pads in most species
(but claws extend well beyond apical pads in
T. karimii and T. velutinus; Carmignotto and
Monfort, 2006); dermatoglyph-bearing manual
plantar pads present in most species;
central palmar epithelium densely covered
with small convex tubercles; carpal tubercles
absent in both sexes. Pedal digits unwebbed;
dIV longer than other pedal digits; plantar
surface of heel coarsely furred. Pouch absent;
mammae varying among species from 4–1–4
5 9 (in T. karimii; Carmignotto and Monfort,
2006) to 7–1–7 5 15 (in T. elegans; Tate,
1933), including ‘‘pectoral’’ teats (when the
total number of mammae $ 11); cloaca
present. Tail longer than combined length
of head and body in most species (except in
T. karimii and T. velutinus; Carmignotto and
Monfort, 2006); apparently always incrassate
(but quantity of stored fat may vary seasonally);
furred only at base (to about the same
extent dorsally as ventrally); unfurred caudal
integument bicolored (dark above, pale
below) in most species and parti-colored in
some (T. macrurus has an all-white tail tip);
tail scales in annular series, each scale with
three subequal bristlelike hairs emerging
from distal margin; ventral caudal surface
modified for prehension distally (with naked
median groove and apical pad bearing
dermatoglyphs) in most species, but ventral
prehensile surface reduced or absent in T.
karimii and T. velutinus (Carmignotto and
Monfort, 2006).
Premaxillary rostral process absent. Nasals
long, extending anteriorly above or beyond
I1 (concealing nasal orifice in dorsal view),
and uniformly narrow (with subparallel lateral
margins) in most specimens. Maxillary turbinals
elaborately branched. Two lacrimal