phylogenetic relationships and classification of didelphid marsupials ...

2009 VOSS AND JANSA: DIDELPHID MARSUPIALS 131
p3; lower milk premolar (dp3) trigonid
incomplete (unicuspid in the few specimens
we were able to score for this trait).
Hypoconid labially salient on m3; hypoconulid
twinned with entoconid on m1–m3;
entoconid taller than hypoconulid on m1–m3.
DISTRIBUTION: Species of Gracilinanus
occur in tropical and subtropical moist
forests in lowland and montane landscapes
(to at least 3350 m; Voss et al., 2004b: table
12) from northern Venezuela to Bolivia,
Paraguay, southeastern Brazil, northeastern
Argentina, and northern Uruguay (D’Elía
and Martínez, 2006; Teta et al., 2007;
Creighton and Gardner, 2008a). Apparently,
only one Argentinian record and two Uruguayan
records of Gracilinanus are valid,
the remaining published localities for this
genus from both countries having been based
on specimens of Cryptonanus (see Voss et al.,
2005; D’Elía and Martínez, 2006; Teta et al.,
2007). Gracilinanus is said not to occur in
central Amazonia (Patton and Costa, 2003),
but the species to be expected there (G.
emiliae) is difficult to collect and this
distributional hiatus is perhaps an artifact
of inadequate faunal sampling. 30
REMARKS: The contents of this genus have
changed significantly in the years since it was
first described by Gardner and Creighton
(1989), principally by removal of distantly
related forms to new genera (see Voss et al.,
2005: table 1). With the exception of Gracilinanus
microtarsus and G. agilis, species of
this genus are not common in museum
collections, and geographic distributions remain
poorly documented. In addition, current
species concepts will doubtless change as
more information becomes available. For
example, molecular data (summarized by
Costa et al., 2003) suggest the presence of
an undescribed, morphologically cryptic species
among the material currently identified
as G. microtarsus; the geographic distribution
of material currently identified as G. emiliae
is improbably broad; and some specimens
from northern Colombia and eastern Peru do
30 All of the central Amazonian records of Gracilinanus
emiliae mapped by Hershkovitz (1992b: fig. 1) and Brown
(2004: fig. 20) are either based on misidentified material or
specimens that have yet to be examined for reliably diagnostic
traits (Voss et al., 2001: 29–30).
not resemble any currently recognized taxa.
Therefore, the species-level diversity of Gracilinanus
seems certain to increase with future
revisionary research.
The monophyly of Gracilinanus in its
currently restricted sense is strongly supported
by parsimony, likelihood, and Bayesian
analyses of RAG1 (fig. 30), BRCA1 (fig. 31),
vWF (fig. 32), concatenated sequence data
from five genes (fig. 33), and combined
datasets that include both nonmolecular
and molecular characters (figs. 35, 36); it is
also moderately supported by parsimony and
likelihood analyses of IRBP (fig. 28). We
have no plausible explanation as to why
analyses of DMP1 strongly support the
conflicting hypothesis that G. emiliae is the
sister taxon of Cryptonanus (fig. 29). Although
Gracilinanus is recovered as a clade
by parsimony analysis of nonmolecular data
(fig. 27), only two morphological traits optimize
as unambiguous generic synapomorphies
(appendix 5).
Lestodelphys Tate, 1934
Figure 51
CONTENTS: halli Thomas, 1921.
MORPHOLOGICAL DESCRIPTION: Combined
length of adult head and body probably ca.
120–160 mm; adult weight probably ca. 60–
100 g (very few reliably measured specimens
accompanied by weights are available). Rhinarium
with one ventrolateral groove on each
side of median sulcus; dark circumocular
mask present; pale supraocular spot absent;
dark midrostral stripe absent; throat gland
present in adult males. Dorsal pelage tricolored
(distinctly darker middorsally than on
flanks); dorsal underfur dark gray; dorsal
guard hairs short and inconspicuous; ventral
fur self-white from chin to anus. Manus
mesaxonic (dIII . dIV); manual claws much
longer than fleshy apical pads of digits;
dermatoglyph-bearing manual plantar pads
present; central palmar epithelium densely
tuberculate; carpal tubercles absent. Pedal
digits unwebbed; dIII longer than other pedal
digits; plantar surface of heel coarsely furred.
Pouch absent; mammae 8–1–8 5 17 or 9–1–9
5 19, of which the anteriormost teats are
‘‘pectoral’’; cloaca present. Tail shorter than
combined length of head and body, incrassate,