


18 AMERICAN MUSEUM NOVITATES NO. 3466 
TABLE 3 
Measurements (mm) and Weights (g) of Marmosops creightoni 
CBF UMMZ UMMZ UMMZ UMMZ UMMZ 
6552a 155999b 1560005 156001 1560025 1560035 
Sex male male male male female female 
HBL 132 127 140 129 120 114 
LT 177 153 162 173 150 174 
HF 20 18 20 19¢ 18¢ 18 
Ear 23 23 25 23 21 21 
CBL 35.6 33.3 35.5 35.0 32.7 32.6 
NB 4.8 4.4 4.8 4.9 4.2 4.4 
LIB ee 6.8 7.2 7.2 7.0 6.6 
ZB 17.2 16.8 — 16.8 16.4 15.7 
PL 21.2 19.7 — 20.3 19.3 19.2 
PB 10.1 9.6 — 10.1 9.7 9.3 
MTR 14.8 13.4 14.4 13.8 13.4 13.2 
LM 6.8 6.5 7.0 6.6 6.7 6.5 
M1-M3 5.7 5.6 6.1 5.7 5.8 5.6 
WM4 oie 2.1 2.3 2:2 2.0 2.0 
Weight 48 36 54 43 32 35 
aThe holotype. 
bParatype. 
cCRemeasured from fluid-preserved specimen. 
Bolivian specimens of Marmosops nocti- 
vagus Overlap broadly with M. creightoni in 
most measured dimensions, but they usually 
have dull reddish-brown (versus rich choco- 
late-brown) dorsal fur; pale-furred metapo- 
dials that do not contrast in color with the 
digits (versus dark-furred metapodials con- 
trasting with whitish digits); distinct supra- 
orbital beads that conceal the postorbital con- 
striction from dorsal view (versus supraor- 
bital beads absent or indistinct and postor- 
bital constriction visible dorsally); and 
smaller, conical or flask-shaped bullae (ver- 
sus bullae larger and hemispherical). In ad- 
dition, adult males of M. noctivagus have a 
pale scrotum with white fur and unpigmented 
skin (versus scrotum dark with brownish fur 
and mottled-grayish skin), and adult females 
have 5—1—5 = 11 mammae, of which the an- 
teriormost pair is pectoral (versus 4-1-4 = 
9 abdominal-inguinal teats). 
Marmosops ocellatus also overlaps broad- 
ly with M. creightoni in most measured di- 
mensions, but it has much paler grayish- 
brown (versus rich chocolate-brown) dorsal 
fur; pale-furred metapodials that do not con- 
trast in color with the digits (versus dark- 
furred metapodials contrasting with whitish 
digits); distinctly bi- and particolored tails, 
with the terminal one-third or more com- 
pletely pale (versus tail indistinctly bicolored 
and only the tip completely pale); a much 
narrower interorbital region (LIB = 5.5—6.3 
mm versus 6.6—7.2 mm); and proportionately 
wider zygomatic arches (ZB/CBL X 100 = 
53-54% versus 48-50%). In addition, most 
adult males of M. ocellatus lack a gular gland 
(versus gular gland weakly developed), and 
adult females have 6—1—6 = 13 mammae, of 
which the anteriormost two pairs are pectoral 
(versus 4—1—4 = 9 abdominal-inguinal mam- 
mae). 
Although we examined representative ma- 
terial of every species of Marmosops listed 
as valid in table 1, additional pairwise com- 
parisons are unnecessary because other cur- 
rently recognized species exhibit no special 
similarity with M. creightoni. Indeed, most 
extralimital (nonBolivian) species have strik- 
ingly divergent traits. Marmosops cracens, 
M. fuscatus, and M. incanus, for example, 
have uniformly narrow nasals with subpar- 
allel lateral margins (quite unlike the poste- 
riorly expanded nasals of Bolivian forms); 
M. pinheiroi has lacrimal foramina that are 
laterally exposed anterior to the orbit (the 
