28 AMERICAN MUSEUM NOVITATES NO. 3466 
TABLE 9 
Measurements (mm) and Weights (g) of Lowland Specimens of Marmosops noctivagus 
from Peru and Bolivia 



Peru: Junina Bolivia: La Paz and Pando 


AMNH AMNH AMNH AMNH USNM AMNH AMNH AMNH 
230005 230010 230013 230012 579250 262404 262402 262403 
Sex female female female male female female male male 
HBL 141 124 {140]> 126 141 126 120 123 
LT 170 156 165 189 173 164 184 167 
HF 19 17 [19]> 21 19 20 20 20 
Ear 25 20 18 24 23 20 22 21 
CBL — 34.8 36.3 38.7 35.9 34.7 36.1 35.0 
NB 4.5 4.2 4.1 4.0 4.0 3.8 3.9 3.8 
LIB 6.6 6.3 6.2 6.7 6.5 6.2 6.1 6.0 
ZB 18.2 17.1 18.4 18.8 19.3 18.3 18.3 18.3 
PL 20.5 20.0 21.0 22.4 21.0 20.2 21.2 20.2 
PB 11.5 11.0 11.0 11.2 11.3 11.5 10.8 11.0 
MTR 15.1 15.0 15.0 16.4 15.2 15.1 15.6 14.8 
LM 75 75 7.4 7.6 7.8 74 7.4 7.4 
MI-M3 6.4 6.4 6.4 6.5 6.7 6.3 6.4 6.4 
WM4 2.9 2.6 2.7 2.7 2.9 2.8 2.6 2.6 
Weight 48 —_ 59 58 42 37 36 35 

aThe external measurements of this series were taken by several different individuals, some of whom were inexperienced under- 
graduate students, and exhibit more variation than is usual in otherwise homogeneous samples of small didelphids. 
bTwo measurements recorded by the collector of this specimen are anatomically impossible. We assume that the true value for 
TL was 305 rather than the recorded value of 205 mm (resulting in a computed value for HBL of 140 versus 40 mm), and that the 
true value for HF was 19 rather than the recorded value of 9 mm. 
large specimens (table 9) with dull reddish- 
brown dorsal fur, mostly self-whitish ventral 
fur, pale-furred metapodials that do not con- 
trast abruptly in color with the digits, and 
more-or-less unicolored (all-dark) tails. All 
of the adult males we examined have well- 
developed gular glands, knobby (not blade- 
like) lateral carpal tubercles, and pale scro- 
tums with whitish fur and unpigmented skin. 
Although we have not seen fluid-preserved 
parous adult females from Bolivia, two Pe- 
ruvian specimens (AMNH 272782, 273051) 
each have 5—1—5 = 11 mammae, of which 
the anteriormost pair is pectoral. Associated 
skulls have distinct supraorbital beads (best 
developed in fully adult individuals; fig. 4B) 
and lack dorsally visible postorbital constric- 
tions; palatine fenestrae are present, and the 
auditory bullae are small and conical. The 
upper canine lacks accessory cusps, and M4 
is very wide. 
The remaining Bolivian material that we 
refer to Marmosops noctivagus is from the 
foothills and lower montane regions of Beni, 
Cochabamba, and La Paz. The specimens in 
question include the type material of doro- 
thea and yungasensis, but an older name for 
the same phenotype is keaysi (from southern 
Peru; appendix 1).!' Measurements of rep- 
resentative examples (including relevant type 
material; table 10) indicate that these high- 
land specimens are about the same size as 
typical dowland) noctivagus, but they have 
(on average) slightly broader interorbital re- 
gions, shorter molar rows, and narrower 
fourth upper molars. In addition, the dorsal 
fur tends to be slightly longer, the palatal fe- 
nestrae to be somewhat larger, and the bullae 
to be more inflated in highland examples 
than in lowland specimens. Also, whereas 
'T Although Anderson (1997: 152-154) reported 
““Marmosops dorothea’” and ‘“‘Marmosops noctivagus 
keaysi”’ as co-occuring at Chijchijpa in the department 
of La Paz, all of the specimens in question (at AMNH 
and MSB) are taxonomically indistinguishable. Ander- 
son’s records of these taxa from Chijchijpa therefore rep- 
resent alternative identifications (apparently copied from 
skin labels), not sympatry. 
