24 AMERICAN MUSEUM NOVITATES 
The holotype of Marmosops creightoni 
was collected by EY near the Saynani hy- 
droelectric generating station at 2500 m on 
the southeastern side of the valley. The ob- 
viously disturbed forest at this site consisted 
of patches with a closed canopy but also 
open areas with isolated trees. The trees were 
laden with epiphytes, and the ground cover 
consisted of vines, small bamboo, grasses, 
moss, and ferns. The holotype was taken on 
the ground, in a snap trap set in dense grass 
under a small tree. All of the other small 
mammals trapped at Saynani by EY and oth- 
er researchers are sigmodontine rodents, in- 
cluding Akodon mimus, Chibchanomys sp., 
Microryzomys minutus, Oryzomys levipes, 
Oxymycterus nigrifrons, and the same unde- 
scribed forms of Oligoryzomys and Thoma- 
somys that occur at Cuticucho. 
In summary, Marmosops creightoni has 
been collected in both primary cloud forest 
and disturbed vegetation in the Valle de Zon- 
go, where it occurs sympatrically with Gra- 
cilinanus aceramarcae and several species of 
sigmodontine rodents between 2000 and 
3000 m above sea level. A different species 
of Marmosops, however, inhabits lower ele- 
vations in the Zongo valley. Two specimens, 
one from El Vertigo at 1800 m (CBF 4003) 
and another from Kahua at 1150 m (CBF 
3880), are both referable to M. noctivagus as 
we recognize that species below. Future col- 
lecting in the elevational interval between 
2000 and 1000 m would be helpful in pin- 
pointing just where these congeneric species 
occur sympatrically or parapatrically along 
the forested eastern slopes of the Cordillera 
Real. 
NOTES ON THE TAXONOMY AND 
DISTRIBUTION OF OTHER 
BOLIVIAN FORMS 
In the course of searching museum collec- 
tions for additional examples of Marmosops 
creightoni, we examined many other Boli- 
vian specimens of Marmosops and sorted 
them into phenotypically distinctive groups 
that we provisionally recognize as species. 
The following accounts summarize our con- 
clusions about the taxonomy and distribution 
of these forms based on currently available 
information. For each species recognized be- 
NO. 3466 
TABLE 7 
Measurements (mm) and Weights (g) 
of the Brazilian Holotype and Referred 
Bolivian Material of Marmosops bishopi 



Brazil Bolivia 
USNM AMNH CBF MSB LHE 
3935354 268938 7531 55843 1541b 
Sex female female male male male 
HBL 102 90 105 93 96 
LT 116 120 130 137 126 
HF 15 15 15 17 15 
Ear 21 21 22 21 19 
CBL 26.6 26.2 27.3 26.9 26.7 
NB 3.3 3.5 3.4 3.3 3.5 
LIB 5.4 5.2 5.5 5.4 5.1 
ZB 14.5 13.4 14.1 13.7 14.2 
PL 14.7 14.8 15.2 14.9 15.0 
PB 8.8 8.4 8.2 8.3 8.0 
MTR 11.0 11.2 10.8 10.9 10.6 
LM 5.6 5.8 5.6 5.7 5.4 
M1—M3 4.8 5.0 5.0 5.1 4.8 
WM4 2.1 2.0 1.8 2.0 1.8 
Weight — 17 22 18 18 

aThe holotype, from Mato Grosso, Brazil. 
‘To be cataloged in the USNM collections. 
low, we explain the morphological and other 
criteria that were used to assign names, and 
we note conflicting identifications of the 
same material reported by Anderson (1997), 
the most authoritative available reference on 
Bolivian mammalogy.? 
Marmosops bishopi 
This appears to be the appropriate name 
for Bolivian specimens of the Marmosops 
parvidens group, of which we have exam- 
ined eight examples from widely scattered 
localities in Beni, Cochabamba, La Paz, and 
Santa Cruz (fig. 10). These are all very small 
animals (table 7) with much shorter molar 
series (LM < 5.8 mm) than any other Boli- 
vian congener. The skulls have rounded su- 
praorbital margins that lack distinct beading, 
shallow postorbital constrictions are dorsally 
visible, there are no palatine fenestrae, and 
° Because Anderson (1997) seldom cited museum cat- 
alog numbers, we consulted his card file of examined 
specimens (preserved in the AMNH Department of 
Mammalogy archives) to determine the empirical basis 
for mapped collection localities of Bolivian Marmosops 
(Anderson, 1997: figs. 493-495). 
