Bon AMERICAN MUSEUM NOVITATES 
NO. 3466 
TABLE 12 
Geographic and Elevational Distribution of Small Nonvolant Cloud-Forest Mammals 
Collected Sympatrically with Marmosops creightoni 

N Known distribution Reference 
Gracilinanus aceramarcae 5 N Bolivia to central Peru; 2530-3350 m R. S. Voss (unpublished data) 
Akodon mimus 14 Central Bolivia to SE Peru; 2000-3635 m Myers et al. (1990) 
Microryzomys minutus 131 Central Bolivia to Venezuela; 800-4265 mb> Carleton and Musser (1989) 
Oxymycterus nigrifrons 10 N Bolivia to SE Peru; 2000-4200 m Oliveira (1998) 
Thomasomys “sp. 1” 7 N Bolivia to central Peru; 1880-3650 m Pacheco (2003) 
Thomasomys “sp. 3” 11 N Bolivia to SE Peru; 2000-3275 m Pacheco (2003) 

aNumber of collection localities accompanied by elevational data. 
bMost (>80%) collection localities for Microryzomys minutus are between 2000 and 3500 m (Carleton and Musser, 1989). 
veloped palatine fenestrae, much larger teeth 
(LM = 6.7 mm), and by lacking accessory 
cusps on Cl. 
The other unidentified specimen is MSB 
63275, a young adult female from the Rio 
Limon at 1300 m on the lower Andean 
slopes of northeastern Chuquisaca. It has 
browner and somewhat paler dorsal fur than 
does the Rio Ariruma material, and self- 
cream ventral fur with broad lateral bands of 
gray-based hairs (versus underparts entirely 
self-white). However, the crania of all three 
specimens are not dissimilar, and they differ 
from those of recognized Bolivian taxa by 
essentially the same characters. 
DISCUSSION 
Bolivia encompasses a diversity of land- 
scapes with different vegetation types that 
might be expected to support distinct faunas. 
As currently recognized in the literature, 
however, Bolivian species of Marmosops 
have broadly overlapping distributions that 
do not coincide with any obvious biogeo- 
graphic regions or macrohabitats. Although 
we have not examined all of the material rep- 
resented in published range maps, the spec- 
imens identified in this report suggest that 
some species have much more geographical- 
ly restricted and ecologically comprehensible 
distributions than do those illustrated by An- 
derson (1997) and Brown (2004). 
Specimens that fit our working diagnosis 
of Marmosops noctivagus (a total of 53 in- 
dividuals from 17 localities) are from the 
lowland rain forests and lower-montane 
cloud forests of northern and central Bolivia, 
a region that approximately corresponds to 
the Amazonian (“‘Acre y Madre de Dios’’) 
and “‘Yungas”’’ biogeographic provinces of 
Navarro and Maldonado (2002). This species 
is also widespread in eastern Peru and west- 
ern Brazil, where it has been collected in 
similar habitats (Voss and Emmons, 1996; 
Patton et al., 2000). Future collecting in Bo- 
livia will probably show that M. noctivagus 
occurs throughout Pando department, in the 
forested parts of La Paz up to about 2000 m 
on the eastern Andean slopes, along the for- 
ested Andean foothills of southernmost Beni, 
and on the Andean piedmont and lower-mon- 
tane slopes of Cochabamba to at least 18°S. 
The other Bolivian species for which we 
have examined enough material to character- 
ize its ecogeographic distribution (a total of 
37 individuals from 20 localities) is Mar- 
mosops ocellatus, which seems to be wide- 
spread in the “‘Cerrado”’ biogeographic prov- 
ince of Navarro and Maldonado (2002). 
Within this region, however, M. ocellatus has 
only been trapped in closed-canopy forests, 
not in the savanna woodlands or shrubby 
habitats that characterize Cerrado sensu stric- 
to (L.H. Emmons, in litt.). We expect that 
future collecting will show that M. ocellatus 
occurs throughout those parts of Santa Cruz 
receiving about 1000-1500 mm of annual 
rainfall and in similar habitats of southwest- 
erm Brazil (Mato Grosso). 
Although currently known from only three 
adjacent localities in La Paz, Marmosops 
creightoni is almost certainly more wide- 
spread. Based on the known geographic 
ranges of other small nonvolant cloud-forest 
mammals that occur in the same elevational 
interval in the Valle de Zongo (table 12), we 
