2004 
Natural History (New York); BMNH, Natu- 
ral History Museum (London); CBE Colec- 
cidn Boliviana de Fauna (La Paz); FMNH, 
Field Museum of Natural History (Chicago); 
INPA, Instituto Nacional de Pesquisas da 
Amazonia (Manaus); MNCN, Museo Na- 
cional de Ciencias Naturales (Madrid); 
MNRJ, Museu Nacional (Rio de Janeiro); 
MSB, Museum of Southwestern Biology 
(University of New Mexico, Albuquerque); 
MVZ, Museum of Vertebrate Zoology (Uni- 
versity of California, Berkeley); ROM, Royal 
Ontario Museum (Toronto); UMMZ, Univer- 
sity of Michigan Museum of Zoology (Ann 
Arbor); USNM, National Museum of Natural 
History (Washington, D.C.); ZMB, Museum 
fiir Naturkunde der Humboldt-Universitat zu 
Berlin (Berlin); and ZMUC, Zoological Mu- 
seum of the University of Copenhagen (Co- 
penhagen). In addition, we examined a small 
number of uncataloged specimens (cited by 
field number: LHE, Louise H. Emmons; 
MJS, Matthew J. Swarner) that will eventu- 
ally be transferred to the USNM. 
We transcribed total length (nose to fleshy 
tail-tip, TL) and length of tail (basal flexure 
to fleshy tip, LT) from specimen labels or 
field notes, and we computed head-and-body 
length (HBL) by subtracting LT from TL. We 
also transcribed length of hind foot (heel to 
tip of longest claw, HF), length of ear (from 
notch, Ear), and weight from specimen labels 
or field notes, but we sometimes remeasured 
HF on fluid-preserved specimens to check 
the accuracy of values recorded by the col- 
lector, and we used our values whenever 
large discrepancies were found. All external 
measurements are reported to the nearest mil- 
limeter, and all weights are reported to the 
nearest gram. 
Craniodental measurements were taken 
with digital calipers and recorded to the near- 
est 0.01 mm, but values reported herein are 
rounded to the nearest 0.1 mm. The following 
were measured as illustrated in figure 2: 
Condylo-Basal Length (CBL): Measured from the 
occipital condyles to the anteriormost point of 
the premaxillae. 
Nasal Breadth (NB): Measured across the triple- 
point sutures of the nasal, frontal, and maxillary 
bones on each side. 
Least Interorbital Breadth (LIB): Measured at the 
narrowest point across the frontals between the 
VOSS ET AL.: BOLIVIAN MARMOSOPS a 
orbits, even when the postorbital constriction 
(between the temporal fossae) is narrower. 
Zygomatic Breadth (ZB): Measured at the widest 
point across both zygomatic arches. 
Palatal Length (PL): Measured from the anterior- 
most point of the premaxillae to the postpala- 
tine torus, including the postpalatine spine (if 
present). 
Palatal Breadth (PB): Measured across the labial 
margins of the fourth molar (M4) crowns, at or 
near the stylar A position. 
Maxillary Toothrow Length (MTR): Measured 
from the anterior margin of the canine (C1) to 
the posterior margin of the fourth molar (M4). 
Length of Molars (LM): Measured from the an- 
teriormost labial margin of M1 to the posteri- 
ormost point on M4. 
Length of M1—M3 (M1—M3): Measured from the 
anteriormost labial margin of M1 to the poste- 
riormost point on M3. 
Width of M4 (WM4): Measured from the labial 
margin of the crown at or near the stylar A 
position to the lingual apex of the protocone. 
Except as noted below, all analyzed char- 
acter data were obtained from adult speci- 
mens as determined by dental criteria. Fol- 
lowing Voss et al. (2001), a specimen was 
judged to be juvenile if dP3 is still in place; 
subadult if dP3 has been shed but P3 and/or 
M4 are still incompletely errupted; and adult 
if the permanent dentition is complete. Qual- 
itative character variation is described herein 
using terminology that is explained or ref- 
erenced by Voss and Jansa (2003) and Wible 
(2003). An exception (not defined by those 
authors) is the prefix “‘self-’? as used in com- 
bination with descriptors of ventral pelage 
color, such as self-white or self-cream. This 
usage applies to hairs that have the same col- 
oration from base to tip, as opposed to hairs 
that are basally gray and distally white or 
cream (for example). 
TAXONOMIC ACCOUNTS 
Marmosops Matschie, 1916 
TYPE SPECIES: Marmosops incanus (Lund, 
1840) by original designation. 
DIAGNOsIs: Species of Marmosops can be 
distinguished from other small didelphid 
marsupials by the following combination of 
character states: eye surrounded by mask of 
blackish fur contrasting in color with paler 
fur of crown and cheeks; dorsal pelage uni- 
