Taxonomy, distribution, and natural history of the genus Heteromys (Rodentia, Heteromyidae) in western Venezuela : with the description of a dwarf species from the Península de Paraguaná

43 Pages·2003·5.1 MB·English

by  Anderson, Robert P

AMERICAN MUSEUM
Novitates
PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY
CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024
Number 3396, 43 pp., 12 figures, 4 tables March 27, 2003
Taxonomy, Distribution, and Natural History of
the Genus Heteromys (Rodentia: Heteromyidae) in
Western Venezuela, with the Description of a
Dwart Species from the Peninsula de Paraguana
ROBERT P. ANDERSON!”
CONTENTS
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RETEreHCES* (tee roe ack orn lgts ee ade, OE re tee aS, SN, 29
' Roosevelt Postdoctoral Research Fellow, Division of Vertebrate Zoology (Mammalogy), American Museum of
Natural History. e-mail: [email protected]
? Natural History Museum and Department of Ecology & Evolutionary Biology, University of Kansas, Lawrence,
KS 66045.
Copyright © American Museum of Natural History 2003 ISSN 0003-0082
2 AMERICAN MUSEUM NOVITATES NO. 3396
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2003 ANDERSON: HETEROMYS IN WESTERN VENEZUELA
ABSTRACT
Heteromys anomalus is widely distributed along the Caribbean coast of South America and
was generally considered the only spiny pocket mouse present in Venezuela until H. australis
was reported recently from the Cordillera de Mérida. Here, I revise the spiny pocket mice of
western Venezuela and compare specimens from the semi-insular Peninsula de Paraguana with
samples from throughout the distributional area of H. anomalus. Morphological comparisons
with all other species of the genus suggest that the Heteromys from Paraguana are closely
related to H. anomalus, but univariate and multivariate analyses show that they are much
smaller than samples of H. anomalus. In addition, adults from Paraguana display differences
in cranial shape when compared with adults of H. anomalus. Hence, specimens from Para-
guana are here described as a new species, Heteromys oasicus, and taxonomic treatments of
H. anomalus and H. australis in western Venezuela are also provided. Although the original
geographic context of this case of dwarfism in body size is unknown, H. oasicus currently
appears to be isolated in mesic vegetation on the low Cerro Santa Ana and Fila de Monte
Cano, which lie in a matrix of tropical thorn forest. The new species represents one of the
few vertebrates considered endemic to Paraguané, but basic inventories and taxonomic studies
are not yet complete in the region.
RESUMEN
Heteromys anomalus esta ampliamente distribuido a lo largo de la costa caribefia de Sur-
américa y habia sido considerada la Unica especie de rat6n de abazones (= rat6én mochilero;
raton bolsero; rat6n bols6n) presente en Venezuela, hasta que H. australis fue reportado re-
cientemente para la Cordillera de Mérida. En el presente estudio se revisa la taxonomia de los
Heteromys del occidente de Venezuela y se comparan ejemplares de la Peninsula de Paraguana
con muestras representativas de toda la distribuci6n geografica de H. anomalus. Las compar-
aciones morfoldgicas con las restantes especies del género indican que los ratones mochileros
de Paraguana estan estrechamente relacionados con H. anomalus, pero los andlisis univariados
y multivariados demuestran que aquéllos poseen un tamafio corporal mucho menor que las
series analizadas de H. anomalus. Ademas, las proporciones craneanas en los adultos de Para-
guana muestran diferencias con respecto a los adultos de H. anomalus. Por lo tanto, se des-
criben a los ejemplares de Paraguana como representantes de una especie nueva, Heteromys
oasicus. Ademas, se presentan resimenes taxonomicos para H. anomalus y H. australis en el
occidente de Venezuela. Aunque no se conoce definitivamente el contexto geografico original
de este caso de enanismo de tamafio corporal, actualmente H. oasicus parece confinada a
vegetacion relativamente himeda en el Cerro Santa Ana y la Fila de Monte Cano, que se
encuentran rodeados por una matriz de espinares y matorrales secos tropicales. La nueva
especie representa a una de los pocos vertebrados que se consideran endémicos de Paraguana;
no obstante, el inventario basico de la regidén atin no ha sido realizado de manera exhaustiva
y resulta indispensable el desarrollo de estudios taxonémicos detallados para la mayoria de
los taxones.
INTRODUCTION and Heteromys is the only genus of the fam-
ily to have colonized South America, where
Spiny pocket mice (Heteromys and Lio-
it is restricted to the northwestern portion of
mys) belong to the family Heteromyidae, the continent.
which originated in North America (Wood,
Spiny pocket mice are terrestrial grani-
1935; Hershkovitz, 1969, 1972; Rogers, vores found primarily in forested habitats
1990; Webb, 1997). These two genera form (Sanchez-Cordero and Fleming, 1993). Spe-
the subfamily Heteromyinae, a monophyletic cies of Liomys inhabit deciduous forests and
group within the family (Hafner, 1981; Haf- other semiarid tropical habitats from south-
ner and Hafner, 1983; Wahlert, 1985). The ern Texas to Panama (Genoways, 1973; Wil-
center of extant heteromyid diversity lies in liams et al., 1993). In contrast, species of
the southwestern United States and Mexico, Heteromys inhabit wetter (usually evergreen)
- AMERICAN MUSEUM NOVITATES NO. 3396
forests from southern Mexico to northwest- Atrato/Rio San Juan lowlands (= Bolivar
ern South America. Although a few morpho- Geosyncline; Hershkovitz, 1972).
logical characters exist to diagnose the gen- Before Heteromys australis was reported
era (Williams et al., 1993), their reciprocal for Venezuela (Anderson and Soriano, 1999),
monophyly has not yet been demonstrated in most recent publications listed H. anomalus
any phylogenetic analysis (see Rogers [1990] as the only pocket mouse present in the
for poorly resolved phenetic clustering of country (e.g., Eisenberg, 1989; Soriano and
species based on variation at allozyme loci). Ochoa-G., 1997; Linares, 1998). Previously,
Six (Williams et al., 1993) or seven (Patton, however, Handley (1976) had noted the pres-
1993) species of Heteromys have been rec- ence of an undescribed species of Heteromys
ognized in recent faunal lists, but current tax- from the Peninsula de Paraguana in north-
onomy underestimates the true diversity of western Venezuela (see fig. 1). This arid pen-
the genus (Rogers, 1990; Patton, 1993; An- insula is connected to the rest of the main-
land only by a “long, narrow sparsely veg-
derson, 1999). Recently, Anderson and Ja-
rrin-V . (2002) described an additional species etated isthmus”’ (Handley, 1976: 78; see also
from Ecuador. Barnes and Phelps, 1940; Romero, 1989;
Two species of Heteromys are known to Markezich and Taphorn, 1994; Markezich et
al., 1997). The Heteromys from Paraguana
be widespread in South America, and two
were found solely from the base and upper
have restricted distributions. Heteromys
slopes of a low, isolated mountain (Cerro
anomalus inhabits both deciduous and ever-
Santa Ana), which lies in a xeric lowland
green tropical forests in northern South
matrix of thorn forest characteristic of most
America, typically up to ca. 1500-1600 m.
of the peninsula. In contrast, the upper slopes
It is distributed along the Caribbean coast of
of Cerro Santa Ana hold cloud forest and
Colombia and Venezuela (including Isla
other mesic vegetation above approximately
Margarita) and in Trinidad and Tobago
550 m, a low proportion of its surface (Bis-
(Musso-Q., 1962; Handley, 1976; Anderson,
bal-E., 1990). Further specimens were re-
1999; Anderson and Soriano, 1999), but not
ported from Cerro Santa Ana as H. anomalus
in Panama (Anderson, 1999; contra Rogers,
by Bisbal-E. (1990), who captured them only
1990; Méndez, 1993; Williams et al., 1993;
on the upper slopes of the cerro. Addition-
Nowak, 1999). The species is also known
ally, two heretofore unreported specimens
from parts of the dry Magdalena Valley in
exist from the Fila de Monte Cano (see ap-
Colombia (Hernandez-Camacho, 1956; An-
pendix 1), a nearby low ridge that is predom-
derson, 1999). In contrast, H. australis is re-
inately covered by thorn forests but that also
stricted to very mesic evergreen forests in the
includes relatively mesic vegetation along a
Choco of northwestern Ecuador, western Co-
seasonal watercourse (Romero, 1989; M.
lombia, and eastern Panama, as well as
Diaz, in litt.).
throughout much of the Colombian Andes up
In the present study, I evaluate the taxo-
to ca. 2500 m in elevation (Anderson, 1999).
nomic status of populations of Heteromys
A disjunct population also exists in the Uri-
from the Peninsula de Paraguana. To do so,
bante drainage of the Cordillera de Mérida
I complete the revision of H. anomalus in
in western Venezuela (Anderson and Sori- Colombia (begun in Anderson, 1999), extend
ano, 1999; Anderson et al., 2002). In addi- it to western Venezuela, and make quantita-
tion to these widespread taxa, a new species tive comparisons with large series and type
(H. teleus) was recently described from cen- material available from Colombia, Venezue-
tral-western Ecuador, where it inhabits ever- la, and Trinidad. Future work will revise the
green but highly seasonal forests (Anderson genus in eastern Venezuela.
and Jarrin-V., 2002). Finally, a species of the
Heteromys desmarestianus complex (provi- MATERIALS AND METHODS
sionally referred to as H. d. crassirostris) is
MUSEUM SPECIMENS
present in high montane regions of the Se-
rrania del Darién in extreme northwestern Eight hundred twenty-four specimens
Colombia (Anderson, 1999), west of the Rio from the following museum collections form
2003 ANDERSON: HETEROMYS IN WESTERN VENEZUELA 5
the basis of this report (abbreviations follow specimens were assigned to the age classes
Hafner et al., 1997; Lew and Ochoa, 1993; of Rogers and Schmidly (1982). Age classes
and Bisbal-E. and Sanchez-H., 1997; an as- 1—3 represent juveniles and subadults,
terisk denotes collections with material from whereas classes 4—6 are progressively older
western Venezuela, as defined below): adults. Age classes do not constitute a con-
tinuous variable (such as absolute age), but
AMNH American Museum of Natural His-
rather are categories roughly corresponding
tory, New York*
to relative age within population samples
ANSP Academy of Natural Sciences, Phil-
adelphia (see Voss et al., 1990).
CM Carnegie Museum of Natural His- Material reported here from the principal
tory, Pittsburgh* study area (appendix 1) includes the over-
CVULA Colecci6n de Vertebrados de la whelming majority of specimens of Heter-
Universidad de los Andes, Mérida* omys from western Venezuela available in
EBRG Museo de la Estacion Bioldgica de
museums in the United States and Venezuela
Rancho Grande, Maracay, Aragua*
(and all that I have examined). Note, how-
FMNH Field Museum [formerly Field Mu-
ever, a few important records from the Ven-
seum of Natural History], Chicago*
ICN Instituto de Ciencias Naturales, ezuelan /lanos (tropical savannas) reported
Universidad Nacional de Colombia, by Utrera et al. (2000), which I have not ex-
Bogota amined. Western Venezuela is here consid-
IND-M Instituto de Investigacién de Recur- ered as the area west of the Depresi6n de
sos Biol6gicos Alexander von Hum-
Yaracuy (SAGCN, 1995; ~ Depresi6n de
boldt (= IAvH; includes former IN-
Lara sensu Soriano et al., 1999). This low-
DERENA collection), Villa de Lei-
land region separates the Cordillera de Mé-
va, Boyaca
rida from the Cordillera de la Costa (fig. 1)
KU University of Kansas Natural His-
and, for the purposes of this paper, is delim-
tory Museum, Lawrence*
LACM Natural History Museum of Los An- ited by the rivers Yaracuy, Cojedes, and Apu-
geles County, Los Angeles re (not shown). In addition, I report all spec-
MBUCV Museo de Biologia de la Universi- imens of H. anomalus known to me from
dad Central de Venezuela, Caracas* Colombia, including some not noted in An-
MCNUSB- Museo de Ciencias Naturales de la
derson (1999). For statistical analyses, I take
Universidad Simon Bolivar, Baruta/
advantage of the several largest series of that
Caracas*
species available from localities throughout
MCZ Museum of Comparative Zoology,
Harvard University, Cambridge its range (see Geographic Variation). Finally,
MHNLS Museo de Historia Natural La Salle, I compare these Heteromys qualitatively with
Caracas* representative samples of all other currently
MLS Museo del Instituto La Salle, Bogota accepted species of the genus, including the
MVZ Museum of Vertebrate Zoology, majority of extant holotypes (appendix 2).
University of California, Berkeley Where original elevation was reported in
UF Florida Museum of Natural History,
feet, I provide that datum as well as the met-
University of Florida, Gainesville*
ric equivalent to the nearest whole number.
UMMZ University of Michigan Museum of
Zoology, Ann Arbor
USNM United States National Museum of MEASUREMENTS
Natural History, Washington, DC*
GY: Universidad del Valle, Cali Standard cranial measurements for Heter-
UWZM University of Wisconsin Zoological omys (fig. 2) follow Anderson and Jarrin-V.
Museum, Madison*
(2002). I took these measurements to the
I examined specimens for discrete char- nearest 0.01 mm with digital calipers (except
acters and patterns of variation in the exter- for specimens from the ICN collection,
nal and cranial anatomy. Cranial nomencla- which were measured to the nearest 0.1 mm
ture follows Wahlert (1985), Anderson with dial calipers) on intact skulls from se-
(1999), and Anderson and Jarrin-V. (2002). lected localities as described below and listed
Based on patterns of toothwear and molt, in appendix 3. External measurements and
6 AMERICAN MUSEUM NOVITATES NO. 3396
y SD 68°
Caribbean Sea b
4{ Paraguana
Isla de Margarita
aw Naiguata Manacal Caura ap
Caracol—ic-it o {t}p i l m: m, S Y&a cambu ooa it# tpagSe .e \ 1—9, @" Pat .m Neveri NE‘ __ FBBouursseshht
COLOMBIA ,#
Depresion de Yaracuy
VENEZUELA 0 100 200
Cucuchica ————|
kilometers
Fig. 1. Map of north-central South America showing the approximate position of primary geographic
samples of Heteromys anomalus (@) and of Heteromys from the Peninsula de Paraguana (A) used here.
Gray shading approximates regions more than 1000 m in elevation. See appendices 1 and 2 for complete
provenience and museum catalog numbers and appendix 3 for a list of measured specimens.
mass were copied from specimen tags and, rietal crests at right angle to longitudinal axis
when necessary, from primary field notes. of cranium.
Skull depth (SD): greatest distance from dorsal-
Occipitonasal length (ONL): greatest distance most point of braincase to horizontal plane
from anteriormost projection of nasal bones to passing through ventral borders of maxillary
posteriormost portion of occipital bone. cheek teeth and ventral borders of occipital
Zygomatic breadth (ZB): greatest width across zy- condyles (taken by placing skull on glass mi-
gomatic arches at right angle to longitudinal croscope slide with upper incisors rested over
axis of cranium. edge of slide, and then subtracting thickness of
Rostral length (RL): greatest distance from notch slide).
lateral to lacrimal bone to anteriormost projec-
tion of nasal bone on same side of cranium.
STATISTICAL ANALYSES
Nasal length (NL): greatest distance from ante-
riormost projection of one nasal bone to its pos- GENERAL PROTOCOLS: Except where oth-
teriormost projection (not necessarily at medial
erwise noted, statistical analyses were per-
suture between nasals).
formed with Minitab (1996; version 11.12).
Least interorbital constriction (IOC): least width
Probability levels reported here should be re-
across interorbital constriction at right angle to
garded as approximate, given moderate sam-
longitudinal axis of cranium.
ple sizes in most groups that preclude tests
Squamosal breadth (SB): width across squamosal
anterior to external auditory meatus at right an- of multivariate normality. These approximate
gle to longitudinal axis of cranium. probabilities were compared to a significance
Maxillary toothrow length (MTR): distance from level of a = 0.05 for all tests, except where
anterior lip of alveolus of premolar to posterior modified to adjust for multiple tests (see be-
lip of alveolus of third molar. low). Descriptive statistics were calculated
Interparietal width (IW): greatest transverse width for specimens from the Peninsula de Para-
measured from lateralmost projections of inter- guana and for the 12 primary geographic
parietal bone at right angle to longitudinal axis
samples of H. anomalus (see Geographic
of cranium.
Variation) in age class 4, which was the most
Interparietal length (IL): greatest distance from
abundant adult age class.
anteriormost projection of interparietal bone to
Principal components analyses (PCA)
posteriormost border of interparietal bone, al-
ways taken along medial line of cranium even were conducted on the covariance matrix of
log-transformed measurements following
when notch present in posterior border.
Parietal breadth (PB): greatest width across pa- Jolicoeur (1963); natural logarithms (log, or
2003 ANDERSON: HETEROMYS IN WESTERN VENEZUELA y
Fig. 2. Dorsal, ventral, and lateral views of a cranium of Heteromys, showing method of taking
cranial measurements. Abbreviations and measurements are defined in the Materials and Methods.
In) were used here. PCA is a multivariate or- ing similar interpretations. I only interpreted
dination technique that extracts axes of max- principal components with clearly distinct e1-
imum dispersion among specimens without genvalues (by inspection). For visual presen-
regard to the group (e.g., geographic sample) tation of specimen scores on multivariate
to which specimens belong. Each resultant axes, I scale the axes of a given analysis rel-
axis (principal component) is characterized ative to their eigenvalues (proportion of var-
by an eigenvector with coefficients that in- iation explained) in plots of specimen scores
dicate the relationship of each variable to that on those axes.
multivariate axis. I also present principal Discriminant function (DFA) and canoni-
components as loadings, which are Pearson cal variates (CVA) analyses were performed
product-moment correlation coefficients be- in SAS 6.12 for UNIX (SAS, 1990; PROC
tween specimen scores on each axis and the DISCRIM and PROC CANDISC) on log,-
log,-transformed variables. Both unit eigen- transformed cranial measurements. A DFA
vectors and loadings are commonly used to tests for differences among centroids (mul-
identify and explain multivariate axes, yield- tivariate means) of groups (e.g., geographic
8 AMERICAN MUSEUM NOVITATES NO. 3396
samples) specified by the investigator. Sig- which particular pairs of geographic samples
nificance for comparisons between particular were significantly different from each other.
pairs of geographic samples in the DFAs was The statistical power for each pair varied ac-
determined using F-statistics of Mahalanobis cording to the sample sizes involved.
distances between pairs of group centroids Additionally, to test for differences in mul-
and Holm’s (1979) modification of the Bon- tivariate means among geographic samples
ferroni procedure correcting for multiple and to examine the basis of any differences
comparisons. Here, statistical power varies present, a DFA and CVA were conducted on
for each pair according to the sample sizes the same dataset with geographic sample de-
involved. Complementary to DFA, CVA is noting group membership. An ANOVA with
an ordination technique that extracts multi- Tukey’s comparisons was performed for
variate axes that maximize variation among scores on Cl,,,, as for PC1,., from the PCA.
group centroids. For interpretation, I present I also conducted a second DFA/CVA with
these canonical axes solely as loadings. I ex- the putative species forming the only two
plain and further discuss only canonical axes groups: the Paraguana specimens versus all
with clearly distinct eigenvalues. other samples pooled together.
GEOGRAPHIC VARIATION: I quantitatively COMPARISONS AMONG TYPE SAMPLES: A
compared adult specimens of Heteromys second PCA was conducted comparing the
from the Peninsula de Paraguana with 12 sample from Paraguana with material repre-
geographic samples of Heteromys anomalus senting Heteromys anomalus and the other
from Colombia, Venezuela, and Trinidad (all nominal taxa considered synonyms of it.
in age class 4; fig. 1). The sample from Para- Adults of age classes 4—6 were analyzed to-
guana included specimens from both Cerro gether here to take maximal advantage of
Santa Ana and Monte Cano (Paraguand, Es- small sample sizes. A one-way ANOVA and
tado Falcé6n). The samples of H. anomalus Tukey’s comparisons by nominal taxon were
included one in northern Colombia (Cara- conducted on specimen scores on the result-
colicito, Departamento del Cesar), nine ing PC1,,,.. When possible, I used measure-
across northern Venezuela (Tukuko, Estado ments from holotypes and associated type se-
Zulia; Cucuchica, Estado Mérida; Valera, ries that I have examined: H. anomalus
Estado Trujillo; Yacambu, Estado Lara; Ra- hershkovitzi Hernandez-Camacho, 1956; H.
fael Rangel, Estado Aragua; Naiguatd, Es- Jesupi Allen, 1899; and H. anomalus brachi-
tado Vargas; Neveri, Estado Sucre; Latal, Es- alis Osgood, 1912. To represent the nomi-
tado Sucre; and Manacal, Estado Sucre), and notypical form described from ‘*Trinidad”’
two in Trinidad and Tobago (Caura, Trini- (Thompson, 1815), I used early collected
dad, and Bush Bush Forest, Trinidad). These specimens from Caura (on the island of Trin-
geographic samples were chosen for their idad) as well as measurements for the holo-
relatively large sample sizes and geographic type of H. anomalus reported by Williams et
dispersion. In some cases, nearby localities al. (1993). Thus, this PCA was conducted
were pooled to create the samples (appendi- only using RL, NL, IOC, and MTR (the four
ces 1 and 3). measurements available for the holotype of
To examine the multivariate structure of H. anomalus). I did not have access to the
the data and determine how much of the var- holotypes of H. melanoleucus Gray, 1868 or
iation among specimens of the same age Perognathus bicolor (Gray, 1868), both of
class corresponds to geographic variation, which Williams et al. (1993) considered full
specimens in age class 4 from these samples synonyms of H. a. anomalus. Apparently, no
were submitted to a principal components holotype exists for H. thompsonii, a name
analysis with males and females pooled. A that Lesson (1827) clearly used to refer to
one-way analysis of variance (ANOVA) was the spiny pocket mouse from Trinidad named
performed by geographic sample on PC1,,., by Thompson (1815).
scores, testing for differences in means In addition to the holotype of Heteromys
among samples on that axis. Tukey’s com- jJesupi, Allen (1899) mentioned 12 other ex-
parisons between all pairs of sample means amined specimens from various localities in
on PCl,., were also conducted to determine the same region (all in the vicinity of Santa
geo
2003 ANDERSON: HETEROMYS IN WESTERN VENEZUELA g
Marta, Colombia) in his description of that
taxon. In total, 13 specimens of Heteromys
(AMNH 15344-15356) were cataloged in
sequence along with the type, but they do not
correspond exactly to the localities listed by
Allen. I suggest that his first mention of Bon-
da (Allen, 1899: 201) should read Onaca,
and that he included two specimens from El
Libano Plantation in the count for the nearby
locality Masinga Vieja. Thus, I use these 13
specimens to represent the type series of H.
Jesupi.
SYSTEMATICS
The analyses indicate the presence of three
species of Heteromys in western Venezuela,
for which I provide the following taxonomic
treatments. Except for the one record of H.
australis known from the country (Anderson
and Soriano, 1999), all specimens examined
from western Venezuela outside the Penin-
sula de Paraguana match the characterization
of H. anomalus presented in Anderson
(1999). Clear differences separate the Para-
Fig. 3. Dorsal, ventral, and lateral views of
guana Heteromys from all other species of
the holotype of Heteromys oasicus (USNM
the genus except H. anomalus, which is quite
456325), a male in age class 4.
similar to it in discrete morphological char-
acters. However, the species of spiny pocket
mouse present on the Peninsula de Paraguana
restricted distribution along watercourses and
differs from H. anomalus by strikingly small-
other relatively mesic areas on Cerro Santa
er body size, cranial proportions of adults,
Ana and Monte Cano. There, suitable habitat
and pelage characters. To refer to it, I pro-
for the species exists due to mist coming off
pose the name:
the ocean, surrounded by a matrix of xero-
phytic habitat on the remainder of the Penin-
Heteromys oasicus, new species
sula de Paraguana.
Paraguana Spiny Pocket Mouse
DISTRIBUTION: Known only from Cerro
Figures 3, 7
Santa Ana (fig. 4) and the Fila de Monte
HOLOTYPE: USNM 456325; adult male; Cano on the Peninsula de Paraguana, Estado
skin and skull in excellent condition (fig. 3). Falcon, Venezuela. Likely restricted to small
Collected on 25 July 1968 by Norman E. Pe- areas of evergreen and semideciduous vege-
terson from Venezuela: Estado Falcén: 49 tation on the peninsula (figs. 5, 6).
km N, 32 km W of Coro, Cerro Santa Ana, DIAGNOsIS: A species of spiny pocket
at 550 m. Original number SVP (Smithson- mouse with adults showing the following
ian Venezuelan Project) 24036. combination of characters: p4 (lower per-
PARATYPES: The following specimens manent premolar) with 3 lophs; P4 (perma-
(adults skins and skulls in good condition) nent upper premolar) with straight, moder-
from the type locality are designated as para- ately deep fold in anterior border of posterior
types: EBRG 15110, 15111; USNM 456327. loph; mesopterygoid fossa V-shaped, with
ETYMOLOGY: Latinized from the Greek long, thin hamular processes of pterygoids;
oasis (a fertile spot in a desert) using the Lat- optic foramen small, with exterior margin
in suffix -icus, belonging to or pertaining to formed by strong bar of bone; parietomastoid
(Brown, 1956), in reference to the species’ suture dipping well ventral to parietal crest
10 AMERICAN MUSEUM NOVITATES NO. 3396
Fig. 4. Landscape at Cerro Santa Ana (localities 101 and 102; Estado Falcén), showing vertical
stratification of vegetation types on its slopes. Upper: View of Cerro Santa Ana from the WNW. Note