Giant anteater from northwestern Venezuela
9
ANARTIA
Publicación del Museo de Biología de la Universidad del Zulia
ISSN 1315-642X (impresa) / ISSN 2665-0347 (digital)
Anartia, 34 (junio 2022): 9-17
Cranial anatomy of the giant anteater from northwestern
Venezuela (Myrmecophaga tridactyla artata,
Pilosa: Myrmecophagidae)
Anatomía craneana del oso hormiguero gigante del noroccidente de Venezuela
(Myrmecophaga tridactyla artata, Pilosa: Myrmecophagidae)
Juan D. Carrillo1,2 *, Luis E. Sibira3 & Tito R. Barros3
1Department of Biology, University of Fribourg, and Swiss Institute of Bioinformatics, 1700, Fribourg, Switzerland
2Gothenburg Global Biodiversity Centre, SE-405 30, Gothenburg, Sweden
3Museo de Biología, Facultad Experimental de Ciencias, Universidad del Zulia, Maracaibo, Venezuela.
Correspondence: juan.carrillo@uni.ch
(Recibido: 23-12-2021 / Aceptado: 06-07-2022 / En línea: 30-09-2022)
ABSTRACT
e giant anteater (Myrmecophaga tridactyla) has a wide geographical distribution in Central and South America. ree
subspecies are tentatively recognized for populations in Central America and west of the northern Andes (M. tridactyla
centralis Lyon, 1906), northern Colombia and northwestern Venezuela (M. tridactyla artata Osgood, 1912), and the rest
of South America (M. tridactyla tridactyla Linnaeus, 1758). Myrmecophaga tridactyla artata is the less known of the three
subspecies, and few specimens are deposited in zoological collections. Recent collecting eorts of specimens from north-
western Venezuela allow us to better characterize this morphotype and evaluate morphological dierences with the other
two subspecies. We found that adult specimens of M. t. artata show smaller cranial dimensions in comparison with M. t.
centralis and M. t. tridacytyla. We document a higher morphological variation than previously recognized in the cranial
sutures that have been hypothesized to dierentiate the subspecies. Although M. t. artata shows smaller cranial dimen-
sions than M. t. centralis and M. t. tridactyla, additional data integrating information from the genetic variation and other
morphological regions is required to further evaluate the morphological and genetic dierences of the three recognized
subspecies. e recently collected specimens of M. t. artata studied herein shed light on the cranial morphological varia-
tion and overlap among the three recognized subspecies of the giant anteater.
Keywords: Xenarthra, crania, South America, tropics, morphology.
RESUMEN
El oso hormiguero gigante (Myrmecophaga tridactyla) tiene una amplia distribución geográca en Centro y Suramérica.
Tres subespecies son reconocidas para las poblaciones de Centroamérica y el oeste del norte de los Andes (M. tridactyla
centralis Lyon, 1906), el norte de Colombia y el noroeste de Venezuela (M. tridactyla artata Osgood, 1912), y el resto de
Sudamérica (M. tridactyla tridactyla Linnaeus, 1758). Myrmecophaga t. artata es la menos conocida de las tres subespecies,
y hay pocos ejemplares depositados en colecciones zoológicas. Recientes esfuerzos de colección de ejemplares atropellados
en el noroeste de Venezuela nos permiten caracterizar mejor este morfotipo y evaluar las diferencias morfológicas con las
otras dos subespecies. Los individuos adultos de M. t. artata tienen unas dimensiones craneanas menores en comparación
con M. t. centralis y M. t. tridacytyla. Adicionalmente, documentamos una variación morfológica mayor que la reconocida
anteriormente en las suturas craneales que se han propuesto para diferenciar las subespecies. Aunque M. t. artata muestra
unas dimensiones craneanas más pequeñas que M. t. centralis y M. t. tridactyla, se necesitan datos adicionales que integren
J. D. Carrillo, L. E. Sibira & T. R. Barros
10
la información de la variación genética y de otras regiones morfológicas para evaluar más a fondo las diferencias morfológi-
cas y genéticas de las tres subespecies reconocidas. Los ejemplares de M. t. artata recientemente recolectados y estudiados
aportan nueva información sobre la variación de la anatomía craneana entre las tres subespecies reconocidas del oso hor-
miguero gigante.
Palabras clave: Xenarthra, cráneo, Suramérica, trópico, morfología.
between the nasals and the frontals, and the squamosal
and sphenoid. e description of M. t. centralis was based
on a juvenile specimen from Costa Rica, but some of its
characteristics are observed also in adults from Honduras
(Mérida Colindres & Cruz Dias 2014). M. t. artata was
INTRODUCTION
e giant anteater (Myrmecophaga tridactyla Linnaeus,
1758) is the largest extant representative of the order Pi-
losa (Gaudin et al. 2018). M. tridactyla is terrestrial and
inhabits a wide range of habitats, from wet rainforests to
dry savannahs (Rodrigues et al. 2008). e skull of giant
anteaters is characterized by several adaptations to myr-
mecophagy (ant- and termite eating; Redford 1987) such
as long and edentulous snouts, protractile tongues, and
reduced masticatory apparatus (Naples 1999, Casali et al.
2017, Ferreira-Cardoso et al. 2020b). It is hypothesized
that the giant anteater originated from the extinct taxon
Neotamandua (Rovereto 1914, Hirschfeld 1976), at about
8.1 million years ago (Ma) (Casali et al. 2020). Among the
living taxa, the giant anteater is closely related to the genus
Tamandua Gray 1825 (Tamandua mexicana and Taman-
dua tetradactyla) with an estimate time of divergence at
about 13 Ma (12.7 Ma estimated by Gibb et al. [2016] and
13.6 Ma estimated by Casali et al. [2020]).
Several studies focused on the phenotypic variation
among widely distributed myrmecophagous mammals
(Ferreira-Cardoso et al. 2020a), including tamanduas
(Reeve 1940, Wetzel 1975) and the silky anteaters (genus
Cyplopes Gray 1821) (Miranda et al. 2018). Reeve (1940)
proposed the existence of several subspecies within Ta-
mandua tetradactyla and Tamandua mexicana based of
internal and external morphological traits, while Miranda
et al. (2018) showed that Cyclopes is constituted of at least
seven cryptic species.
Similar to other pilosans (Hayssen 2011, Navarrete &
Ortega 2011, Miranda et al. 2018), the giant anteater is
widely geographically distributed, spanning from Central
America to Southern Brazil (Fig. 1). Gardner (2007) and
Gaudin et al. (2018) tentatively recognized three subspe-
cies for populations in central America, and west of the
Andes in Colombia and Ecuador (Myrmecophaga tridac-
tyla centralis Lyon 1906), northern Colombia and north-
western Venezuela (Myrmecophaga tridactyla artata Os-
good 1912) (Pittier & Tate 1932, Linares 1998), and rest
of South America (Myrmecophaga tridactyla tridactyla)
(Fig. 1). M. t. centralis was described originally as a new
species by Lyon (1906) based on dierences of the sutures
Figure 1. Geographic distribution of Myrmecophaga tridac-
tyla showing the distribution of the three subspecies (Gardner
2007, Gaudin et al. 2018). M. t. centralis (green), M. t. artata
(orange), and M. t. tridactyla (light blue). e range distribu-
tion of M. t. artata and M. t. tridactyla in Venezuela was modi-
ed from Gaudin et al. (2018) and Linares (1998). e type
locality of M. t. artata (Empalado savannas; Osgood 1912)
is indicated by the black star. e new specimens of M. t. ar-
tata studied in this work come from nearby the type locality
(Supplementary Table 1). Geographic range map distribution
of M. tridacyla was modied from Miranda et al. (2014). e
light purples represents the extension of the distribution range
in Colombia following Chacón Pacheco et al. (2017).
Giant anteater from northwestern Venezuela
11
described by Osgood (1912) based mainly on a narrower
rostrum (narrower nasals and less expanded maxillaries)
than the two other subspecies. Given its restricted dis-
tribution, the populations from northern Colombia and
north-western Venezuela (tentatively designated as the
subspecies M. t. artata; Linares 1998, Gaudin et al. 2018)
are poorly known. During a period of ve years (2008-
2013), one of the authors (TRB) has collected several
individuals in northwestern Venezuela (Falcón and Zulia
states), all of which were road-killed in a section of paved
road of 81 km, from the bifurcation towards Los Puertos
de Altagracia (10.581033, -71.473431) until Santa Cruz
(10.877166, -70.881389). In this work we study the cra-
nio-mandibular anatomy of the giant anteater from north-
western Venezuela (M. t. artata) with the aim to better
characterize this morphotype and evaluate morphological
dierences with the other two tentative subspecies (M. t.
centralis and M. t. tridacytla).
MATERIALS AND METHODS
We measured 65 dry skulls of museum specimens of
Myrmecophaga tridactyla collected across dierent locali-
ties in Central and South America (Carrillo et al. 2022;
Supplementary Table 1). e specimens represent the
three tentatively recognized subspecies, M. t. centralis
(2specimens), M. t. artata (10 specimens) and M. t. tri-
dactyla (37 specimens), and zoo animals (6 specimens).
Nine specimens had no locality information (Supplemen-
tary Table 1). In addition, we included one specimen of
M. t. centralis with the measurements reported by (Mérida
Colindres & Cruz Dias 2014). For the statistical analyses
to compare the three tentatively recognised subspecies, we
excluded the zoo specimens and specimens without local-
ity information.
We took the following 14 linear measurements (Fig.2):
(1) Skull length (SL), from the most dorso-caudal point
Table 1. Principal Component eigenvalues, variables correlations and contribution to the rst ve dimensions. Dim =
dimension; var. = variance; cor = correlation; contr = contribution. e numbers and abbreviations of the variables corres-
pond to the ones described in the text.
Variance Dim 1 Dim 2 Dim 3 Dim 4 Dim 5 Dim 6 Dim 7 Dim 8 Dim 9 Dim 10
7.1 1.64 1.14 0.82 0.82 0.64 0.52 0.47 0.28 0.25
% of var. 50.71 11.68 8.12 5.87 5.86 4.59 3.72 3.39 2.02 1.77
Cumulative
% of var. 50.71 62.39 70.51 76.38 82.24 86.83 90.55 93.94 95.96 97.74
Variables Dim 1 Dim 2 Dim 3 Dim.4 Dim 5
cor contr Cor contr cor contr cor contr cor contr
1. SL 0.93 12.26 0.04 0.08 -0.06 0.32 0.11 1.48 -0.09 0.97
2. CL 0.96 13.05 -0.02 0.01 0.05 0.22 0.04 0.19 -0.1 1.14
3. WS 0.79 8.81 -0.22 3 -0.28 6.94 0.02 0.07 -0.15 2.83
4. AW 0.33 1.51 -0.83 42.57 0.13 1.54 0.13 1.98 -0.22 5.67
5. LW 0.69 6.73 0.1 0.65 -0.39 13.44 0.33 13.14 0.12 1.89
6. ML 0.93 12.18 0.07 0.31 0.09 0.66 -0.04 0.24 -0.13 1.98
7. OW 0.76 8.14 -0.31 5.97 0.16 2.2 -0.18 4.04 -0.08 0.78
8. OCW 0.7 6.89 -0.22 2.88 0.02 0.03 -0.09 0.89 0.36 15.82
9. FMH 0.25 0.9 0.57 19.8 0.45 17.82 0.45 24.58 -0.08 0.74
10.CH 0.62 5.43 0.22 2.92 0.43 16.03 0.11 1.51 0.06 0.37
11. PL 0.56 4.37 -0.04 0.08 0.16 2.12 -0.16 3.13 0.7 59.27
12. PW 0.47 3.07 0.37 8.47 -0.66 37.91 0.03 0.08 0.03 0.13
13. VL 0.96 13.09 0.02 0.02 0.05 0.18 0.02 0.07 -0.09 0.96
14. LD 0.5 3.54 0.47 13.24 0.08 0.59 -0.63 48.62 -0.25 7.45
J. D. Carrillo, L. E. Sibira & T. R. Barros
12
of the occipital to the most rostral point of the nasal;
(2) Condylobasal length (CL), from the most caudal
point of the occipital condyle to the most rostral point of
the maxilla. (3) Width between the squamosal processes
(WS), distance between the most rostro-lateral point of
the squamosal processes of the temporal; (4) Anterior
width (AW), the distance between the most rostral point
of the maxillas; (5) Lacrimal width (LW), the distance
between the most lateral point of the lacrimals; (6) Max-
illa length (ML), from the most caudal to the most ros-
tral point of the maxilla; (7) Occipital width (OW), the
distance between the most caudal point of the occipital-
parietal sutures; (8) Occipital condyles width (OCW),
the distance between the most lateral points of the oc-
cipital condyles; (9) Foramen magnum height (FMH),
dorso-ventral height of the foramen magnum; (10) Cra-
nial height (CH), from the most ventral point of the fora-
men magnum to the most dorsal point of the occipital;
(11) Palatal length (PL), from the most caudal point of the
palatine to the most rostral point of the maxilla; (12)Pal-
atal width (PW), the distance between the most caudo-
lateral point of the palatines; (13) Ventral length (VL),
from the most caudal point of the sphenoid to the most
rostral point of the maxilla; (14) Length of dentary (LD),
from the most caudal point of the mandibular condyle to
the most rostral point of the mandibular symphysis. All
specimens measured are adults (as indicated by the closed
supraoccipital-exoccipital suture), except for one subadult
individual representing M. t. tridactyla (NRM 586631),
for which this suture is not completed closed (Fig. 2e). We
used a calliper to the nearest 0.1 mm and a metric tape for
large measurements (>15 cm).
Data were collected from specimens from the follow-
ing institutions: ZMUZH, Zoologisches Museum der
Universität Zürich; MBLUZ, Museo de Biología de la
Universidad de Zulia, Maracaibo; MNHN, Muséum
national d’Histoire naturelle, Paris; ZMB, Museum für
Naturkunde, Berlin; ZSM Zoologisches Staatssammlung,
München; ICN, Instituto de Ciencias Naturales, Bogotá;
NRM, Naturhistorika riskmuseet, Stockholm; GNM,
Göteborgs Naturhistorika Museum Gothenburg; and
COSEM-MAS, Instituto Commemorativo Gorgas de
Ciencias de la Salud, Panama.
e following analyses were performed on the sample
of specimens that could be assigned to one of the three
subspecies (n=50). We tted a linear regression of the
skull length and lacrimal width (chosen as a measurement
to represent relative skull width). In addition, to compare
the relative width and length of the skull among the three
subspecies, we estimated the ratio of lacrimal width / skull
Figure 2. Linear measurements used in this study. Measurements are illustrated in a skull of M. t. artata (MBLUZ-0249) in dorsal view
(a), ventral view (b), and caudal view (c). e numbers correspond to the list of measurements described in materials and methods.
d.Caudal view of the only subadult specimen (NRM 586631) in the sample (as indicated by supraoccipital- exoccipital suture not
fully closed), referred to M. t. tridactyla.
Giant anteater from northwestern Venezuela
13
length. We also performed a principal component analysis
(PCA) (Dryden & Mardia 1993) on the 14 skull measure-
ments in order to visualize the skull shape variation. We
used the missMDA package (Josse & Husson 2016) to
impute some missing values, because not all the 14 mea-
surements could be taken in all the specimens studied.
e missing value imputation uses the regularized iterative
PCA algorithm which considers the similarities of ob-
servations and the relationships of the variables. In brief,
the algorithm substitute missing values with initial values
(e.g., mean of the variable with no missing entries), then
performs a PCA and use the tted matrix to dened new
imputed data (the observed values remain the same, but
the missing values are replaced by the tter values). is
process is repeated until the change of the imputed matrix
is below a pre-dened threshold (Josse & Husson 2016).
We did the PCA using the FactoMineR package (Husson
et al. 2020). All analyses and plots were made in R (R Core
Team 2021).
RESULTS
e bivariate plot of skull length and lacrimal width
shows a positive relationship between the two variables
(adjusted R2 = 0.48, p-value < 0.001). Overall, the speci-
mens representing M. t. artata tend to have shorter and
narrower skulls in comparison with specimens represent-
ing M. t. tridactyla, whereas the three specimens of M. t.
centralis show intermediate values of skull length (Fig.3a).
When comparing the relative width and length of the
Figure 3. Skull dimensions and morphospace occupation of the three recognized subspecies of Myrmecophaga tridactyla: M. t. centralis
(green), M. t. artata (red), M. t. tridactyla (blue). e text indicates the position of a subadult specimen of M. t. tridactyla (NRM
586631). a. Bivariate plot of the skull length and lacrimal width. e black line and grey shade show the tted linear regression and
the standard error of estimate, respectively. b. Boxplot of the width/length ratio (lacrimal width/skull length). c. Principal Component
Analysis (PCA) showing the distribution of individual specimens. d. Bivariate plot of the rst dimension of the PCA and skull length.
e black line and grey shade show the tted linear regression and the standard error of estimate, respectively.
J. D. Carrillo, L. E. Sibira & T. R. Barros
14
skull (width/length ratio), M. t. artata shows a smaller ra-
tio in comparison with M. t. centralis and M. t. tridactyla
(Fig.3b).
e rst dimension of the PCA explains 50.7%, where-
as the second one explains 11.7% (Fig. 3c; Table 1). e
rst dimension correlates with skull length (adjusted R2 =
0.87, p-value < 0.001; Fig 3d). e subadult specimen of
M. t. tridactyla (NRM 586631) has a skull length that is
within the range of values for the adult specimens of M.
t. artata (Fig. 3a). Similarly, NRM 586631 has the lowest
value for the rst dimension of the PCA in our sample,
and it is closer to the value of several adult specimens of M.
t. artata than adult specimens of M. t. tridactyla (Fig. 3d).
DISCUSSION
e statistical analyses of the cranial measurements
suggest that the specimens from north-western Venezu-
ela (M. t. artata) are overall smaller than the specimens
from Central America (M. t. centralis) and specimens
from elsewhere in South America (M. t. tridactyla). e
specimens of M. t. artata show shorter and narrower (as
measured by the lacrimal width) skulls, and smaller values
on the rst dimension of the PCA (which correlates with
skull length) in comparison with the two other subspecies
(Fig.3). Interestingly, the only subadult specimen in our
sample referred to M. t. tridactyla (NRM 586631, which
comes from the Beni Department in Bolivia) has a skull
length within the range of adult specimen of M. t. artata,
and it has a value on the rst PCA dimension that is closer
to some adult specimens of M. t. artata than to adult speci-
mens of M. t. tridactyla.
Some potential qualitative osteological dierences
have been proposed among the three recognized subspe-
cies. In the description based on a juvenile, Lyon (1906)
noted that in M. t. centralis the latero-rostral extension of
the frontal bones is at the same level that the most rostral
extension of the inter-frontal suture, whereas in M. t. tri-
dactyla the latero-rostral extension of the frontals is much
closer to the most caudal extension of the nasals. Osgood
(1912) regarded the fronto-nasal suture condition in M.
t. artata as somehow intermediate between M. t. centralis
and M. t. tridactyla. However, an examination of the adult
specimens from the three subspecies available to us indi-
cates that M. t. centralis shows a similar condition to M. t.
artata. In adult specimens of M. t. centralis, the latero-ros-
tral extension of the frontals (red dots in Fig. 4a) is close to
the midpoint between the most rostral point of the inter-
frontal suture (black dots in Fig. 4a), and the most caudal
point of the nasals (blue dots in Fig. 4a).
e fronto-nasal suture morphology in specimens of
M. t. artata from northwestern Venezuela is similar to
the condition seen in the M. t. centralis specimens from
Panama; but specimens of M. t. tridactyla show a position
of the latero-rostral extension of the frontals (red dots in
Fig. 4a) much closer to the most caudal extension of the
nasals (blue dots in Fig. 4a), even in the subadult specimen
from Bolivia.
Lyon (1906) also noted that in M. t. centralis, the most
rostral extension of the squamosal is located closer to the
root of the zygomatic than to the most rostral extension
of the sphenoid. is condition has also been observed in
adult specimens of M. t. centralis from Honduras (Mérida
Colindres & Cruz Dias 2014). According to Lyon (1906),
in M. t. tridactyla the rostral extension of the squamosal is
located about the midpoint between the root of the zygo-
matic and the rostral extension of the sphenoid. We notice
variation in the squamosal-sphenoid suture morphology
among the specimens examined, without clear dierences
among the three subspecies (Fig. 4b). In the adult speci-
mens of M. t. centralis, the most rostral extension of the
squamosal (red diamonds in Fig. 4b) is not as closed to
the root of the zygomatic (blue diamonds in Fig. 4b), as
in the juvenile specimen described by Lyon (1906). Fur-
thermore, the subadult specimen of M. t. tridactyla (NRM
586631; Fig. 4b) shows a condition more similar to the one
described for the juvenile of M. t. centralis (Lyon 1906),
suggesting that dierences in the relative position of the
most rostral extension of the squamosal (red diamonds in
Fig. 4b) with respect to the root of the zygomatic (blue
diamonds in Fig. 4b) and the most rostral extension of the
sphenoid (black diamonds in Fig. 4b) might reect onto-
genetic growth.
Morphological dierences in the cranial sutures of
populations of M. tridactyla have been used to dene three
subspecies ( Lyon 1906, Osgood 1912, Gardner 2007,
Gaudin et al. 2018). e collection of new specimens from
northwestern Venezuela (M. t. artata) allows us to better
characterize this morphotype and evaluate morphological
dierences with the other two subspecies. We document
a higher morphological variation than previously recog-
nized in the cranial sutures that have been hypothesized
to dierentiate the subspecies. M. t. artata shows smaller
cranial dimensions than M. t. centralis and M. t. tridactyla,
and additional analyses integrating data from the genetic
variation and from other morphological regions (e.g., in-
ternal morphological structures such as the paranasal si-
nuses; e.g., Billet et al. 2017) are required to further evalu-
ate the morphological and genetic dierences of the three
recognized subspecies.
Giant anteater from northwestern Venezuela
15
Figure 4. Morphological variation of the cranial sutures in three recognized subspecies of the giant anteater (Myrmecophaga tridactyla).
a. Dorsal view of the skulls showing the relative position the most rostral point of the interfrontal suture (black dot), the most caudal
point the nasals (blue dot), and the most latero-rostral extension of the frontals (red dot) in specimens representing the three subspe-
cies of M. tridactyla. b. Ventral view of the skulls showing the relative position of the most rostral point of the squamosal (red diamond)
in relationship with the root of the zygomatic (blue diamond) and the most rostral extension of the alisphenoid (black diamond) in
specimens representing the three subspecies of M. tridactyla. M. t. centralis (le, COSEM-MAS 1033; right COSEM-MAS 1034)
from Panama; M. t. artata from northwestern Venezuela (le, MBLUZ-0245; right, MBLUZ-M251), and M. t. tridactyla (le, ZSM
1931/312, from Paraguay, and right NRM 586631, subadult from Bolivia).
J. D. Carrillo, L. E. Sibira & T. R. Barros
16
CONCLUSION
e giant anteater (Myrmecophaga tridactyla) has a
wide geographic distribution in Central and South Amer-
ica, and three subspecies are tentatively recognized (Gard-
ner 2007, Gaudin et al. 2018). Of the three subspecies, M.
t. artata is poorly known and few specimens are available
for study in zoological collections (Linares 1998). New
specimens from north-western Venezuela allowed us to
document the cranial anatomy of M. t. artata and evaluate
potential morphological dierences with the other two
recognized subspecies. M. t. artata shows overall smaller
cranial dimensions for adult specimens in comparison
with specimens of M. t. centralis and M. t. tridactyla, but
it is dicult to dierentiate the subspecies based on the
morphology of the cranial sutures, as previously hypoth-
esized. e specimens of M. t. artata studied herein shed
light on the cranial morphological variation and overlap
among the three recognized subspecies of the giant ant-
eater.
ACKNOWLEDGEMENTS
We would like to thank the following curators and
museums for access to the collections under their care:
D. Kaltho (Naturhistoriska riksmuseet, Stockholm),
M. Gelang (Naturhistoriska Museum, Gothenburg), G.
Veron (Museum National d’Histoire Naturelle, Paris),
S. Bock (Museum für Naturkunde, Berlin), A. H. van
Heteren (Zoologische Staatssammlung, Munich), M.
Schenckel (Zoological Museum, University of Zurich), H.
López and C. Cárdenas (Instituto de Ciencias Naturales,
Bogotá), A. Cornejo and C. A. Nieto (Instituto Com-
memorativo Gorgas de Estudios de la Salud, Panama), and
G. A. Rivas (Museo de Biología, La Universidad del Zu-
lia). A special thanks to A. Abreu, A. Baran, R. Barboza,
M. A. Campos, M. Ortega, D. Revilla, J. Yores and G. A.
Rivas for their support in the eld work and laboratory.
J.D.C. was supported by the Swiss National Science Foun-
dation grants P2ZHP3_174749 and P400PB_186733,
and the Helge Ax son Johnson Stielse grant F18-0486.
Collecting permits in Venezuela were granted by the
Ministerio del Poder Popular para el Ambiente under
numbers 5416 (22/10/2008), 665 (10/02/2010) and
1027(24/10/2013). We acknowledge two anonymous
reviewers. We thank M. R. Sánchez-Villagra for logistical
support of our work in Venezuela, D. Cortés for assistance
in the measurements and photographs of specimens of
M. t. centralis in Panama, and G. Billet, L. Hautier, and S.
Ferreira-Cardoso for valuable comments.
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