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Rediscovery of Atractus microrhynchus and Reappraisal of the Taxonomic Status of A. emersoni and A. natans (Serpentes: Dipsadidae)


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Resumen La especie Rhabdosoma microrhynchum (ahora Atractus microrhynchus) se basó en un solo espécimen colectado por la Expedición Orton en “Guayaquil,” provincia de Guayas, costa Pacífica del Ecuador. El holotipo está actualmente perdido y todos los especímenes previamente referidos a esta especie fueron identificados erróneamente sobre la base de material de la Amazonía Peruana. Durante la revisión de colecciones de museos y la realización de trabajo de campo en las tierras bajas del Pacífico de Ecuador y Perú, encontramos especímenes que se pueden asignar a A. microrhynchus. En este estudio, reportamos sobre la variación morfológica de estos nuevos especímenes de A. microrhynchus y evaluamos el estado taxonómico de las especies Amazónicas previamente confundidas con esta. Restringimos el concepto de A. microrhynchus para las poblaciones de las tierras bajas del Pacífico de Ecuador y Perú y designamos un neotipo para la especie. Basados en la revisión de los tipos de A. emersoni y A. natans de la Amazonía, encontramos que hay una amplia superposición de las características de ambos taxones. Por lo tanto, A. emersoni se coloca bajo la sinonímia de A. natans. Más aún, comparamos A. microrhynchus con todos sus congeners y sus afinidades con el grupo-de-especies A. multicinctus son discutidos sobre la base de las características hemipenianas exclusivas compartidas.
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Herpetologica, 68(3), 2012, 375–392
Ó 2012 by The Herpetologists’ League, Inc.
Departamento de Vertebrados, Museu Nacional, Universidade Federal do Rio de Janeiro, Quinta da Boa Vista,
Rio de Janeiro, RJ, 20940-040, Brazil
Universidad San Francisco de Quito, College of Biological and Environmental Sciences, Avenida Interocea
Campus Cumbaya, Edif
ıcio Darwin, of. DW010A, Casilla Postal 17-12-841, Quito, Ecuador
Departamento de Herpetologia, Museo de Historia Natural, Universidad Mayor de San Marcos, Avenida Arenales 1256,
us Maria, Apartado 14-0434, Lima, Peru
Department of Biology, The University of Texas at Arlington, Arlington, TX 76019, USA
BSTRACT: The species Rhabdosoma microrhynchum (now Atractus microrhynchus) was originally
described based on a single specimen collected by the Orton Expedition at ‘‘Guayaquil,’’ in the Guayas
province on the Pacific coast of Ecuador. The holotype is currently lost and all specimens previously referred
to this species were misidentified on the basis of material from Peruvian Amazonia. While examining museum
collections and conducting fieldwork in the Pacific lowlands of Ecuador and Peru, we found specimens
assignable to A. microrhynchus. In this study, we report the morphological variation in these new specimens
of A. microrhynchus and evaluate the taxonomic status of the Amazonian species previously confused with it.
We restrict the concept of A. microrhynchus to the Pacific lowland populations from Ecuador and Peru, and
we designate a neotype for the species. Based on the examination of the types of A. emersoni and A. natans
from Amazonia, we found that there is wide overlap in the internal and external characters of both taxa.
Therefore, A. emersoni is relegated to the synonymy of A. natans. Furthermore, we compared A.
microrhynchus with all congeners and discuss its affinities with the A. multicinctus species group based on
shared, exclusive hemipenial features.
ESUMEN: La especie Rhabdosoma microrhynchum (ahora Atractus microrhynchus) se bas
o en un solo
ecimen colectado por la Expedici
on Orton en ‘‘Guayaquil,’’ provincia de Guayas, costa Pac
ıfica del
Ecuador. El holotipo esta
actualmente perdido y todos los espec
ımenes previamente referidos a esta especie
fueron identificados err
oneamente sobre la base de material de la Amazon
ıa Peruana. Durante la revisi
on de
colecciones de museos y la realizaci
on de trabajo de campo en las tierras bajas del Pac
ıfico de Ecuador y
u, encontramos espec
ımenes que se pueden asignar a A. microrhynchus. En este estudio, reportamos
sobre la variaci
on morfol
ogica de estos nuevos espec
ımenes de A. microrhynchus y evaluamos el estado
omico de las especies Amaz
onicas previamente confundidas con esta. Restringimos el concepto de A.
microrhynchus para las poblaciones de las tierras bajas del Pac
ıfico de Ecuador y Per
u y designamos un
neotipo para la especie. Basados en la revisi
on de los tipos de A. emersoni y A. natans de la Amazon
encontramos que hay una amplia superposici
on de las caracter
ısticas de ambos taxones. Por lo tanto, A.
emersoni se coloca bajo la sinon
ımia de A. natans.Ma
un, comparamos A. microrhynchus con todos sus
congeners y sus afinidades con el grupo-de-especies A. multicinctus son discutidos sobre la base de las
ısticas hemipenianas exclusivas compartidas.
Key words: Amazonia; Atractus multicinctus species group; Hemipenial features; Morphological
variation; Pacific lowlands; Species boundaries
THE DIPSADINE snake genus Atractus Wa-
gler 1828, comprises small- to moderate-sized
snakes that have secretive lifestyles and feed
on earthworms, arthropods, and molluscs
(Passos et al., 2010c). The genus is widely
distributed in the Neotropics from Panama to
Argentina (Giraudo and Scrocchi, 2000;
Myers, 2003); it occurs primarily on the
mainland from sea level to 4500-m elevation
and occupies almost all South American
biomes (Passos et al., 2010c). Atractus is a
highly diverse genus that is closely related to
Adelphicos Jan, 1862 and Geophis Wagler,
1830 (Savage, 1960; Downs, 1967; Fernandes,
1995; Zaher, 1999; Passos, 2008), comprising
approximately 130 valid species, most of them
known to date only from their proper type
specimens (Passos and Fernandes, 2008;
Prudente and Passos, 2008; Passos et al.,
2009b,c,d,e). Although many currently recog-
nized species remain poorly evaluated, much
of our understanding of the taxonomy of
Atractus has been considerably improved in
the past 5 yr (Cisneros-Heredia, 2005; Passos
et al., 2005; Zaher et al., 2005; Kok, 2006;
Myers and Schargel, 2006; Prudente and
Santos-Costa, 2006; Kok et al., 2007; Passos
et al., 2007a,b; Passos and Fernandes, 2008;
Prudente and Passos, 2008; Passos and
Arredondo, 2009; Passos et al., 2009a,b,c,d,e,
2010a,c; Prudente and Passos, 2010). Even so,
additional efforts must be made to address
problems of morphological variation, geo-
graphic ranges, sexual dimorphism, polymor-
phism, and ontogenetic change of coloration
remain problematic (Passos et al., 2010a). In
this sense, only by addressing all of these
aspects and, at the same time, rigorously
comparing newly obtained samples with the
large number of available names in the
literature can we clarify the species boundar-
ies of this complex and poorly understood
genus (Passos and Lynch, 2010).
Rhabdosoma microrhynchum (Cope, 1868)
was described based on a single individual
collected by the Orton Expedition at Guaya-
quil in the Pacific lowlands of Ecuador. Cope
(1868), in the original description, suggested
that this species was closely related to Atractus
badius (Boie, 1827). Subsequently, Cope
(1870) reported R. microrhynchum from
Pebas in the Peruvian Amazonia on the basis
of new material from the same expedition.
Boulenger (1894) redefined the genus Atrac-
tus and proposed the synonymization of R.
microrhynchum with A. badius. Savage
(1960), although resurrecting A. microrhyn-
chus, considered that the taxonomic status of
this species could not be accurately assessed
because the original description was brief and
the holotype was apparently lost. Savage
(1960) also suggested the possibility that the
type locality could be wrongly labeled given
that the Orton Expedition collected material
on both sides of the Andes and that no
additional specimens referable to A. micro-
rhynchus had been collected in Guayaquil.
Dixon and Soini (1977) proposed once again
the synonymy of A. microrhynchus with A.
badius based on specimens from the Iquitos
region in Peru. Hoogmoed (1980) designated
the lectotype of A. badius and did not
consider A. microrhynchus as a proper
synonym of the latter species, restricting the
distribution of A. badius to the Guayana
region. In light of the new definition of A.
badius, Dixon and Soini (1986) reconsidered
the taxonomic status of their Iquitos speci-
mens as Atractus cf. microrhynchus. In spite
of Hoogmoed’s work, some authors still
consider A. badius to be a widespread taxon
distributed in Amazonian and Andean regions
of Colombia and Peru (P
erez-Santos and
Moreno, 1988; Carrillo and Icochea, 1995)
or even the junior synonyms (A. subbicinctus
[Jan, 1862] and A. micheli Mocquard, 1904) to
be valid species (Claessen, 2002, 2003).
Hoogmoed and Prudente (2003) described
A. natans on the basis of three individuals
from extreme (west and east) portions of
Brazilian Amazonia (Uarini approximately
1000 km east of Melga¸co), but restricted their
comparisons to species distributed in Central
Amazonia and the Guiana Shield. Subse-
quently, Silva (2004) described A. emersoni
based on two specimens from Benjamin
Constant in Brazil, and another individual
from Leticia in Colombia, near the border
between Brazil and Peru. Despite the geo-
graphic proximity of the type locality of A.
emersoni to Iquitos (approximately 360 km by
air), the author did not compare their putative
new taxon with Atractus cf. microrhynchus
(sensu Dixon and Soini, 1986). Recently,
Passos et al. (2009e) revised the taxonomic
status of Pacific lowland species of Atractus
and recognized 10 species distributed from
Colombia to Ecuador. In that paper, the
authors recognized A. microrhynchus as valid
species and mentioned newly discovered
material of the species apparently collected
near the type locality in Ecuador. Although
Passos et al. (2009e) pointed out that the
specimens examined by Dixon and Soini
(1977, 1986) actually refer to A. natans by
mistake, they cited both studies on the
synonymy list of A. microrhynchus. Therefore,
the inclusion of such references in the list of
synonymy of A. microrhynchus must be
interpreted as an error rather than an
ambiguity with respect to the status of the
specimens of the Iquitos Region.
376 [Vol. 68, No. 3
We redescribe A. microrhynchus based on
new specimens discovered in collections and
in the wild. We report on the meristic,
morphometric, hemipenial, and color-pattern
characters, and we propose a neotype for the
species. In addition, we evaluate the taxonom-
ic status of the Amazonian species that were
previously confused with A. microrhynchus,
and we discuss the affinities of A. micro-
rhynchus on the basis of morphological
We examined specimens in the following
institutions: Brazil—Museu Paraense Em
Goeldi (MPEG), Bel
em; Colombia—Instituto
de Ciencias Naturales (ICN), Universidad
Nacional de Colombia, Bogota
; Ecuador—
on de Herpetolog
ıa del Museo Ecuator-
iano de Ciencias Naturales (DHMECN),
Quito; Peru—Museo de Historia Natural de
la Universidad Mayor de San Marcos
(MUSM), Lima; and United States—Ameri-
can Museum of Natural History (AMNH),
New York; National Museum of Natural
History (USNM), Smithsonian Institution,
Washington DC; Texas Cooperative Wildlife
Collections (TCWC), Texas A&M University,
College Station. Geographic coordinates
(based on the datum WSG84) of localities
were recorded in the field, obtained from
museum databases, or taken from geograph-
ical gazetteers (Stephens and Traylor, 1983;
Paynter and Traylor, 1991). Whenever possi-
ble, we refined the coordinates obtained from
literature with aid of the software Google
Earth 6.2.
Characters used are based on meristics,
morphometrics, maxillary dentition, and hem-
ipenis morphology. Terminology for Atractus
cephalic shields follows Savage (1960), where-
as the method of counting ventral scales
follows Dowling (1951). Terminology used to
describe the condition of the loreal scale
follows Passos et al. (2007b). We took
measurements with dial calipers to the nearest
0.1 mm under an optical stereoscope, except
for snout–vent (SVL) and caudal lengths (CL);
SVL and CL were measured with a flexible
ruler to the nearest millimeter. The terminol-
ogy for body and tail size follows Passos et al.
(2009e). We took measurements for paired
cephalic shields only on the right side of the
head. Terminology for hemipenis descriptions
follows Dowling and Savage (1960) and Zaher
(1999). Techniques for hemipenis eversion of
preserved specimens follow Pesantes (1994).
Although all hemipenes have been completely
everted, some of them are not fully inflated, as
is common with preserved organs (Myers and
Cadle, 2003). We examined maxillae in situ
through a narrow lateromedial incision be-
tween supralabials and the maxillary arch. We
removed tissues covering the maxillary arch,
sockets. Terminology for teeth and maxillary
conditions follow Passos et al. (2009e). Addi-
tional specimens of Atractus examined are
listed in Passos et al. (2005; 2007a,b;
2009b,c,d,e; 2010a,b,c), Passos and Arredondo
(2009), Passos and Fernandes (2008), Passos
and Lynch (2010), Prudente and Passos (2008,
Atractus microrhynchus (Cope, 1868)
(Figs. 1–3)
Rhabdosoma microrhynchum Cope, 1868;
Proc. Acad. Nat. Sci. Philadelphia 1868:102.
Atractus badius Boulenger, 1894; Catalogue
of the Snakes in the British Museum vol.
2:308. (in part).
Atractus microrhynchus Savage, 1960;
Misc. Publ. Mus. Zool. Univ. Michigan 112:2.
Atractus microrhynchus Passos et al.,
2009e; Zootaxa 2293:19.
Holotype.—Unknown sex, California Acad-
emy of Sciences (CAS 6693), from Guayaquil
S, 79854
W, ca. 50 m above sea level
[asl]), Guayas Province, Ecuador, collected by
the Orton Expedition in 1867–1868. Savage
(1960) pointed out that the holotype was
missing at the CAS, and it currently remains
lost (N. Gilmore, personal observation).
Neotype.—Adult male, DHMECN 3008,
collected March 2005 by Francisco Sornoza
at Reserva Biol
ogica Buenaventura (03838
S, 79845
W, ca. 600 m asl), Parroquia
nas, Cant
on Pi
nas, El Oro Province, Ecua-
dor (by current designation; see Remarks).
Referred Specimens.—Juvenile male,
AMNH 108943, collected April 1972 by Rhea
Warren at R
ıo Palenque, 50 km N of Quevedo
September 2012] 377
S, 79827
W, ca. 110 m asl), Los R
Province, Ecuador. Adult males, MUSM
22829–30, collected 5–10 May 2005 by
Richard Cadenillas at Campo verde, Cerros
de Amotape National Park (between
S, 80809
W, 799 m asl and
S, 80811
W, 570 m asl), Tumbes
region, Peru.
Diagnosis.—Atractus microrhynchus is dis-
tinguished from all congeners by the following
combination of characters: (1) 17-17-17
smooth dorsal scale rows; (2) two postoculars;
(3) long loreal; (4) temporals 1þ2; (5) seven
supralabials, third and fourth contacting orbit;
(6) seven infralabials, first three contacting
chinshields; (7) six to seven maxillary teeth; (8)
three gular scale rows; (9) three preventrals;
(10) 143–150 ventrals in males; (11) 32–35
subcaudals in males; (12) dorsum brown to
light reddish brown, occasionally with paired
irregular white-bordered black blotches; (13)
ventral ground color cream, heavily marked
with dark-brown dots, forming an irregularly
blotched belly; (14) small body size in males
(reaching 293 mm SVL); (15) long tail in
males (18–18.1% of SVL); and (16) hemipenis
strongly bilobed, barely semicapitate, and
Comparisons.—Among all congeners, A.
microrhynchus shares a strongly bilobed
hemipenis with lobes of equivalent size or
longer than hemipenial body, sulcus sperma-
ticus bifurcating on the basal region of the
organ, and intrasulcar region with enlarged,
narrow hooked spines exclusively as with
members of the A. multicinctus (Jan, in Jan
and Sordelli, 1865) species group (sensu
Passos et al., 2009e). Atractus microrhynchus
differs from all of them by having a strongly
pigmented venter, with dark brown dots
irregularly distributed throughout (vs. venter
creamish white with dark spots, when present,
only on posterior region of body). On the basis
of external characters, A. microrhynchus
shares a reddish brown to reddish light brown
dorsal ground color only with A. dunni
Savage, 1955; A. echidna Passos, et al., 2009;
A. ecuadoriensis Savage, 1955; A. iridescens
Peracca, 1896; A. lasallei Amaral, 1931; A.
lehmanni Boettger, 1898; A. loveridgei Ama-
ral, 1930; and A. occidentalis Savage, 1955.
Atractus microrhynchus differs from A. dun-
ni, A. iridescens,andA. occidentalis in having
143–150 ventrals in males, a single postdias-
temal tooth, and a strongly bilobed and
slightly semicapitate hemipenis, with four
enlarged hooked spines arranged in longitu-
dinal series above the sulcus spermaticus
bifurcation (vs. 131–143 ventrals in A. occi-
dentalis; 128–144 in A. dunni, and 135–143 A.
iridescens; two postdiastemal teeth in the
three species; a moderately bilobed and non-
calyculate hemipenis with lateral projection
on the basal region of hemipenial body in A.
iridescens, hemipenis having a thick intra-
sulcar region with ca. 15 enlarged hooked
spines disposed on transversal [2/3/4/3/2]
FIG. 1.—Dorsal (A) and ventral (B) views of the
neotype of Atractus microrhynchus (DHMECN 3008),
from Reserva Biol
ogica Buenaventura, El Oro Province,
378 [Vol. 68, No. 3
series in A. dunni and A. occidentalis); from A.
echidna in having 17 dorsal scale rows (vs. 15);
from A. ecuadoriensis in having venter heavily
marked with brown dots and six or seven
maxillary teeth (vs. uniformly creamish white
venter and eight maxillary teeth); from A.
lasallei, A. lehmanni,andA. loveridgei in
having 32–35 subcaudals in males, five or six
prediastemal teeth with a single postdiastemal
tooth, and hemipenis strongly bilobed (vs. 20–
27 in A. lasallei, 23–29 in A. lehmanni, and
24–27 in A. loveridgei; seven to nine teeth
with two postdiastemal teeth; hemipenis
moderately bilobed). Other than differences
in color pattern (see above), A. microrhynchus
differs from A. natans in having 32–34
subcaudals in males, three infralabials con-
tacting chinshields, six or seven (5þ1 or rarely
6þ1) maxillary teeth, long tails in males, and
hemipenis strongly bilobed with distinct
moderately hooked spines on the intrasulcar
region of the capitulum (vs. 23–31 subcaudals
in males, four infralabials contacting chin-
shields, usually seven maxillary teeth [5þ2],
moderate tail size in males, and hemipenis
moderately bilobed lacking hooked spines on
intrasulcar region).
Description of Neotype.—Adult male, 275
mm SVL, 54 mm CL (19.6% of SVL); head
rounded in dorsal view, flattened in lateral
view, 10.2 mm long (3.7% of SVL), 6.6 mm
wide; head not distinct from body; snout
rounded in dorsal view, fairly truncated in
lateral view; rostrum–orbit distance 4.1 mm
(40.2% of head length); nostril–orbit distance
2.4 mm (23.5% of head length); intra-orbital
distance 4.2 mm (63.6% of head width); body
subcylindrical, body diameter 8.4 mm (3.1%
of SVL); belly flattened; tail moderately long,
with terminal spine rhomboid, slightly acumi-
FIG. 2.—Dorsal (left) and ventral (right) views of the Peruvian specimens of Atractus microrhynchus (A) MUSM
22829 and (B) MSUM 22830.
September 2012] 379
nate, and conical; rostral subtriangular, wider
(1.8 mm) than high (1.3 mm), visible from
above; internasal longer (1.0 mm) than wide
(0.8 mm wide); internasal suture sinistral
regarding prefrontal median suture; prefrontal
longer (2.5 mm) than wide (2.3 mm); frontal
triangular, approximately as wide (2.5 mm) as
long; supraocular irregularly trapezoidal, lon-
ger (1.4 mm) than wide (1.1 mm); parietal
approximately twice as long (4.4 mm) as wide
(2.6 mm); nasal divided; prenasal approxi-
mately twice as high (0.7 mm) as long,
contacting rostral, internasal, first supralabial,
and postnasal; postnasal approximately twice
as high (1.0 mm) as long (0.5 mm), contacting
prenasal, prefrontals, loreal, and second pair
of supralabials; moderately long loreal (2.3
mm long and 0.9 mm high); loreal contacting
eyes, prefrontals, nasals, and second to third
supralabials; eye diameter 1.1 mm; pupil
round; two postoculars, upper postocular
pentagonal and slightly higher (0.8 mm) than
lower postocular, contacting eye, supraocular,
parietal and anterior temporal, lower post-
ocular slightly longer (0.7 mm) than upper,
contacting eye, fourth and fifth supralabial
and anterior temporal; 1þ2 temporals; anteri-
or temporal longer (1.5 mm) than high (0.9
mm), contacting parietal, fifth to sixth supra-
labials, postoculars, and posterior temporals;
upper posterior temporal elongate (3.4 mm
long), approximately four times longer than
wide; lower posterior temporals not fused and
similar in size and shape to anterior temporal;
seven supralabials, third and fourth contacting
orbit; second supralabial higher than first and
lower than third; sixth supralabial higher and
seventh supralabial longer than remaining
supralabials; symphisial triangular, approxi-
mately twice wider (1.3 mm) than long (0.4
mm); seven infralabials, first three pairs
contacting chinshields; first pair of infralabials
in contact behind symphisial, preventing
symphisial/chinshield contact; chinshields ap-
proximately four times as long (3.6 mm) as
wide (1.2 mm); 17-17-17 smooth dorsal scales
rows, lacking apical pits and supra-anal
tubercles; three gular scale rows between last
supralabial and preventral; three preventral
scales; 147 ventral scales; anal plate single; 36
subcaudal scales. Maxilla arched in dorsal
view, curved on anterior and flattened on
median to posterior portion; maxillary arch
with six prediastemal and single postdiastemal
teeth; prediastemal teeth angular in cross
section, robust at base, narrower at apices,
curved posteriorly; first five teeth large,
moderately spaced, similar in size; sixth
prediastemal tooth reduced in size; maxillary
diastema moderate, with space shorter than
distance between fifth and sixth teeth; post-
diastemal tooth slightly smaller than sixth
prediastemal one; lateral process of maxilla
poorly developed.
Coloration in Preservative of Neotype.—
Dorsum of head uniform brown to posterior
region of parietals; latero-posterior portion of
parietals and temporal region pale brown,
forming a barely distinct incomplete light
band; head background brown to dorsal
margin of supralabials, except for pale brown
spots on temporal region; anterior temporal
with pale brown spots; lower posterior tem-
poral and posterior portion of seventh supra-
FIG. 3.—Dorsal (A), lateral (B), and ventral (C) views of
head of the Atractus microrhynchus (MUSM 22829).
380 [Vol. 68, No. 3
labial creamy, constituting dorsal limits of
dark postorbital stripe; supralabials mostly
creamy, with invasion of brown pigment on
posterior suture between scales; brown post-
orbital stripe crossing posterior region of sixth
and mid portion of seventh supralabial,
forming the descending portion of stripe;
infralabials mostly creamy with brown dots
toward the center or posterior edges of some
scales; mental region creamy with few brown
dots on anterior portion of chinshields; gular
series and preventrals with small irregular
brown marks; ventral ground color creamy
scattered with dark brown marks; first 40
ventrals predominantly creamy with few
brown irregular dots disposed toward the side
of the scales; after that point dots concentrat-
ed laterally forming irregular brown blotches
on lateral region of ventral scales, except for
lateral-most edge of ventrals creamy; brown
dots concentrated toward posterior region of
body; creamy paraventral margin evident
along all of body; ventral surface of tail dark
brown suffused with few creamy dots concen-
trated on margins of subcaudals. Dorsal
ground color light brown with 44 well-defined
paired dark brown blotches (one scale long);
blotches with indistinct creamy borders and
disposed almost linearly on each side of
paravertebral region, extending from fourth
to fifth or fifth to sixth dorsal scale rows; first
dorsal scale rows with invasion of creamy
pigment on each side of body (Fig. 1).
Color Variation.—The color pattern of the
other Ecuadorian specimen is highly similar to
that of the neotype, except that the lowest
dorsal blotches are closer to each other, at
some points forming a discrete lateral broken
line; also the posterior half of the venter is
darker, becoming almost completely dark
brown because of the accumulation of dark
dots; and the ventral surface of tail is
completely dark brown. Peruvian specimens
of A. microrhynchus are similar to the
neotype, with MUSM 22829 differing from it
in the following aspects: distinct occipital light
band, with entire lateral portion of parietals
and first dorsal series pale brown; dark brown
descending stripe and brown marks between
supralabials and infralabials sutures more
conspicuous; first 30 ventral scales more
scattered with brown dots; creamy paraventral
margin evident along all of body; posterior
region of venter with more invasion of creamy
blotches; creamy pigment on ventral surface
of tail reaching median subcaudal sutures;
dorsum with 44/46 (right and left sides,
respectively) well-defined paired black blotch-
es (two to three scales long and one to three
scales high); blotches well spaced in the first
half of body (interspaces three to four scales
long) and next to each other (interspaces one
to two scales long) in the posterior region;
blotches pale brown bordered (half to one
scale wide), covering five to seven dorsal scale
rows (Figs. 2 and 3).
Hemipenial Variation.—Retracted organ
bifurcates at eighth and extends to the level
of 15th subcaudal. Hemipenis strongly bi-
lobed, slightly semicapitate, and semicalycu-
late; lobes clearly distinct from capitulum and
longer than hemipenial body on sulcate and
similar in size to it on asulcate side; lobes
attenuate, centrifugally oriented, with round-
ed apices; left lobe longer than right; lobes
covered with moderate alary spines on basal
portion and concentrated spinulate calyces
from the base increasing toward apices of
lobes; lobes of asulcate side of hemipenis
forming barely defined longitudinal crests;
capitular groove indistinct on sulcate, evident
on lateral region, and barely distinct on
asulcate side of organ; capitulum located
above bifurcation of sulcus spermaticus;
capitulum entirely retracted on asulcate side
of hemipenis and longer than hemipenial
body on sulcate side; capitulum with inverted
‘‘V’’ shape on sulcate to asulcate side; intra-
sulcar region of capitulum with four enlarged,
narrow, hooked spines disposed in longitudi-
nal series; nonlobular portion of capitulum
with spinulate calyces and moderate alary
spines; sulcus spermaticus bifurcates on basal
portion of hemipenial body; after sulcus
spermaticus division three large hooked
spines, on each side of sulcus spermaticus
ramus, delimit the proximal margin of capit-
ular crotch; branches of sulcus spermaticus
centrolinearly oriented, running to tips of
lobes; sulcus spermaticus margins stout and
moderately expanded before lobes division
and widely expanded along each lobe; sulcus
spermaticus bordered with spinules from
basal portion of organ to lobular region;
September 2012] 381
asulcate side of organ with two large hooked
spines just above division of lobes; four large
hooked spines disposed in inverted ‘‘V’’ shape
delimit the capitulum border on asulcate to
lateral side of hemipenis; hemipenial body
subelliptical, uniformly covered with moder-
ate hooked spines; basal naked pocket absent;
basal portion of hemipenis uniformly covered
with longitudinal plicae. The hemipenis of
MUSM 22830 is very similar to that of MUSM
22829, differing from it in the following
aspects: lobes with similar length; eight
enlarged, narrow, hooked spines on intra-
sulcar region; large hooked spines bordering
capitulum on lateral and asulcate side of organ
relatively smaller (Fig. 4).
Quantitative Variation.—Ecuadorian and
Peruvian specimens have seven supralabials,
third and fourth contacting orbit; seven
infralabials, first three contacting chinshields;
three gular scale rows; three preventrals; two
postoculars; and 1þ2 temporals. Variation
occurs in the number of maxillary teeth; the
second Ecuadorian specimen has 6þ1 maxil-
lary teeth on its left side, like the neotype, but
it has 5þ1 maxillary teeth on its right side,
similar to the Peruvian specimens. Juvenile
male (AMNH 108943): 146 mm SVL, 57 mm
TL; 143 ventrals, 35 subcaudals. Adult male
(MUSM 22829): 293 mm SVL, 53 mm TL; tail
18.1% of SVL, 150 ventrals, 34 subcaudals,
retracted hemipenis extends to the level of
15th subcaudal. Adult male (MUSM 22830):
288 mm SVL, 52 mm TL; tail 18% of SVL, 146
ventrals, 32/33 subcaudals, retracted hemi-
penis extends to the level of 13th subcaudal.
Distribution.—Pacific lowlands from central
western Ecuador to northwestern Peru.
Known from three localities in Ecuador:
Guayaquil, Guayas Province; R
ıo Palenque,
Los R
ıos Province; and Buenaventura, El Oro
Province; and one locality in Peru: Cerros de
Amotape National Park, Tumbes region, Peru.
Atractus microrhynchus is apparently endem-
ic to Seasonal Evergreen Forests in the West
Ecuadorian Region, where it is known to
occur between 0- and 800-m elevation (Fig.
5). The West Ecuadorian Region is a biogeo-
graphic zone recently defined for the highly
Seasonal Evergreen Forests that extend along
the Pacific lowlands and foothills of the
Andean Cordillera Occidental in western
Ecuador and extreme northwestern Peru.
Previously considered just as a transition zone
between the Chocoan and Tumbesian biogeo-
graphic regions, recent studies have revealed
that several endemic species of animals and
plants are restricted to this region (Cisneros-
Heredia, 2006, 2007; Cisneros-Heredia and
noz, 2007). The West Ecuadorian
FIG. 4.—Sulcate (left) and asulcate (right) sides of the hemipenis of the holotype of Atractus microrhynchus (A)
MUSM 22829 and (B) MUSM 22830.
382 [Vol. 68, No. 3
Region was originally thought to be confined
to western Ecuador (see Cisneros-Heredia,
2006), but it also includes the small area
reported as Equatorial Dry Forests by Brack
(1986) in the Tumbes area. The original type
locality of A. microrhynchus was reported by
Cope (1868) as Guayaquil, which seems to be
correct. At the time of the Orton Expedition,
the port city of Guayaquil was surrounded by
hills covered with Seasonal Evergreen For-
ests. Guayaquil is between R
ıo Palenque (190
km away) and Buenaventura (150 km away);
both R
ıo Palenque and Guayaquil are located
in the Guayas–Daule–Babahoyo rivers basin.
Remarks.—Unfortunately, the holotype of
A. microrhynchus is lost. To complicate
matters, the original description provided by
Cope (1868) was brief, without any illustration
of the holotype, and no additional species of
Atractus other than A. multicinctus and A.
paucidens Despax, 1910 have been reported
on the Pacific lowlands of Ecuador (Savage,
1960; Passos et al., 2009e). That Cope (1870),
in a subsequent study, reported a supposed
specimen of A. microrhynchus from Pebas in
Peruvian Amazonia suggests that a population
with a color pattern similar to that of A.
microrhynchus occurs in the upper Amazon
basin. Regrettably, this specimen from Pebas
was never catalogued in the Academy of
Natural Sciences of Philadelphia and is also
currently lost (N. Gilmore, personal observa-
tion). Dixon and Soini (1977, 1986) indicated
that 50% of the specimens they referred to A.
cf. microrhynchus exactly match Cope’s orig-
inal description. In this matter we disagree,
and we quote Cope’s description of coloration
for later comparisons: ‘‘Coloration like that of
Tantilla Baird and Girard, 1853. Above dark
brown, beneath pale brown, with a faint line
along the margins of the gastrosteges. Top of
head blackish, brown behind; a partially
complete yellow collar, which widens at the
angle of the jaws. A deep brown band from
eye to angle of mouth; upper labials yellow
brown edged.’’
Passos et al. (2009e) pointed out that the
original description of A. microrhynchus is
inadequate to distinguish it from many
Atractus that have 17 scale rows and a
uniform body color pattern. Cope’s mention
of a dark brown cephalic cap with an
incomplete yellow collar, nearly uniform
dorsum, and belly with lines on lateral region
FIG. 5.—Geographical distribution of Atractus microrhynchus. The solid square represents the original locality of the
holotype of A. microrhynchus from Cope (1868), and the open square represents the current type locality of the A.
microrhynchus. Triangles represent the additional records of A. microrhynchus.
September 2012] 383
of ventral scales led Passos et al. (2009e) to
speculate that A. microrhynchus was perhaps
morphologically similar to A. collaris Peracca,
1897 and other apparently related species (but
see Prudente and Passos, 2008, 2010). How-
ever, all of these features in the specimens
found in the Pacific lowlands of Ecuador and
Peru are only superficially similar to A. collaris
(sensu stricto). In fact, A. microrhynchus as
defined herein differs from A. collaris and
their relatives in several aspects (e.g., in
lacking apical pits and supra-anal tubercles
in males, incomplete and conspicuous occip-
ital white band, conspicuous lateral black
stripes on lateral portion of belly and distinct
postorbital stripe).
Ken Miyata and Frances Irish identified in
July 1979 a specimen of Atractus (AMNH
108943) collected on the Pacific coast of
Ecuador as belonging to A. microrhynchus.
Unfortunately, because of Ken Miyata’s death,
they never published their discovery. In 2002,
one of us (DC-H) examined that specimen
and its accompanying notes written by K.
Miyata and F. Irish; that specimen is clearly
conspecific with the specimens found recently
in other localities of the Pacific lowlands of
Ecuador and Peru. The examination of
recently obtained specimens on the Pacific
lowlands of Ecuador and Peru corroborates
Cope’s description, and Miyata and Irish’s
identification allows us to associate them with
A. microrhynchus. The specimens reported
herein have a dark brown cephalic cap
interrupted on the parietal region by cream
transversal bands without contact in midline
and a more (DHMECN 3008, AMNH
108943, and MUSM 22830) or less (MUSM
22829) distinct paler band on the occipital
region of the head; one of the individuals
(MUSM 22829) has a nearly uniform pale
brown dorsum, whereas the others have
distinct black blotches; all specimens have
cream ventral ground color with well-defined
irregular brown marks interrupted on the
lateral portion of each ventral scale, forming
barely defined paraventral lines (better de-
scribed as cream lateral area by interruption
of dark paraventral blotches) and a conspicu-
ous postorbital black stripe reaching last
supralabials (Figs. 2 and 3). The only feature
in disagreement with the original description
is the number of infralabials contacting
chinshields (three on the new specimens).
Even though the holotype of A. microrhyn-
chus might indeed be unusual among Atractus
in having two infralabials in contact with the
chinshields, we also are aware of the possibil-
ity that Cope did not count the first pair of
scales behind the symphysial as infralabials (a
usual Atractus feature; see Passos et al.,
2009e). Because of the complex taxonomic
history of A. microrhynchus discussed above
and the difficulties that many authors have
had in recognizing this species after its
original description (including Cope), we
believe that a neotype designation is required
to clarify the taxonomic status of the species.
In doing so, we follow all qualifying conditions
of article 75.3 of the ICZN (1999), and we
select the specimen that is closest to the type
locality as the neotype of A. microrhynchus.
Atractus natans Hoogmoed and Prudente, 2003
(Figs. 6–8; Table 1)
Atractus badius Dixon and Soini, 1977;
Milwaukee Publ. Mus. Contrib. Biol. Geol.
Atractus cf. microrhynchus Dixon and
Soini, 1986; Milwaukee Public Museum.
Atractus sp. Bartlett and Bartlett, 2003: Fig.
205B (photograph of a specimen in life).
Atractus natans Hoogmoed and Prudente,
2003; Zool. M
ed. Leiden 77:428.
Atractus emersoni Silva, 2004; Rev. Acad.
Col. Cien. Exa. Fis. Nat. 108:423. New
Holotype.—Adult female, MPEG 18836,
collected on 1 August 1994 by M. S.
Hoogmoed and T. C.
Avila-Pires near conflu-
ence of Apara and Mamiraua
rivers (03802
W, sea level), Esta¸ca
o Ecol
ogica de
, Melga¸co, state of Para
(specimen examined).
Paratypes.—Juvenile female (MPEG
18838), same data as holotype; adult female
(RMNH 35530), sand bank on the left margin
of Rio Mamiraua
S, 64848
W, sea
level), Esta¸ca
ogica de Mamiraua
Melga¸co; adult female (MPEG 20213), Esta-
ıca Ferreira Penna (01843
W, sea level), FLONA de Caixuana
Rio Curua
, Melga¸co (all specimens examined
except RMNH 35530).
384 [Vol. 68, No. 3
Referred specimens.—Adult females, ICN
10097 (holotype of A. emersoni) and ICN
10098 (paratype of A. emersoni) collected May
2001 at locality of Boa Vista, Municipality of
Benjamin Constant (04825
S, 70802
W, ca. 65
m asl), Brazil; adult male ICN 10099 (para-
type of A. emersoni) collected at Quebrada de
los Lagos, Municipality of Leticia (04813
W, ca. 83 m asl), Colombia; and
subadult ICN not catalogued, from unknown
locality, but apparently donated by J. S. Haad
from Colombian Amazonia (J. D. Lynch,
personal observation). Sixteen specimens all
from department of Loreto in Peru: Iquitos
S, 73814
W, ca. 100 m asl):
TCWC 39063; Zona Reservada Allpahuayo-
Mishana (ca. 03853
S, 73827
W, 100 m asl):
TCWC 42792–801, 47803–04, MCZ 151769;
on (ca. 03827
S, 73832
W, ca. 100 m
asl): TCWC 39064; R
ıo Maniti: TCWC 52502.
Diagnosis.—Atractus natans is distin-
guished from all congeners by the following
combination of characters: (1) 17-17-17
smooth dorsals; (2) usually two postoculars;
(3) moderately long loreal; (4) temporals 1þ2;
(5) usually seven supralabials, third and fourth
contacting orbit; (6) usually seven infralabials,
first four contacting chinshields; (7) five or six
maxillary teeth; (8) four gular scale rows; (9)
usually four preventrals; (10) 154–163 ventrals
in females, 136–152 in males; (11) 18–26
subcaudals in females, 23–31 in males; (12)
dorsum dark brown to black generally with
distinct irregular black blotches on flanks,
juveniles and subadults with cream occipital
band; (13) venter mostly black, with lateral
region of ventral scales paler (beige to
creamish brown); (14) moderate body size in
females (390 mm SVL), small (250 mm SVL)
in males; and (15) short tail in females (8.8–
10.6% of SVL), moderate long (13.5–15.2% of
SVL) in males.
Comparisons.—Among all congeners, A.
natans shares just with A. tamessari Kok,
2006 ca. 154–163 ventrals in females, four
infralabials contacting chinshields, dorsum
dark brown to black with dots or blotches on
the flanks, venter mostly black, and five to six
maxillary teeth. Atractus natans differs from
A. tamessari in having 17 dorsal scale rows,
FIG. 6.—Dorsal (A) and ventral (B) views of the
specimen of Atractus natans (TCWC 42800) from
Mishana, department of Loreto, Peru.
FIG. 7.—Dorsal view of the holotype of Atractus emersoni (ICN 10097).
September 2012] 385
seven supralabials, paler occipital band in
juveniles and subadults, dorsum usually with
distinct dorsal blotches white bordered (vs. 15
dorsal scale rows, usually eight supralabials,
lacking paler occipital band, dorsum generally
uniform black, occasionally scattered with
irregular red dots).
Description.—Head approximately twice as
long as wide, flattened in lateral view and
rounded in dorsal view; slightly distinct from
body; snout truncate in lateral view, slightly
rounded in dorsal view; rostral subtriangular
in frontal view, visible in dorsal view, approx-
imately twice as wide as high; internasal wider
than long; internasal suture sinistral with
respect to prefrontal suture; prefrontal ap-
proximately as long as wide; supraocular
subrectangular, approximately twice as long
as wide; frontal pentagonal or subtriangular,
as long as wide; parietal approximately twice
longer than wide; nasal divided; nostril located
between prenasal and postnasal; prenasal two
or three times as high as long, contacting
rostral, internasal, first supralabial, and post-
nasal; postnasal as long as wide, contacting
prenasal, prefrontals, loreal, and second pair
of supralabials; moderately long loreal; loreal
contacting eyes, prefrontals, nasals, and sec-
ond to third supralabials; pupil round; usually
two postoculars; upper postocular slightly
longer, and lower slightly higher; temporals
1þ2; anterior temporal twice as long as high,
contacting parietal, fifth to sixth supralabials,
postoculars, and posterior temporals; upper
posterior temporals fused, shield four times
longer than wide; seven supralabials, third and
fourth contacting orbit; second supralabial
higher than first and smaller than third; sixth
higher and seventh longer than remaining
supralabials; symphisial semicircular, approx-
imately six times as wide as long; seven
infralabials, first four pairs contacting chin-
shields; first pair of infralabials in contact
behind symphisial, preventing symphisial/
chinshield contact; chin shields twice as long
as wide; four gular scale rows; usually four
preventrals; 17-17-17 dorsal scale rows, lack-
ing apical pits and supra-anal tubercles;
caudal spine moderately long, conical, and
slightly acuminate. Maxilla arched in dorsal
view, with four or five prediastemal and two
postdiastemal teeth; prediastemal teeth angu-
lar in cross section, robust at base, narrower at
apices, curved posteriorly; first five teeth
large, moderately spaced, decreasing gradual-
ly in size posteriorly; maxillary diastema short,
FIG. 8.—Dorsal (A) and ventral (B) views of the paratype of Atractus emersoni (ICN 10098).
TABLE 1.—Variation in the meristic characters of the Atractus natans. Samples referred below as Atractus emersoni and
Atractus natans represent the type series for each taxon respectively, and specimens from the Iquitos region, previously
identified as A. badius (Dixon and Soini, 1977) or A. cf. microrhynchus (Dixon and Soini, 1986), also are A. natans as
defined here.
Sample Sex Ventrals Subcaudals Supralabials Infralabials Infralabials contacting chinshields Maxillary teeth
A. natans Male n ¼ 1 136 23 7 7 4 5–6
Female n¼2 158–163 19–21
A. emersoni Male n ¼ 1 146 29 7 7 4 5
Female n ¼ 2 155–156 21–23
Iquitos region Male n ¼ 10 144–152 25–31 7 7 4 5–6
Female n ¼ 6 159–162 18–26
386 [Vol. 68, No. 3
with space equivalent to size of fifth predias-
temal tooth; postdiastemal teeth half size of
fifth prediastemal tooth; lateral process of
maxilla poorly developed.
Juvenile Color in Preservative.—Dorsum of
head dark brown to black, except for snout
(rostral, internasals, and anterior portion of
prefrontals) and occipital band (usually com-
plete) cream to light brown; large occipital
band, reaching anterior region of parietals,
posterior temporals, and occipital scales;
background of head dark brown to black with
snout region (rostral, nasals, and loreal) cream
to light brown; anterior supralabials (first and
second) cream, remaining supralabials mostly
black with cream dots concentrated on
anterior portion of each scale; infralabials
and chinshields usually black, with little
invasion of pale pigment (creamish yellow to
brown); gular region creamish yellow scat-
tered with black dots; venter usually cream
anteriorly, scattered with disperse dark brown
dots or blotches; mid to posterior region of
belly tends to become uniformly black by
collapsing black blotches on median region of
ventral scales; ventral surface of tail uniformly
black; dorsal ground color of body dark brown
with 40–60 irregular black blotches pale
(cream to light brown) on flanks; irregular
blotches (one or two scales long) covering fifth
to sixth dorsal scale rows; first three dorsal
scale rows occasionally with dispersed black
dots (half or one scale long); first dorsal scale
row beige to pale brown, usually with
reticulate pattern of cream below black dots.
Adult Color in Preservative.—Adults with
snout and occipital pale regions of head
darker than juvenile (beige to dark brown);
belly mostly black, except at lateral margin of
ventral scales creamish brown to beige;
dorsum usually uniformly black or with poorly
distinct blotches along body.
Color in Life.—Dorsal ground color of body
black to dark reddish brown, usually with
black pale (light reddish) bordered blotches;
mental region cream, with pale reddish brown
irregular blotches; belly mostly black, with
lateral margins of ventral scales pale brown
(beige); median to posterior region of belly
uniformly black.
Hemipenis.—Retracted organ bifurcates at
sixth and extends to level of seventh sub-
caudal. Hemipenis moderately bilobed, barely
semicapitate, and semicalyculate; lobes dis-
tinct and restricted to distal region of capit-
ulum; lobes approximately conical, with
distinct length; right lobe (same side of naked
pocket) always longer than left; lobes slightly
smaller than proximal region of capitulum;
capitulum uniformly covered with concentrat-
ed spinulate calyces; capitular crotch evident
on both sides of hemipenis, more developed
on asulcate and barely defined on sulcate side
of organ; capitulum located below sulcus
spermaticus bifurcation, delimited on proxi-
mal region by moderate hooks; capitulum
slightly retracted on median region of asulcate
side and equivalent to hemipenial body on
sulcate side of hemipenis; sulcus spermaticus
divides on middle of organ above distal
portion of hemipenial body; sulcus spermati-
cus branches centrifugally oriented, reaches
apices of lobes; margins of sulcus spermaticus
narrow and stout, bordered with spinules from
base to tip of lobes; hemipenial body sub-
cilindrical, uniformly covered with small to
moderate hooked spines; largest spines con-
centrated on lateral region of sulcate and
medial portion of asulcate side adjacent to
capitulum; basal naked pocket located in the
right side of organ, extending to proximal
region of hemipenial body; basal region of
hemipenis with longitudinal plicae and dis-
persed spinules.
Quantitative Variation.—Largest males 250
mm SVL, 38 mm TL; largest female 385 mm
SVL, 41 mm TL; tail 13.5–15.2% (n ¼ 2) of
SVL in males, 8.8–10.6% (
X¼9.8, SD¼0.75; n
¼ 4) of SVL in females; 136–152 (
X ¼ 144.5,
SD¼6.6; n ¼4) ventrals in males, 154–163 (
¼158.1, SD ¼3.4; n ¼7) in females; 23–31 (
¼ 27.2, SD ¼ 3.6; n ¼ 4) subcaudals in males,
18–26 (
X ¼21.5, SD ¼2.7; n ¼7) in females; 7
(n ¼44 sides) or 8 (n ¼2 sides) supralabials; 7
(n ¼44 sides) or 8 (n ¼2 sides) infralabials; 1
(n ¼4 sides) or 2 (n ¼42 sides) postoculars; 3
(n ¼ 1) or 4 (n ¼ 6) preventrals; 6–9 (
X ¼ 7.9,
SD ¼0.7; n ¼14 sides) dorsal scale rows at the
level of second subcaudal; 5 (n ¼11 sides) or 6
(n ¼ 3 sides) maxillary teeth; retracted hemi-
penis extends to the level of sixth or seventh
subcaudal (n ¼2).
Distribution.—Amazon rainforest south to
the Amazon River, from Mishana (03847
September 2012] 387
W) department of Loreto, Peru, east to
Melga¸co (01847
S, 50844
W), state of Para
Brazil. Atractus natans occurs from sea level
to 100-m elevation (Fig. 9).
Remarks.—Although Cope’s description of
A. microrhynchus was brief, there are notable
differences between it and characteristics of
the specimens from Iquitos previously re-
ferred to Atractus badius (Dixon and Soini,
1977) or Atractus cf. microrhynchus (Dixon
and Soini, 1986). Most notably, Cope (1868)
did not mention any pattern overlaid on the
brown dorsal coloration of A. microrhynchus.
That he described the coloration of A. micro-
rhynchus as ‘‘like that of Tantilla’’ may
indicate as well that the dorsal coloration of
the holotype of A. microrhynchus was uniform
brown (with a black cephalic cap) as in many
species of Tantilla. However, the presence of
black blotches on the flanks is variable (more
or less conspicuous) among the specimens
herein referred to A. microrhynchus, and also
in the Amazonian populations of A. natans
(Hoogmoed and Prudente, 2003) and A.
emersoni (Silva, 2004; present study). As such,
there are two possibilities: (1) the holotype of
A. microrhynchus also would have barely
distinct dorsal blotches as in MUSM 22829
(Fig. 2A) or (2) the specimen reported by
Cope (1870) was uniformly dark brown or
black, as are many individuals of A. natans and
A. emersoni (Hoogmoed and Prudente, 2003;
Fig. 7). This last possibility of melanistic
individuals in the Amazon basin better ex-
plains why Cope (1870) referred another
specimen to A. microrhynchus if the later
was apparently not blotched.
The ventral coloration of A. microrhynchus,
as described by Cope (1868), also differs from
that observed in the specimens from the
Amazon basin. In the latter specimens, the
venter is usually black in the middle, with a
cream lateral area or with dispersed blotches
on the anterior region of belly (Figs. 6–8),
whereas A. microrhynchus has a cream venter
with irregular pale brown marks not collapsed
in the middle of the belly at least on the
anterior and mid portions of the body (Figs.
1–3). Although the specimens from the
Amazon basin often have some dark spots or
blotches in the postocular region, these spots
never form a stripe as described by Cope in A.
microrhynchus (Figs. 6–8), which was likely
conspicuous and well defined to be noted by
Cope in his brief description. Based on the
above-mentioned observations, we consider
the specimens from Iquitos, herein referred to
A. emersoni or A. natans (see below), to be
different from A. microrhynchus. The less
likely possibilities that Cope’s description of
FIG. 9.—Geographical distribution of Atractus natans. Open squares represent the type locality of the species.
388 [Vol. 68, No. 3
A. microrhynchus is inaccurate in terms of
coloration, and that the type locality is in error
(as has apparently been noted with other
material from the Orton expedition), are not
supported (see Passos et al., 2009e, for
additional comments in this respect).
The examination of the type series and
additional specimens of A. emersoni and A.
natans revealed that all meristic, morphomet-
ric, color pattern, and hemipenial features
largely overlap; the variation in these species
also overlaps that of the specimens previously
reported by Dixon and Soini (1977, 1986)
from the Iquitos region (Table 1). Whereas
mature individuals of A. natans usually display
a melanistic pattern with barely distinct
blotches that differ from the holotype of A.
emersoni (a subadult specimen), a paratype of
A. emersoni (ICN 10099) shows poorly
distinct blotches on the dorsum like those on
the holotype of A. natans (Hoogmoed and
Prudente, 2003; Figs. 6–8). Although Silva
(2004) did not describe a pale occipital band
in the juvenile specimens of A. emersoni,
examination of the type series of the species
revealed the presence of a darker pale (beige)
band on the occipital region and also conspic-
uous pale blotches on the snout region of A.
emersoni (Figs. 6–8); both characteristics are
evident in most individuals of A. natans (see
Hoogmoed and Prudente, 2003). Apparently,
the minor or major contrast between the
occipital band and ground color is correlated
with ontogenetic changes of coloration or
melanism (this question cannot be addressed
with the available sample). Even so, according
to our sample, adults of both species tend to
become darker in the course of their ontog-
eny. Furthermore, the hemipenis description
of A. emersoni provided by Silva (2004: Fig.
23) was not accurate with respect to capitation
structures. The examination of this organ
revealed that it is in fact semicapitate and
semicalyculate (sensu Zaher, 1999), as was
described by Hoogmoed and Prudente (2003:
434, 436) for A. natans. Finally, as found for
most Amazonian congeners (Hoogmoed,
1980; Cunha and Nascimento, 1983; Martins
and Oliveira, 1993; Passos and Fernandes,
2008; Prudente and Passos, 2008), A. natans
also has a wide range of distribution along the
biome (see Hoogmoed and Prudente, 2003).
Therefore, for the reasons discussed, A.
emersoni is herein relegated to the synonymy
of A. natans.
Passos et al. (2009e) proposed the A.
multicinctus species group to accommodate
Pacific lowland Atractus that share a unique
combination of morphological characters for
the genus. They pointed out that the strongly
bilobed hemipenis and the basal bifurcation of
the sulcus spermaticus might constitute de-
rived character states in the evolution of
certain species of the ‘‘goo-eaters’’ clade of
the Dipsadini (P. Passos, personal observa-
tion). Atractus microrhynchus shares both
hemipenial conditions, as well as the presence
of narrow, enlongated, hooked spines in the
intrasulcar region, with members of the A.
multicinctus species group (A. boulengerii
Peracca, 1896; A. clarki Dunn and Bailey,
1939; A. medusa Passos, et al., 2009e; and A.
multicinctus). However, in terms of external
morphological characteristics (meristic, mor-
phometric, and color pattern traits), A. micro-
rhynchus is most similar to the Andean A.
dunni, A. ecuadoriensis,andA. occidentalis,
and to the Pacific lowland A. echidna and A.
iridescens (last two from the lowland A.
paucidens species group).
In fact, using the key for Pacific lowland
Atractus provided by Passos et al. (2009e), A.
microrhynchus falls at the sixth step in the
key. However, A. microrhynchus differs from
A. iridescens and A. paucidens (alternative
steps in that dichotomy) in the number of
ventral scales; however, see the comparisons
section of this study for additional diagnostic
characters among these taxa. Although A.
microrhynchus is morphologically most simi-
lar to the Andean A. dunni, A. ecuadoriensis,
and A. occidentalis, the taxonomic status of
the latter forms will be discussed in a
subsequent paper. Most of the external
morphological characters shared by A. micro-
rhynchus and the aforementioned taxa are
widespread and likely homoplastic features
(e.g., color pattern and relative tail size) that
may occur individually or in some combina-
tion in several other species or species groups
in the genus. Because a robust phylogenetic
hypothesis is still lacking for Atractus, at this
September 2012] 389
moment we prefer to use the hemipenial
features to infer the putative affinities of A.
microrhynchus. Therefore, we allocate A.
microrhynchus to the A. multicinctus species
group on the basis of shared unusual hemi-
penial characters such as strongly bilobed
organ; basal bifurcation of the sulcus sperma-
ticus; and the presence of elongated, narrow,
hooked spines in the intrasulcar region.
Finally, because there are ongoing taxonomic
studies on the Amazonian species of Atractus,
we refrain from allocating A. natans to the
currently proposed species groups.
Acknowledgments.—We are deeply indebted to N.
Gilmore (ANSP) for information about the holotype of
R. microrhynchum and about specimens collected by the
Orton Expedition in Amazon basin. We thank F. Sornoza
and the Jocotoco Foundation for collecting the neotype of
the A. microrhynchus and allowing access to the
Buenaventura reserve; H. Ya
noz for sharing
information on the type locality; and R. Cadenillas and
V. Pacheco for collecting the Peruvian specimens of A.
microrhynchus and sharing field data. We thank three
anonymous reviewers for commentaries and suggestions
on an early version of the manuscript. We thank the
following curators (in alphabetical order) for allowing
examination of specimens under their care: J. C
(MUSM), J. Dixon and L. Fitzgerald (TCWC), J. Lynch
(ICN), A. Prudente (MPEG), and M. H. Ya
(DHMECN). For financial support, PP is grateful to
Conselho Nacional de Desenvolvimento Cient
ıfico e
ogico (CNPq), Pr
o-Reitoria de P
Pesquisa da Universidade Federal do Rio de Janeiro (PR-
2/UFRJ), Funda¸ca
o de Amparo
a Pesquisa do Estado de
o Paulo (FAPESP; process 2011/50313-0), and Funda-
o Carlos Chagas de Amparo
a Pesquisa do Estado do Rio
de Janeiro (FAPERJ) for financial support; and DC-H is
grateful to Ma. Elena Heredia, Laura Heredia, the
Research Training Program/Smithsonian Women’s Com-
mittee of the National Museum of Natural History
(Smithsonian Institution), and the Russell E. Train
Education for Nature Program of the World Wildlife
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Accepted: 17 May 2012
Associate Editor: Christopher Raxworthy
392 [Vol. 68, No. 3
... Although our knowledge of the diversity and natural history of reptiles in western Ecuador is limited, important herpetological discoveries have been made in recent years, such as new species and significant expansion of the geographic range extensions of previously recorded species (e.g. Jadin et al. 2009;Cisneros-Heredia et al. 2010;Ortega-Andrade et al. 2010;Passos et al. 2012;Torres-Carvajal et al. 2012, 2015Ayala-Varela et al. 2014;Yánez-Muñoz et al. 2014Cisneros-Heredia and Romero 2015;Pyron et al. 2015;Salazar-Valenzuela et al. 2015;Cruz-García 2017;Cruz et al. 2017;Arteaga et al. 2017Arteaga et al. , 2018Reyes-Puig et al. 2019). ...
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Southernmost record of Rhinobothryum bovallii (Andersson 1916), new country records and notes of distribution range of Anolis lyra (Poe, Velasco, Miyata and Williams 2009), Corallus blombergi (Rendahl and Vestergren 1941) and, Spilotes megalolepis (Linnaeus 1758), are provided from specimens collected in Cerro de Hayas forest, Guayas province, southwestern Ecuador.
... Ecuatoriano de Ciencias Naturales (DHMECN), Instituto Nacional de Biodiversidad, Quito Ecuador; Museo de Historia Natural de la Escuela Politécnica Nacional (MEPN), Quito, Ecuador; Museo de Zoología, Pontificia Universidad Católica del Ecuador (QCAZ), Quito, Ecuador; and Fundación Herpetológica Gustavo Orcés (FHGO), Quito, Ecuador. Comparative material of Atractus gigas and Atractus touzeti is listed in Appendix I, while additional congeners examined are listed in Passos et al. (2005), Passos et al. (2007a, b), Passos and Fernandes (2008), Passos and Arredondo (2009), Passos et al. (2009a, b, c, d, e), Passos et al. (2010a, b, c), Passos and Lynch (2011), Passos and Prudente (2012), Passos et al. (2012), Passos (2008, 2010), Passos et al. (2013a, b, c, d), Almeida et al. (2014), Salazar-Valenzuela et al. (2014), Passos et al. (2016a, b), de Fraga et al. (2017), and Passos et al. (2017). We provide the authorship and date only in the first mention of each name. ...
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Body-size is significantly correlated with the number of vertebrae (pleomerism) in multiple vertebrate lineages, indicating that somitogenesis process is an important factor dictating evolutionary change associated to phyletic allometry and, consequently, species fitness and diversification. However, the role of the evolution of extreme body sizes (dwarfism and gigantism) remains elusive in snakes, mainly with respect to postnatal ontogeny in dietary preferences associated with evolution of gigantism in many lineages. We described herein a new species in the highly diversified and species-rich genus Atractus on the basis of four specimens from the southeastern slopes of the Ecuadorian Andes. The new species is morphologically similar and apparently closely related to two other allopatric giant congeners (A. gigas and A. touzeti), from which it can be distinguished by their distinct dorsal and ventral coloration, the number of supralabial and infralabial scales, the number of maxillary teeth, and relative width of the head. In addition, we discuss on the ontogenetic trajectories hypotheses and dietary specializations related to evolution of gigantism in the goo-eaters genus Atractus.
... Passos et al. (2009a) included Atractus echidna, A. iridescens and A. microrhynchus in the phenetic A. paucidens species group. Later, Passos et al. (2012) placed A. microrhynchus in the A. multicinctus group based on hemipenial characters. Unlike A. paucidens or A. multicinctus (Jan, 1865), however, the former three species have a brownish color pattern (Fig. 2) and also a lower number of ventral scales (Appendix III). ...
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We present a molecular phylogeny of snake genus Atractus, with an improved taxon sampling that includes 30 of the 140 species currently recognized. The phylogenetic tree supports the existence of at least three new species in the Pacific lowlands and adjacent Andean slopes of the Ecuadorian Andes, which we describe here. A unique combination of molecular, meristic and color pattern characters support the validity of the new species. With the newly acquired data, we propose and define the A. iridescens species group, as well as redefine the A. roulei species group. The species A. iridescens is reported for the first time in Ecuador, whereas A. bocourti and A. medusa are removed from the herpetofauna of this country. We provide the first photographic vouchers of live specimens for A. multicinctus, A. paucidens and A. touzeti, along with photographs of 19 other Ecuadorian Atractus species. The current status of A. occidentalis and A. paucidens is maintained based on the discovery of new material referable to these species. With these changes, the species number reported in Ecuador increases to 27, a number that is likely to increase as material not examined in this work becomes available and included in systematic studies.
We review the Atractus snethlageae species complex based on the examination of 330 specimens throughout its entire distribution, including its type series. We redefine A. snethlageae and recognize four new species previously assigned to it in the literature and natural history collections. Two of them are diagnosed through both phenotypic (meristic, morphometric, color pattern, and male genital structure) and molecular (phylogeny) evidence, while the other two are recognized on the basis of morphological characters only. We show that some Amazonian lowland species have more restricted ranges. The area covering the eastern portion of the state of Pará and western portion of the state of Maranhão in Brazil harbors restricted endemism for Atractus. This biogeographically important region is also the most threatened within Amazonia. Finally, we discuss the expected changes in the taxonomy of ground snakes with more robust hypotheses based on well‐sampled phylogenies. We review the Atractus snethlageae species complex (Serpentes, Dipsadidae) through phenotypic and molecular evidence, and recognize four new species previously assigned to it. We show that some Amazonian lowland species have more restricted ranges on the eastern portion of the biome, which represent one of the most currently threatened area within Amazonia.
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We evaluated the taxonomic status of snakes from the Atractus emmeli species complex (composed by A. boettgeri, A. emmeli, A. paravertebralis, and A. taeniatus) on the basis of concordance between quantitative (meristics and morphometrics) and qualitative (pholidosis, color pattern, and hemipenis) analyses of morphological characters, in combination with ecological niche modeling and niche overlapping. We synonymize A. boettgeri, A. paravertebralis, and A. taeniatus with A. emmeli based on the congruent analytical results. We also describe a new species to accommodate the Brazilian populations from the state of Mato Grosso mainly based upon some unique states of morphological characters, including hemipenial morphology, color pattern, and meristics. We found that the new species has a distinct ecological niche compared with A. emmeli and some level of niche overlapping with A. albuquerquei. We found great differences in ecological niches of species occurring in the Cerrado versus those occurring in the Western Amazon–Andean foothills, suggesting a putative niche evolution in this group.
The Guiana Shield harbours one of the best preserved and largest extents of tropical forest on Earth and an immense biodiversity. The herpetofauna of this region remains poorly known. The species-rich snake genus Atractus contains ∼140 species, many with complicated taxonomic histories, including A. schach. Examination of specimens in museums and newly collected material from French Guiana has allowed the illustration of hemipenial morphology for the first time and an expanded diagnosis. Concatenated molecular phylogenetic (mitochondrial and nuclear genes) and phenotypic (morphometrics, external and hemipenial morphology) analyses confirm non-monophyly of the A. flammigerus group and indicate that A. schach is a species complex with three new species described here. The geographic distribution of A. schach sensu stricto is restricted to Guiana, Surinam, and French Guiana north of Tumucumaque massif. Populations tentatively assigned to A. schach from the east from French Guiana in the Roura lowlands to Almeirim, and from central Amazonia between the Negro and Trombetas rivers in Brazil are also recognized as new species. Our results suggest that populations from south of the Amazon River are not conspecific with those from the Guiana Shield.
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We describe herein a new polychromatic species of the snake genus Atractus from the cloud forests of the northeastern Andes of Colombia. The new species is distinguished from all congeners by having an exclusive combination of phenotypic characters, such as: dorsal scale rows 17, loreal long, seven to ten maxillary teeth, ventrals 156–174 in females and 153–169 in males, subcaudals 20–30 in females and 23–30 in males, dorsum with variable coloration, changing from dark green to orange or red with a black nuchal band (three to four scales long) connected to a black vertebral line and two black dorsolateral continuous stripes from the occipital region to tip of the tail, venter with irregular black blotches, relatively small body size, small tail length in females and moderately long in males, hemipenis moderately bilobed, semicapitate and semicalyculate. We compared the new species with all congeners occurring along the Cordillera Oriental in Colombia, Sierra de Perijá in the Colombia/Venezuela frontier and Cordillera de Mérida in Venezuela. We discussed aspects related to polychromatism and its implication toward a robust taxonomy for the genus Atractus.
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We reassessed the taxonomic status of the species in the Atractus collaris complex (A. alphonsehogei, A. collaris, A. limitaneus, and A. gaigeae) on the basis of congruence between quantitative and qualitative morphological characters (meristic, morphometric, color pattern, hemipenis, and scale microdematoglyphics) along its wide geographical distribution. Our results support the recognition of three species with apparently fixed diagnostic characters. We propose the synonymization of Atractus limitaneus with A. collaris based on the wide overlap of all morphological character systems here analyzed, as well as on the basis of examination of the holotype and two topotypes of A. limitaneus. Finally, we discuss the geographical variation and morphological distinction of A. alphonsehogei, A. collaris and A. gaigeae. Furthermore, we provide a dichotomous key for all recognized species in the A. collaris species group.
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Atractus flammigerus was described on the basis of two specimens from Java (in error). Subsequently, its lectotype was designated and the type locality restricted to Paramaribo in Suriname. Although this species has been repeatedly recorded throughout western Amazonia (mainly from Brazil and Peru), all of these records were erroneously assigned to A. flammigerus because of a considerable level of confusion with two widespread congeners (A. snethlageae and A. torquatus). To date, only nine individuals of A. flammigerus (sensu stricto) are reported in the literature on the basis of vouchered specimens. During the examination of scientific collections and fieldwork we found 12 additional specimens of this poorly known snake, expanding our knowledge on its morphological variability and distribution. In this paper, we report new localities and data on meristic, morphometric, color pattern in life and, after preservation, macro- and micro-ornamentation of dorsal scales, cranial osteology, and hemipenis morphology of A. flammigerus. We provide new diagnostic features and additional data for detailed comparisons with morphologically similar and sympatric congeners, and update the species boundaries of A. flammigerus.
Atractus potschi was described based on 12 specimens from the Brazilian states of Alagoas and Sergipe, and later knowledge of its morphological variation (meristic, morphometric, and color pattern data) was augmented on the basis of nine additional individuals from additional localities in northeastern Brazil. Based on the examination of collections and fieldwork, we found more than 70 additional specimens of Atractus potschi, 60 of them obtained during a single collecting event. In this paper, we report new data on intra-population morphological variation (external morphology, hemipenis, osteology, cephalic glands, and soft anatomy) and natural history for the species. We associate the variation displayed in some characters with sex or age. We relate most of the variation observed in the shape of the hemipenis with preparation artifacts at the moment of preserving specimens. Our results reveal a high level of population polychromatism, supplanting the geographical variability exhibited by this system, while other complexes of morphological characters are relatively conserved both within and among populations. Although this polychromatic pattern seems to be retained in several lineages of Atractus, this phenomenon might be related to distinct life history constrains of the species. On the basis of anecdoctal field data, we discuss the possibility of post-parturition aggregation of juveniles in Atractus potschi. Despite being based on a single observation, this report is significant, since such post-birth interactions in nature (other than reproductive ones) have only been documented previously in temperate regions.
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The taxonomic status ofAtractus sanctaemartae and A. nebularis is revised on the basis of quantitative and qualitativeanalyses of morphological characters (meristics, morphometrics, colour pattern and hemipenis). Characters used previously for diagnosing Atractus nebularis from A. sanctaemartae are demystified, and the synonymy of these species is proposed. Colour pattern, meristic, morphometrical and scale ornamentation differences originally employed in recognizing both taxa are explained as sexually dimorphic characters, which hold no geographic or phylogenetic basis.Additionally, a new species closely related to Atractus sanctaemartae is described from the Atlantic coast of Colombia.It is distinguished from A. sanctaemartae mainly by having two gular scale rows, slender (62% of body diameter) and acuminate head, snout acuminate in lateral view, dorsum uniformly reddish brown and venter cream with a series of rhomboidal blotches arranged linearly on the lateral portion of the ventral scales. We also discuss putative affinities of the new species and A. sanctaemartae on the basis of shared similarity characters, and comment on the occurrence of strong sexually dichromatic coloration in A. sanctaemartae, unique within the genus.
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We present a revision of Atractus in north-eastern Argentina based on the examination of newly collected specimens and most of the material available in Argentinean museums. Four species are reported: A. snethlageae, A. paraguayensis, A. reticulatus and A. taeniatus. Atractus badius was erroneously cited as occurring in Argentina based on a specimen from Las Palmas, Chaco province which is reassigned to A. snethlageae. This record represents a considerable southern extension of the known range of the species. Atractus paraguayensis is redescribed based on three new specimens. This species was previously known only from the holotype reported from 'Paraguay' without definite locality data. Adult and juvenile colour patterns in life are described. The validity of some diagnostic characters is discussed, and new diagnostic characters are given for A. reticulatus and A. paraguayensis. All species examined showed noteworthy variation in colour pattern. Sexual dimorphism is reported in all species. The distributional patterns and phytogeographic areas occupied by each species in Argentina are discussed. We also characterize morphological variation for each and provide a key for the Argentinean species.
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The taxonomic status of the Pacific lowland Atractus is revised on the basis of meristic, morphometric, colour pattern, and hemipenial characters. Geographical variation is reported for six Atractus species (A. boulengerii, A. clarki, A. iridescens, A. melas, A. multicinctus, and A. paucidens). Atractus boulengerii is rediscovered and redescribed from a specimen from the Colombian coast. The first voucher specimens are reported for A. melas. The current status of A. microrhynchus is maintained based on the discovery of new material referrable to that species. Three new species of Atractus are described from the Pacific lowland of Colombia: A. echidna sp. nov., A. medusa sp. nov., A. typhon sp. nov. Two new Atractus species groups (multicinctus and paucidens) are proposed based on external morphology, maxillary dentition, and hemipenial characters. A new key to Pacific lowland species of Atractus is provided.
Two new Andean snakes exhibit extreme morphology in a genus of South American dipsadine colubrids. One, Atractus attenuatus, new species, is a slender, exceptionally attenuated snake 420 mm in total length (adult male holotype), with 17 scale rows, a high ventral + subcaudal count (226), and an extremely vague pattern of numerous, closely spaced, indistinct dark crossbars on a brown ground color. Atractus attenuatus comes from 1000 m elevation in the northern end of the Cordillera Central (Sabanalarga, Antioquia, Colombia). A geographic neighbor, Atractus sanguineus Prado, is of similar morphology but differs in having distinct, widely spaced crossbars on a red ground color. At another extreme, Atractus gigas, new species, is a very robust snake that exceeds a meter in length (adult female holotype 1040 mm in total length), with a hint of pale transverse dorsal bars on a brown ground color. It is the largest known Atractus, differing in color pattern and details of scutellation from the several other congeners that attain lengths > 700 mm. The only known specimen has an azygous frontonasal scale that is atypical of colubrids (but is not an obvious aberrancy). Atractus gigas comes from 1900 m elevation on the Pacific versant of the Andes (Bosque Protector Rio Guajalito, Pichincha, Ecuador).