Pacific lowland snakes of the genus Atractus (Serpentes: Dipsadidae), with description of three new species
Author
Passos, Paulo
Author
Mueses-Cisneros, Jonh Jairo
Author
Lynch, John D.
Author
Fernandes, Ronaldo
text
Zootaxa
2009
2293
1
34
journal article
10.5281/zenodo.191476
8603d4d1-efc8-44bb-84ae-76d3d8dd8161
1175-5326
191476
Atractus boulengerii
Peracca, 1896
Fig. 1
Atractus boulengerii
Peracca, 1896
; Boll. Mus. Zool. Anat. Comp. Torino 11(252):1.
Holotype
:
Adult male, from “
America
Meridionali” (= South
America
), originally deposited in Museo di Zoologia dell’ Università degli Studi di Torino, Turin
MZUT
R1832, now housed at Museo Regionali di Scienze Naturali, Turin (
Andreone & Gavetti 2007
), (specimen examined via photographs).
FIGURE 1.
Dorsal (A) and ventral (B) views of
Atractus boulengerii
(UV-C 6591). SVL 310 mm, CL 52 mm.
Diagnosis:
Atractus boulengerii
is distinguished from all congeners by the combination of the following characters: (1) 17/17/17 smooth dorsals; (2) two postoculars; (3) loreal long; (4) temporals 1+2; (5) seven supralabials, third and fourth contacting orbit; (6) six infralabials, first three contacting chinshields; (7) five maxillary teeth; (8) four gular scale rows; (9) four preventrals; (10) 176–189 ventrals in males; (11) 41–44 subcaudals in males; (12) dorsum beige with black round blotches decreasing in size posteriorly; (13) venter uniformly creamish white, tail brown pigmented on the median suture of subcaudals; (14) moderate body size, with male reaching
316 mm
SVL; (15) long tail size in the male (16.8% SVL).
Comparisons:
Among all congeners,
A. boulengerii
shares only with
A. medusa
sp. nov.
(see below) 17 dorsal scale rows, five well-spaced maxillary teeth with a single postdiastemal tooth, more than 40 subcaudals in males, and dorsum with black nuchal collar and round body blotches decreasing in size posteriorly.
Atractus boulengerii
differs from
A. medusa
in having 176–189 ventrals in males, first three infralabials contacting chinshields, four gular scale rows, and four preventrals (vs. 133 ventrals in the single male, first four infralabials contacting chinshields, three gular scale rows, and two preventrals).
Description
: Head twice as long as wide, arched in lateral view, rounded in dorsal view; snout truncate in lateral view, rounded in dorsal view; cervical constriction barely defined; rostral sub-triangular in frontal view, broader than high, poorly visible in dorsal view; internasal longer than wide; internasal suture sinistral with respect to prefrontal suture; prefrontal as long as wide; supraocular sub-trapezoidal, twice as long as wide; frontal pentagonal, as long as wide; parietal about 1.5 times as long as wide; nasal divided; nostril located between prenasal and postnasal; prenasal twice as high as long; postnasal as high as long; loreal long, contacting second and third supralabials; pupil round; two postoculars of similar size; upper postocular slightly longer than lower postocular; temporals 1+2; first temporal twice as long as high; upper posterior temporal elongate, four times as long as wide; seven supralabials, third and fourth contacting orbit; first three supralabials of similar size and lower than fourth; fifth supralabial higher than first four and lower than sixth supralabial; sixth supralabial higher and seventh longer than remaining supralabials; symphisial subtriangular, twice as broad as long; six infralabials, first three contacting chinshields; first pair of infralabials in contact behind symphisial, preventing symphisial/chinshields contact; four gular scale rows; four preventrals; 17/17/17 smooth dorsals; dorsals lacking apical pits, supra-anal tubercles, and keels; terminal spine moderate, conical, and acuminate.
Maxillary arch:
Arched in dorsal view, with four prediastemal and one postdiastemal teeth; prediastemal teeth large, well spaced, curved posteriorly, angular in cross section, robust at base, narrower at apices, decreasing abruptly in size; maxillary diastema short; postdiastemal tooth slightly smaller than last prediastemal tooth.
Colour in preservative:
(based on
holotype
original description and specimen UV-C 6591) Dorsum of head with black cephalic cap extending from rostral to anterior third of parietals; wide occipital band creamish yellow, situated between anterior region of parietals and second dorsal scale rows; background of head black to dorsal margin of supralabials ventrally and to the level of postoculars posteriorly; temporal and occipital regions creamish yellow; supralabials, infralabials, chinshields, and gular region cream; venter uniformly cream; tail cream with small dark brown dots concentrated along the median sutures of subcaudals, forming an irregular line; dorsal ground colour of body beige with about 60 round black blotches paired above paravertebral region; body anteriorly with a wide black collar (six scales long) and large transversal blotches (four or five scales wide); transverse blotches paired or alternating on the flanks, decreasing gradually in size; blotches reaching second dorsal scale rows anteriorly and restricted to paravertebral region posteriorly; vertebral line (one scale wide) distinct on the anterior and posterior thirds of body and tail; vertebral line connected to dorsal blotches; tail dorsally with pattern similar to body.
Variation:
Additional male specimen have
310 mm
SVL,
52 mm
CL; tail 16.8% of SVL; 176 ventrals; 141 subcaudals; four gular scale rows; four preventrals; eight or nine dorsal scales on the level of second subcaudal; body diameter
5.2 mm
.
Distribution:
Rediscovered at the lower Anchicayá River, on the old road between Cali and Buenaventura (
03º44’N
,
76º58’W
, ca.
100 m
), department of Valle del Cauca, Pacific lowlands of
Colombia
.
Atractus boulengerii
apparently inhabits rainforest near sea level (
Fig. 2
).
FIGURE 2.
Geographic distribution of the
Atractus multicinctus
species group.
Remarks:
Peracca (1896)
described
Atractus boulengerii
and
A. iridescens
on the basis of two specimens from “
America
Meridionali”, without precise collection data.
Boulenger (1913)
associated three individuals from Peña Lisa and Condoto in the department of Chocó in
Colombia
with
A. iridescens
(see remarks of
A. iridescens
), but
A. boulengerii
remained known only from the
holotype
. In the course of this revision of the Pacific
Atractus
, we found a specimen (UV-C 6591, adult male), from the municipality of Buenaventura, department of Valle del Cauca,
Colombia
, which matches the original species description, except for having 176 ventrals and 41 subcaudals (vs.189 ventrals and 44 subcaudals in the
holotype
of
A. boulengerii
). These small count differences are entirely acceptable in accordance with the pattern of variation of ventral and subcaudals reported for the genus (Savage 1960; Passos 2008), and therefore we refer herein this specimen to
A. boulengerii
.