Atractus boulengerii Peracca, 1896

Passos, Paulo, Mueses-Cisneros, Jonh Jairo, Lynch, John D. & Fernandes, Ronaldo, 2009, Pacific lowland snakes of the genus Atractus (Serpentes: Dipsadidae), with description of three new species, Zootaxa 2293, pp. 1-34 : 3-5

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).

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 ).

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 .

Figures

FIGURE 1. Dorsal (A) and ventral (B) views of Atractus boulengerii (UV-C 6591). SVL 310 mm, CL 52 mm.

FIGURE 2. Geographic distribution of the Atractus multicinctus species group.