Atractus clarki Dunn and Bailey, 1939

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 : 5-8

Atractus clarki Dunn and Bailey, 1939

Fig. 3

Atractus clarki Dunn and Bailey, 1939 , Bull. Mus. Comp. Zool. 86:8. Atractus clarki— Myers, 2003, Amer. Mus. Novit. 3391:10.

Holotype: Adult female, Museum of Comparative Zoology, Harvard University, MCZ 28800, from a mine at Santa Cruz de Cana (± 07º46’N, 77º41ºW, ca. 500 m), province of Darién, Panamá, collected on 1938 by a native worker (photographs examined).

Diagnosis: Atractus clarki is distinguished from all congeners by the combination of the following characters: (1) 17/17/17 smooth dorsals; (2) generally two postoculars; (3) loreal long; (4) temporals 1+2; (5) seven supralabials, third and fourth contacting orbit; (6) six or seven infralabials, generally first three contacting chinshields; (7) six or seven maxillary teeth; (8) generally four gular scale rows; (9) three or four preventrals; (10) 169–195 ventrals in females, 153–165 in males; (11) 32–33 subcaudals in females, 34–40 in males; (12) dorsum black with tiny transversal bands in flanks, occasionally contacting the opposite one on the vertebral region; (13) venter cream with dark lateral margins and posterior region of ventrals with dark brown diffuse dots; (14) moderate body size, females reaching 354 mm SVL, males 300 mm SVL; (15) moderate tail size in females (11.3–13.6% SVL), moderately to long (13.2–18.3% SVL) in males; (16) hemipenis strongly bilobed, semicapitate, semicalyculate.

Comparisons: Among all congeners, A. clarki shares only with A. boulengerii and A. multicinctus 17 dorsal scale rows, more than 35 subcaudals in males, generally six infralabials, five to seven well spaced maxillary teeth, colour pattern with transversal blotches or bands, complete occipital cream band, occipital band wide laterally and constricted dorsally, venter almost interely cream (if spotted, only on posterior third of body), body diameter less than 5 mm. Atractus clarki differs from A. boulengerii and A. multicinctus by having 153–165 ventrals in males and dorsum black with tiny cream bands (vs. ventrals 176–189 in males of A. boulengerii and 168–183 in males of A. multicinctus ; dorsum beige with dark blotches [ A. boulengerii ] or bands [ A. multicinctus ] alternating above the flanks).

Description: Head twice as long as wide, arched in lateral view, rounded in dorsal view; snout truncate in lateral view, slightly rounded in dorsal view; cervical constriction indistinct; 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 twice as long as wide; nasal divided; nostril restricted to prenasal; prenasal about twice as high as long; postnasal as high as long; loreal long, contacting second and third supralabials; pupil round; generally two postoculars of similar height; upper postocular slightly longer than lower postocular; temporals 1+2; first temporal twice as long as high; upper posterior temporals elongate, four or five times as long as wide; seven supralabials, third and fourth contacting orbit; second and third supralabials higher than fourth; sixth supralabial higher and seventh longer than remaining supralabials; symphisial triangular, twice as broad as long; six or seven infralabials, generally first three contacting chinshields; first pair of infralabials in contact behind symphisial, preventing symphisial/chinshields contact; chinshields about three times as long as wide; generally four gular scale rows; three or four preventrals; 17/17/ 17 smooth dorsal scale rows; dorsals lacking apical pits, supra-anal tubercles, and keels; caudal spine short, robust, and rhomboidal.

Maxillary arch: Arched in dorsal view, with four or five prediastemal and one or two postdiastemal teeth; first three prediastemal teeth large and moderately spaced; third and fourth teeth well spaced; fourth and fifth teeth smaller and more curved than anterior ones; prediastemal teeth angular in cross section, robust at base, narrower at apices; maxillary diastema moderately long; postdiastemal teeth slightly smaller than last prediastemal tooth; lateral process poorly developed, lacking posterior projection.

Colour in preservative: Dorsum of head with black cephalic cap extending from rostral to anterior third of parietals; cream occipital band covering median to posterior portion of parietals, temporals, and occipital region; background of head black to dorsal margin of supralabials; ventral and posterior limits of black cap reaching dorsal margins of supralabials and postoculars, respectively; supralabials cream; mental region generally immaculate cream; occasionally infralabials and anterior portion of chinshields dark; preventrals cream; venter anteriorly cream, with black pigment reaching lateral edges of ventrals; posterior portion of venter frequently with scattered small dark brown dots distributed irregularly; tail generally cream with lateral margins black; tail occasionally cream with small black dots concentrated on median suture of subcaudals; tail rarely black with cream spots in centre of each subcaudal; dorsal ground colour black with about 30 tiny transverse light bands (one scale long) reaching paraventral region; transverse bands cream, occasionally connected to opposite side across vertebral region.

Hemipenis morphology (everted organ n = 1): Retracted organ bifurcates at eighth and extends to the level of 11th subcaudal. Hemipenis strongly bilobed, semicapitate, and semicalyculate; lobes clearly distinct from capitulum and of similar size to hemipenial body; lobes subcylindrical, centrifugally oriented, flattened on apices; lobes and capitulum covered with concentrate papillate calyces; capitular groove indistinct on sulcate and well marked on asulcate side of hemipenis; capitulum located just above bifurcation of sulcus spermaticus, longer than hemipenial body, and similar in size to lobes; intrasulcar region of capitulum with three large, narrow, hooked spines; non-lobular portion of capitulum with spinulate calyces and moderate alary spines; sulcus spermaticus bifurcates on basal portion of hemipenial body; branches of sulcus spermaticus centrifugally oriented, running to tips of lobes; sulcus spermaticus margins stout, moderately expanded, bordered with spinules at basal portion of organ and papillae on the lobular region; hemipenial body subelliptical, broader than capitulum, uniformly covered with moderate hooked spines; large spines concentrated on basal portion of hemipenial body; basal naked pocket extending to basal third of hemipenial body; basal portion of hemipenis with longitudinal plicae and disperse spinules ( Fig. 4 a).

Variation: Largest male 300 mm SVL, 51 mm CL, largest female 354 mm SVL, 42 mm CL; tail 13.2– 18.3% (x¯ = 15.6; SD= 2.6; n = 4) SVL in males, 11.3–13.6% (x¯ = 12.8; SD = 1.0; n = 4) SVL in females; 153– 165 (x¯ = 164.2; SD = 11.6; n = 4) ventrals in males, 169–195 (x¯ = 181.7; SD = 13.0; n = 3) in females; 34–40 (x¯ = 37.7; SD = 2.9; n = 4) subcaudals in males, 31–36 (x¯ = 32; SD = 1; n = 3) in females; 6 (n = 16 sides) or 7 (n = 6 sides) infralabials; 1 (n = 1 side) or 2 (n = 21 sides) postoculars; 3 (n = 20 sides) or 4 (n = 2 sides) infralabials contacting chinshields; 3 (n = 1 side) or 4 (n = 8 sides) gular scale rows; 3 (n = 3) or 4 (n = 3) preventrals; 8–10 (x¯ = 8.5; SD = 0.6; n = 10 sides) dorsal scale rows at the level of second subcaudal; 3.1–5.4 mm (x¯ = 4.0; SD = 0.6; n = 5) body diameter; 5 (n = 2 sides), 6 (n = 2 sides) or 7 (n = 4 sides) maxillary teeth; retracted hemipenis bifurcates between sixth to ninth and extends between eighth to 11th subcaudal (n =2).

Distribution: Pacific region of Panama and Colombia from Santa Cruz de Cana (07º46’N, 77º41W) in the province of Darién, Panama south to Istima (05º09’N, 76º41’W) in the department of Chocó, Colombia, and on both sides of the Cordillera Occidental of the Colombian Andes from Anori (07º11’N, 75º04’W) in the department of Antioquia, south to Restrepo (03º49’N, 76º31’W) in the department of Valle del Cauca. Atractus clarki inhabits rainforest and riparian forests of the Rivers derived from Cordillera Occidental, at elevations of 100–1500 m ( Fig. 2 ).

Remarks: Dunn and Bailey (1939) described A. clarki based on a single specimen. Myers (2003) redescribed the holotype and reported the second known specimen on the basis of an individual collected at Colombian Chocó but lacking specific collection data. We report herein meristic, morphometric, colour, and hemipenial variation based on eight additional specimens from this poorly known species.

Figures

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

FIGURE 3. Dorsal (A) and ventral (B) views of Atractus clarki (MHUA 14000). SVL 327 mm, CL 37 mm.

FIGURE 4. Sulcate and asulcate sides of the hemipenis of (A) Atractus clarki (ICN 10826) and (B) Atractus multicinctus (ICN 7075). Scale = 5 mm.