Atractus torquatus ( Duméril, Bibron & Duméril, 1854 ), Dumeril, Bibron & Dumeril, 1854

Passos, Paulo & Prudente, Ana L. C., 2012, Morphological variation, polymorphism, and Taxonomy of the Atractus torquatus complex (Serpentes: Dipsadidae), Zootaxa 3407, pp. 1-21 : 4-17

publication ID	https://doi.org/ 10.5281/zenodo.214128
DOI	https://doi.org/10.5281/zenodo.5679973
persistent identifier	https://treatment.plazi.org/id/03B43F6C-FFA2-FF89-98F5-F8B3958BF94E
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scientific name	Atractus torquatus ( Duméril, Bibron & Duméril, 1854 )
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Atractus torquatus ( Duméril, Bibron & Duméril, 1854)

Figs. 1–7 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 , 11–12 View FIGURE 11 View FIGURE 12 .

Brachyorrhos torquatum F. Boie, 1827 ; Isis Von Oken:540. (nomen nudum).

Calamaria badia — Schlegel, 1837; Essai sur la Physignomie des Serpens:35. (part.) Rabdosoma torquatum Duméril, Bibron & Duméril, 1854 ; Erpétologie Générale:101.

Rabdosoma varium Jan, 1862 ; Arch. Zool. Anat. Fis. 2:18.

Atractus torquatus – Boulenger, 1894; Catalogue of the Snakes in the British Museum 2:309.

Atractus sp. A – Dixon & Soini, 1977; Contr. Biol. Geol. Milwalke Publ. Mus. 12:37.

Atractus torquatus – Dixon & Soini, 1986; The Reptiles of Upper Amazon Basin, Iquitos, Peru. 2nd ed. Milwaukee, Wisconsin Milwaukee Public Museum 154:96.

Atractus davidhardi Silva, 2004 ; Rev. Acad. Col. Cien. Exat. Fis. Nat. 108:418. New synonymy.

Atractus janethae Siva, 2004 ; Rev. Acad. Col. Cien. Exat. Fis. Nat. 108:429. New synonymy.

Atractus lucilae Silva, 2004 ; Rev. Acad. Col. Cien. Exat. Fis. Nat. 108:434. New synonymy.

Lectotype: Adult male, RMNH 114, collected by H. Dieperink in Guyana. Hoogmoed (1980) designated the lectotype and restricted the type locality to Paramaribo (05º50’N, 55º10’W, sea level) in Suriname (specimen photograph examined; Fig. 12 View FIGURE 12 ). It specimen is also the holotype of Rabdosoma varium ( Fig. 11 View FIGURE 11 ).

Paralectotypes: RMNH 115, adult female, same data as lectotype; RMNH 117a,b,c,d,e, originally from “Gabinet Hendrix” lacking additional data, these specimens were later donated to RMNH ( Hoogmoed 1980); Muséum national d’Histore naturelle (MNHN 0.437), from Santa Cruz de La Sierra (17º48’S, 63º10’W; ca. 440 m), department of Santa Cruz, Bolivia.

Diagnosis. Atractus torquatus can be distinguished from all congeners by the combination of the following characters: (1) 17 smooth dorsal scale rows; (2) usually a single postocular; (3) long loreal; (4) temporals 1+2; (5) usually eight supralabials, third and fourth or fourth and fifth contacting orbit; (6) usually eight infralabials, first four contacting chinshields; (7) six to nine maxillary teeth; (8) three or four gular scale rows; (9) three or four preventrals; (10) 151–172 ventrals in females, 144–166 in males; (11) 34–47 subcaudals in females, 35–53 in males; (12) dorsum in preservative dull red to reddish brown, uniform coloured or presenting since paravertebral black dots until transversal alternated blotches reaching paraventral region; (13) venter in preservative uniformly cream or presenting disperse dark brown dots along the body; (14) large body size, females reaching 683 mm SVL, males 525 mm SVL; (15) moderate to long tail length in females (12.4–18.7% SVL), long tail length (15.6–20.9% SVL) in males; (16) hemipenis moderately bilobed, semicapitate and semicalyculate.

Comparisons. Among all congeners, Atractus torquatus shared 17 dorsal scale rows at midbody, large maximum body size (> 500 mm in both sexes), long tail (generally> 15% SVL in both sexes) and dorsal ground colour red to reddish brown covered by black bands only with A. badius . Atractus torquatus differs from A. badius by having usually a single postocular, generally infralabial, first four infralabials contacting chinshields, and blotches or bands never forming diads (vs. two postoculars, seven infralabials, first three infralabials contacting chinshields and dorsal bands forming conspicuous diads on anterior portion of body).

Description. Head twice as long as wide, slightly arched in lateral view, sub-triangular in dorsal view; snout slightly acuminate in lateral view, round in dorsal view; conspicuous canthus rostralis in lateral view; cervical constriction indistinct; rostral about twice as wide as high, subtriangular in frontal view, poorly visible in dorsal; internasal as wide as long; internasal suture sinistral with respect to prefrontal suture; prefrontal longer than wide; supraocular sub-trapezoidal, about twice as long as wide; frontal pentagonal, longer than wide; parietal about twice as long as wide; nasal divided; nostril located between prenasal and postnasal; prenasal twice as high as long; postnasal as high as long; loreal moderately long, contacting second, third and fourth supralabials; pupil subelliptical or rounded; usually a single postocular as high as long; eventually two postocular, similar in size; temporals 1+2; first temporal about 60–70% times longer than high; upper posterior temporals usually non fused; usually eight supralabials, fourth and fifth contacting orbit; first two or three supralabials with similar high and smaller than fourth supralabial; sixth or seventh supralabials higher and seventh or eighth longer than remaining supralabials; symphysial sub-triangular, two or three times as wide as long; first pair of infralabials contacting behind symphysial, perventing symphysial/chinchields contact; usually eight infralabials, first four contacting chinshields; chinshields about three times as long as wide; three or four gular scale rows; three or four preventrals; 17 smooth dorsal scale rows on midbody, lacking apical pits, supra-anal tubercles, and keels; caudal spine moderately long, conical, and acuminate.

Maxillary arch. Arched in dorsal view, with five to seven prediastemal and one to three postdiastemal teeth; prediastemal teeth with similar size, large, moderately spaced, curved, angular in cross section, robust at base, and narrower on the apices; maxillary diastema short; postdiastemal teeth smaller than last prediastemal one; lateral process of maxilla poorly developed, lacking posterior projection.

Colour pattern in preservative. Dorsum of head pale brown to dark brown, reaching posterior region of parietals; frequently anterior region of snout darker than posterior cephalic scales and body; background of head reddish to dark brown, region around orbit eventually black; supralabials most cream with dorsal edge dark brown; ventral margins of supralabials usually cream; last two supralabials eventually covered with brown pigment; mental region cream with dark brown dots or blotches covering symphysial, first pair of infralabials, and anterior portion of chinshields; mental region of second to fourth pair of infralabials eventually covered by dark brown blotches; preventrals uniformly cream; belly uniformly cream or pale brown, frequently covered by small disperse dark brown dots; belly eventually heavy pigmented by irregular dark brown dots or well defined squared or rhomboid blotches; underside of tail usually cream with irregular dark brown dots; sometimes tail most brown with lighter centre; rarely tail uniform cream; dorsal ground colour of body red to reddish brown, with black collar on neck (one to four scales long); black collar located on second to fourth dorsal rows; eventually the medial portion of collar discontinuous or absent; dorsum of body usually with disperse paravertebral black spots (one or least of one scale long), alternate transversal flecks (one or two scales long) or bands (two or three scales long), covering paravertebral region and sometimes reaching lateral portion of flanks; dorsum with large anterior transversal flecks or bands generally connecting disperse paraventral spots; eventually dorsal flecks or bands decreasing in size posteriorly, becoming disperse spots or small blotches restricted to paravertebral region; transversal flecks or bands eventually keep it size of anterior ones along the body (three or four scales long); banded pattern with 25–50 alternated blotches, connecting the opposite one above vertebral region; bands usually twice as long as interspaces; eventually alternate bands connected above vertebral region constituting a zig-zag pattern, more conspicuous on posterior third of body. Melanism tendency rarely noted in individuals, with dorsum of head black and dorsal ground colour pale brown to brown covered by alternate black bands ( Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 , 6–7 View FIGURE 6 View FIGURE 7 , 11–12 View FIGURE 11 View FIGURE 12 ). The melanic individuals occur in low frequency along the species distribution and did not show any geographic structure.

Colour in life. Dorsum and background of head uniformly red to reddish brown; dorsal ground colour of body dull red to reddish brown with black dots, flecks, or bands; ventral portion of supralabials, mental region, and belly cream to creamish yellow; belly frequently covered by dark brown dots or blotches; underside of tail cream to creamish yellow, with dark brown to black dots; eye brown to red ( Fig. 5 View FIGURE 5 ).

Hemipenis morphology. Inverted organ bifurcates in the level of seventh and extends to ninth subcaudal. Hemipenis slightly to moderate bilobed, semicapitate, and semicalyculate; lobes sub-cylindrical with rounded apices, similar size and oriented centripically; capitular crotch evident but incomplete on asulcate (median portion covered by moderated spines) and sulcate (region adjacent to bifurcation of sulcus spermaticus branches); capitulum define basal region of lobes on both sides of organ; lobes covered by spinulate calyces in it basal portion and papillate calyces at apical region; tip of lobes usually nude and sometimes scattered by papillate calyces; sulcus spermaticus divides on distal portion of hemipenial body below to capitular crotch; intrasulcar region with moderate hooked spines; sulcus spermaticus branches centrifugally oriented running to tip of lobes; margins of sulcus spermaticus stout and bordered by spinules on basal to most of distal portion of lobes; sulcus spermaticus expanded at apices of lobes; hemipenial body subelliptical, narrower than lobular region of organ; hemipenial body covered by spines on both sides of organ; distal region of hemipenial body barely defined by transversal series of largest spines connected at the base; transversal series of spines delimited basal region of hemipenial body; proximal region of hemipenis scattered with small disperse spines; lateral portion of hemipenial body covered with naked pocket ( Fig. 9 View FIGURE 9 ).

Meristic and morphometric variation. Large male SVL 525 mm, CL 94 mm; large female SVL 683 mm, CL 96 mm; midbody diameter 1.4–4.8% (x¯ = 2.5; SD = 0.6; n = 31) SVL in males, 1.9–4.6% (x¯ = 2.7; SD = 0.5; n = 29) SVL in females; tail 15.6–20.9% (x¯ = 18.2; SD = 1.2; n = 32) SVL in males, 12.4–18.7% (x¯ = 15; SD = 1.2; n = 33) SVL in females; 144–166 (x¯ = 154.7; SD = 4.7; n = 35) ventrals in males, 151–172 (x¯ = 161.4; SD = 5.5; n = 36) in females; 35–53 (x¯ = 45.9; SD = 4.1; n = 33) subcaudals in males, 34–47 (x¯ = 40.2; SD = 3.5; n = 34) in females; 3–4 (x¯ = 3.7; SD = 0.5; n = 74) preventrals; 3–4 (x¯ = 3.7; SD = 0.4; n = 72) gular scale rows; 7 (n = 22 sides) or 8 (n = 124 sides) supralabials; 7 (n = 18 sides) or 8 (n = 128 sides) infralabials; 3 (n = 18 sides) or 4 (n = 130 sides) first infralabials contacting chinshields; 1 (n = 135 sides) or 2 (n = 11 sides) postoculars; 15/17/15 (n = 1), 15/17/17 (n =1) 16/17/16 (n = 1) or 17/17/17 (n = 25) dorsal scale rows; 7–10 (x¯ = 8.5; SD = 0.6; n = 50 sides) dorsal scale rows in the level of second subcaudal; 3.8–18.6 mm (x¯ = 9.5; SD = 3.8; n = 63) midbody diameter; 6 (n = 3 sides), 7 (n = 23 sides), 8 (n = 100 sides) or 9 (n = 11 sides) maxillary teeth; anal gland extends from third to fourth subcaudal (n = 4).

Distribution. The distribution of Atractus torquatus is known to include the Guiana Shield and Amazon Basin (without known records in the eastern portion of the Amazonia), occurring from Paramaribo (5º50’N, 55º10’W) in Suriname southwestern to Iquitos (3º44’53’’S, 73º14’50’’W) in Peru. We place in doubt the record of Atractus torquatus from Santa Cruz de La Sierra in Bolivia, since there is no additional report of the species based on voucher specimen below department of Loreto in north of the Peruvian Amazonia ( Hoogmoed 1980; Passos 2008). Atractus torquatus inhabits lowlands portions of Neotropical Savanah and Amazon Rainforest from 0–500 m altitude ( Fig. 13 View FIGURE 13 ).

Remarks. The diagnoses provided by Silva (2004), possibly with the exception of Atractus davidhardi in which he also included some hemipenial features, were inadequate to distinguish these forms from any other congener. Moreover, many of the characters used by the author were in error (see Tab. 1 View TABLE 1 ). Therefore, all putative diagnostic features of the Amazon basin taxa proposed by Silva falls within know morphological variation of the Atractus torquatus .

Characters ICN 10096 ICN 10104 ICN 10105