Atractus typhon, Passos, Paulo, Mueses-Cisneros, Jonh Jairo, Lynch, John D. & Fernandes, Ronaldo, 2009

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 : 26-29

Atractus typhon sp. nov.

Figs. 17 , 18

Holotype: Adult male, ICN 10901, from Reserva Natural Biotopo Selva Húmeda (01º25’N, 78º17’W, ca. 600 m), vereda Berlín, El Diviso, municipality of Barbacoas, department of Nariño, Colombia, collected by B. Cépeda and J. J. Mueses-Cisneros on 14 July 2006.

Diagnosis: Atractus typhon is distinguished from all congeners by the following combination of characters: (1) 15/15/15 smooth dorsal; (2) two postoculars; (3) long loreal; (4) temporals 1+2; (5) seven supralabials, third and fourth contacting orbit; (6) seven infralabials, first three contacting chinshields; (7) seven maxillary teeth; (8) three gular scale rows; (9) three preventrals; (10) 156 ventrals in the single male; (11) 58 subcaudals in male; (12) dorsal ground colour beige with broad black bands alternated in the flanks; (13) venter cream with dark brown squared blotches concentrated on lateral portion of ventrals; (14) moderate body size, with males reaching 293 mm SVL; (15) long tail (27.0% SVL); (16) hemipenis moderately bilobed, semicapitate, semicalyculate.

Comparisons: Atractus typhon is distinguished from all congeners, except A. iridescens , by having a large lateral projection in the basal portion of hemipenis. Atractus typhon differs from A. iridescens by having 15/15/15 dorsals and 58 subcaudals in males (vs. 17/17/17 dorsals and 36–38 subcaudals in males).

Description of holotype: Adult male, SVL 293 mm, CL 79 mm (27% SVL); head length 13.0 mm (4.4% SVL); head width 6.2 mm (48% of head length); body diameter 7.3 mm (2.6% of SVL); interocular distance 3.9 mm; rostro-orbital distance 3.9 mm; naso-rostral distance 3.0 mm; head flattened in lateral view, subtriangular in dorsal view; snout truncate in lateral view, rounded in dorsal view; cervical constriction indistinct; rostral subtriangular in frontal view, 1.5 mm wide, 1.2 mm high, poorly visible in dorsal view; internasal 0.9 mm long, 0.9 mm wide; internasal suture sinistral with respect to prefrontal suture; prefrontal 2.5 mm long, 2.3 mm wide; supraocular subtriangular, 1.9 mm long, 1.0 mm wide; frontal subtriangular, 3.1 mm long, 2.7 mm wide; parietal 5.1 mm long, 2.8 mm wide; nasal divided; nostril almost restricted to prenasal; prenasal 0.6 mm high, 0.3 mm long; postnasal 0.4 mm high, 0.5 mm long; loreal 2.4 mm long, 0.3 mm high, contacting second and third supralabials; eye diameter 1.6 mm; pupil round; two postoculars of similar size; upper postocular 0.4 mm high, 0.4 mm long; temporals 1+2; first temporal 1.6 mm long, 0.9 mm high; upper posterior temporal elongate, 4.2 mm long, 1.0 mm wide; seven supralabials, third and fourth contacting orbit; second supralabial higher than first and with similar size of third; sixth (left side) and seventh (right side) higher and longer than remaining supralabials; symphisial subtriangular, 1.7 mm wide, 0.5 mm long; seven infralabials, first three contacting chinshields; first pair of infralabials in contact behind symphisial, preventing symphisial/chinshields contact; chinshields 2.9 mm long, 0.9 mm wide; three gular scale rows; three preventrals; 156 ventrals; 58 subcaudals; 15/15/15 smooth dorsal scale rows; dorsals lacking apical pits, supra-anal tubercles, and keels; six dorsal scale rows at the level of second subcaudal; caudal spine long, conical, narrow, and acuminate.

Maxillary arch: Arched in dorsal view, with six prediastemal and one postdiastemal teeth; prediastemal teeth large, of similar size, curved posteriorly, angular in cross section, robust at base, and narrower at apices; first four teeth poorly spaced, space between 4–5th and 5–6th teeth moderately long; maxillary diastema long; postdiastemal teeth half size of the last prediastemal tooth; lateral process moderately developed, lacking posterior projection.

Colour in preservative of holotype: Dorsum of head uniformly black; background of head uniformly black to ventral margin of supralabials; supralabials black, except for cream area on the anterior portions of each scale; mental region mostly black with light spots covering anterior region of each scale; fifth infralabial mostly cream; belly anteriorly cream with squarish black blotches concentrated on lateral portion of ventrals; ventral blotches lacking median connection at midbody; posterior third of belly with ground colour creamish gray; ventral blotches more concentrated posteriorly, forming a barely variegated pattern; lower surface of tail black, with diffuse cream spots; dorsal ground colour reddish light brown with 39–40 alternating black bands (three to five scales long), decreasing in size posteriorly; opposite bands connected along vertebral line, and reaching paraventral region along all of body; 43 reddish brown interspaces (one to three scales long), increasing in size from about midbody; paraventral region cream between dorsal bands; tail dorsally most black, with light interspaces weakly defined.

Hemipenis morphology (everted organ n = 2): Hemipenis moderately bilobed, semicapitate, and semicalyculate; lobes distinct of and restricted to distal region of capitulum; lobes attenuated and barely centrifugally oriented; lobes and capitulum uniformly covered with small spinulate calyces; calyces transversally arranged, forming conspicuous calyculate flounce above lobular region; capitular groove indistinct on the sulcate and weakly distinct on the asulcate side of organ; barely defined capitulum situated just above sulcus spermaticus bifurcation; capitulum slightly higher on the sulcate and smaller on the asulcate side than hemipenial body; sulcus spermaticus bifurcates at middle of organ; sulcus spermaticus branches centrifugally oriented, running to the tips of lobes; margins of sulcus spermaticus stout and narrow, bordered with spinules along sulcus’ extension; hemipenial body subelliptical, broader than capitulum, covered with moderate hooked spines; large spines located at lateral portion of sulcate side of the hemipenis; basal naked pocket extends to distal portion of hemipenial body; proximal region of hemipenis with longitudinal plicae and a large lateral projection ( Fig. 9 b).

Etymology: The specific epithet “ typhon ” is derived from the name of the Greek monster Typhon (Greek: Τυφoν). According to the Greek myth, Typhon married Echydna and fathered most mythological monsters that populated Earth. Typhon was described by the Greek writer Hesiod as one of the most fearsome of all creatures, “covered by a hundred serpent heads with dark flickering tongues flashing fire from their eyes”. This word is employed herein to allude to the impressive aspect of Atractus typhon .

Distribution: Known only from Barbacoas in the Pacific versant of Cordillera Occidental at the department of Nariño, Colombia. Atractus typhon inhabits rainforest at 600 m elevations ( Fig. 6 ).

Figures

FIGURE 6. Geographical distribution of the Atractus paucidens species group.

FIGURE 9. Sulcate and asulcate sides of the hemipenis of (A) Atractus iridescens (ICN 10902), (B) detailed view of lateral expansion of the hemipenis of Atractus iridesnces, (C) sulcate and asulcate sides of the hemipenis of Atractus typhon sp. nov. (ICN 10901). Scale = 5 mm.

FIGURE 17. Dorsal (A) and ventral (B) views of the holotype of Atractus typhon sp. nov. (ICN 10901). SVL 293 mm, CL 79 mm.

FIGURE 18. Dorsal (A) and lateral (B) views of head and lateral view of body (C) of the holotype of Atractus typhon sp. nov. (ICN 10901). Scale = 10 mm.