Atractus alytogrammus Köhler & Kieckbusch, 2014, sp. nov.

Atractus alytogrammus sp. nov.

Figs. 1–3

Holotype. A male, SMF 88371, collected on January 9 1957 by Federico Medem in the Serrania de la Lindosa (2.46782°, -72.73155°), south of the municipality of San José del Guaviare, department of Guaviare, Colombia.

Diagnosis. A species of the genus Atractus that differs from all congeners by the following combination of characters: (1) 17 smooth dorsal scale rows; (2) preocular absent; (3) loreal present, approximately as long as high; (4) temporals 1+2; (5) seven supralabials; (6) seven infralabials; (7) five maxillary teeth; (8) four gular scale rows; (9) four pre-ventrals; (10) 187 ventrals in single male; (11) 29/31 subcaudals in single male; (12) dorsum of body with longitudinal stripes; (13) venter uniformly dark gray; (14) SVL of single male 297 mm; (15) small to moderate tail length in single male (11.8 % of SVL); (16) hemipenis morphology unknown.

Comparisons. Among all currently recognized congeners, Atractus alytogrammus shares a dark venter and is morphologically similar to A. steyermarki, A. nigriventris, and A. trivittatus. It differs from A. steyermarki by having a uniform dark gray venter (vs. venter pale with a midventral stripe in A. steyermarki), 187 ventrals (vs. 160–167 in males in A. steyermarki), and 29/31 subcaudals (vs. 37–44 in males in A. steyermarki). Atractus alytogrammus differs from A. nigriventris and A. trivitattus by having a dorsal body pattern of longitudinal lines (vs. dorsum brown with black blotches in A. nigriventris and A. trivitattus) and 187 ventral scales in single known male (vs. 175 in single known female of A. nigriventris, 176 in single known female of A. trivitattus). Atractus alytogrammus differs further from A. trivitattus by having seven supralabials (vs. eight in A. trivitattus). Among congeners from Colombian Amazonia and surrounding lowlands, A. alytogrammus shares only with A. univittatus (Jan 1862) the combination of having 17 dorsal scale rows, seven supralabials, and a pattern with longitudinal stripes or lines on dorsum. Atractus alytogrammus differs from A. univittatus by having 187 ventrals in the single male (vs. 151–160 ventrals in males of A. univittatus), seven infralabials (vs. six infralabials in A. univittatus), and a uniform dark venter with lighter speckles on the edges (vs. a yellowish white venter in A. univittatus).

Description of the holotype. Male; SVL 297 mm; moderate TL 35 mm (complete; 11.8 % SVL); TTL 332 mm; head not distinct from body; body cylindrical, diameter at midbody 5.2 mm (1.8 % of SVL); head rounded in dorsal view; HL 9.41 mm (3.2 % SVL); HW 4.9 mm (65.3 % of HL); snout rounded in dorsal view, rounded in lateral view; eye diameter 1.03 mm; pupil round; interorbital distance 3.2 mm (42.7 % HL); rostro-orbital distance 2.9 mm (38.7 % HL); naso-orbital distance 1.4 mm (18.7 % HL). 17/17/17 smooth dorsal scale rows, 16 dorsal scale rows above cloaca, 9 dorsal scale rows above second subcaudal; apical pits absent; 187 ventrals; 29/31 divided subcaudals; some of the subcaudals fused; 4 preventrals; cloacal scute entire; rostral well visible from above, subtriangular, wider than high (rostral height 1.3 mm, rostral width 2.24 mm); two subpentagonal internasals, height 0.7 mm, width 1.04 mm; internasal suture sinistral in respect to prefrontal suture; nostril in suture of prenasal and postnasal; 1/1 hexagonal postnasal, length 0.7 mm, height 0.7 mm; short subrectangular loreal, approximately as high as long (loreal length 0.7 mm; loreal height 0.6 mm; ratio length/height: 1.17); preocular lacking; two subrectangular postoculars, upper postocular larger than lower (upper postocular length 0.4 mm; upper postocular height 0.4 mm); temporal formula 1+2, anterior temporal larger than posterior temporals, posterior temporals equal in size (anterior temporal: height 0.9 mm, length 1.7 mm; upper posterior temporal: height 0.7 mm, length 1.0 mm); seven supralabials, first four equal in size; fifth, sixth seventh supralabials larger, sixth the largest; second and third supralabial in contact with loreal; third and fourth supralabial in contact with the eye; seven infralabials, first three infralabials in contact with the chin shields; first pair of infralabials smaller than rest; first pair of infralabials in contact, preventing contact of mental and chin shields; gular scale rows from infralabials to preventrals four; two chin shields, length 2.5 mm, width 0.7 mm; two subpentagonal prefrontals, length 1.5 mm, width 1.6 mm; pentagonal supraoculars, length 1.1 mm, width 0.6 mm; subtriangular frontal, frontal apex slightly protruding, length 2.1 mm, width 2.0 mm; parietal length 3.7 mm, width 2.0 mm.

Coloration of the holotype. After 56 years preservation in 70% ethanol: dorsal and lateral surfaces of head Hair Brown (277); most supralabials with Smoke Gray (266) speckles; surface of the chin region Fawn Color (258); ground color of the ventrals and subcaudals Dusty Brown (285) with Pale Buff (1) speckles on the edges of ventrals; dorsal ground color Sepia (279) with Verona Brown (37) mottling on the edges of the dorsal scales; a Drab (19) dashed line on the first dorsal scale row present from below level of a point four scales behind posterior tip of parietals to level of cloaca; a Drab (19) dashed line on the second dorsal scale row present from below level of a point four scales behind posterior tip of parietals to about one fourth of body where it becomes indistinct and disappears; a Fawn Color (258) longitudinal, continuous line on the fifth dorsal scale row present, from a point four scales behind posterior tip of parietals to tip of tail; a Dusty Brown (285) vertebral stripe present from posterior tip of parietals to tip of tail.

Etymology. The name alytogrammus is a compound noun derived from alytos (Greek for “unbroken”) and gramme (Greek for “line”) referring to the continuous dorsolateral pale stripe in this species.