Atractus altagratiae, Passos & Fernandes, 2008

Passos, Paulo & Fernandes, Ronaldo, 2008, A new species of the colubrid snake genus Atractus (Reptilia: Serpentes) from the central Amazon of Brazil, Zootaxa 1849 (1), pp. 59-66 : 60-63

Atractus altagratiae sp. nov.

( Figures 1–4 )

Holotype: Adult male, Museu Nacional, Universidade Federal do Rio de Janeiro, MNRJ 7888 , collected 1957 by Helmut Sick at upper Cururú River (07°12’S, 58°04’W; ca. 44 m), tributary of Teles Pires River , Municipality of Itaituba, State of Pará, Brazil.

Diagnosis: The single known male of Atractus altagratiae is distinguished from all congeners by the following combination of characters: (1) 17/17/17 dorsal scale rows, smooth, without apical pits, supranal tubercles, or keels; (2) two postoculars; (3) long loreal; (4) temporals 1+2; (5) seven supralabials, third and fourth contacting orbit; (6) seven infralabials, first four in contact with chinshields; (7) seven maxillary teeth; (8) three gular scale rows; (9) three preventrals; (10) 139 ventrals; (11) 27 subcaudals; (12) dorsal colour pattern uniform reddish brown, except the first two dorsal rows creamish white; (13) venter immaculate creamish white; (14) snout-vent length of 240 mm; (15) moderate tail size (14.6% of SVL); (16) slightly bilobed, barely semicapitate, and semicalyculate hemipenis.

Differs from all congeners except A. dunni , A. lasallei , A. lhemanni , and A. resplesdens in having 17 dorsal scale rows, seven supralabials, two postoculars, and dorsal colour pattern uniform reddish brown. Atractus altagratiae differs from these species in having the first two dorsal scale rows uniform creamish white, venter immaculate creamish white, and hemipenis slightly bilobed with lateral tip projections (vs. first dorsal scale rows reddish brown, venter deeply dark pigmented, and hemipenis moderate bilobed, lacking lateral projections).

Regarding other Amazonian species of Atractus , the new species differs from Atractus albuquerquei , A. boettgeri , A. charitoae , A. emmeli , A. elaps , A. franciscopaivai , A. heliobelliomini , A. insipidus , A. occipitoalbus , A. paravertebralis , A. poeppigui , A. punctiventris , A. taeniatus , A. tamessari , and A. trilineatus in having 17 dorsal scale rows (vs. 15 dorsal scale rows); from A. alphonsehogei , A. arangoi , A. badius , A. collaris , A. davidhardi , A. emersoni , A. favae , A. gaigeae , A. flammigerus , A. janethae , A. latifrons , A. limitaneus , A. lucilae , A. major , A, natans , A. schach , A. snethlageae , A. torquatus , A. univittatus , and A. zidoki in having a uniform reddish brown dorsal colour pattern, except for first two dorsal scale rows which are creamish white (vs. dorsal colour pattern with alternating black, red or white dorsal strikes, bands, blotches, and dots or with pale occipital band and vertebral line); from A. caxiuana in lacking a pale occipital band, apical pits, and supranal tubercles; from A. natans in having an immaculate creamish white venter (vs. darkly pigmented).

Description of the holotype: Adult male, SVL 240 mm, TL 35 mm (14.6% of SVL); head length 11.5 mm (4.8% of SVL); body diameter 5.5 mm (2.3% of SVL); head width 4.8 mm (42% of head length); interorbital distance 4.0 mm; rostrorbital distance 3.3 mm (80% interorbital distance); naso-orbital distance 2.5 mm; cervical constriction barely defined; head arched in lateral view, round in dorsal view; snout truncate in lateral view, round in dorsal view; rostral subtriangular, 2.4 mm wide, 0.9 mm high, barely visible in dorsal view; internasal 1.0 mm long, 0.7 mm wide; internasal suture sinstral with respect to prefrontal suture; prefrontal 2.3 mm long, 2.0 mm wide; supraocular subrectangular in dorsal view, 1.1 mm long, 0.6 mm wide; frontal subtriangular in dorsal view, 3.0 mm long, 2.8 mm wide; parietal 4.4 mm long, about twice as long as wide; nasal divided; nostril located between prenasal and postnasal; prenasal twice as high as long; postnasal similar in height to prenasal, slightly longer than high; loreal 2.6 long, 0.4 mm high; eye diameter 1.5 mm, pupil round; two postoculars; upper postocular taller (0.6 mm) and longer (0.4 mm) than lower postocular; temporals 1+2, first temporal 1.7 mm long, three times as long as high; upper posterior temporal elongate (2.6 mm), about five times as long as wide; seven supralabials, third and fourth contacting orbit; first supralabial higher than second; sixth supralabial higher and longer than remaining supralabials; symphisial triangular 1.7 mm width, broader than long; seven infralabials, first four contacting chinshields; first pair of supralabials in contact behind symphysial, preventing contact between symphysial and chinshields; chinshields 2.4 mm length, about three times as long as wide; three gular scale rows; three preventrals; 139 ventrals; 27 subcaudals; 17/17/17 dorsal scale rows; dorsals smooth, lacking apical pits, supranal tubercles, or keels; nine dorsal scale rows at the level of second subcaudal; caudal spine moderate, conical, and acuminate; maxilla flattened in dorsal view, with five prediastemal and two postdiastemal teeth; prediastemal teeth large, robust at the base and acuminate on the apices, angular on the cross section, moderately spaced, curved posteriorly, and all of similar size; postdiastemal teeth half size of prediastemal ones; lateral process of maxilla poorly developed, lacking posterior projection.

Colour pattern in preservative: Dorsum of head uniform reddish brown; lateral surface of head reddish brown, except anterior portion of the loreal and supralabial scales mostly cream; supralabials predominantly cream, with third, fourth, and seventh scales reddish brown; infralabials, mental region, venter, and tail immaculate creamish white; dorsum of body uniform reddish brown, except that first two dorsal scale rows are creamish white.

Hemipenis: Retracted organ bifurcates and extends to the level of the eighth subcaudal; everted organ slightly bilobed, barely semicapitate, and semicalyculate; capitular groove well defined on the asulcate side and little evident on the sulcate side; capitular groove situated just above sulcus spermaticus bifurcation; lobes restricted to distal portion of the ill-defined capitulum; lobes little distinct from base, with lateral projections containing small calyces; apical projections of lobes conical and oriented laterally; projections delimited from capitulum by depression on proximal portion of lobes; intrasulcar and medial portion of the asulcate side covered by alary spines of moderate size; calyces more conspicuous at lateral projections of lobes; spinules progressively replaced by papillae distal portion of lobes, forming weakly defined spinulate or papilate flounces; capitulum longer than hemipenial body on sulcate side and equivalent to it on asulcate side; sulcus spermaticus bifurcates on the basal portion of the hemipenial body; branches with centrifugal orientation, running to end of lobes; sulcus margins smooth, narrow, and bordered by spinules from base to apices of lobes; hemipenial body uniformly covered by moderately sized hooked spines; hemipenial body narrower than capitulum; most basal portion of hemipenial body covered in longitudinal plicae and naked pocket, located laterally on the left size ( Figs. 5–6 ).

Etymology: The specific epithet “ altagratiae ” honours Altagratia Chiesse for her extensive help rendering many Atractus illustrations and supporting the senior author during his doctorate studies.

Distribution: Known only from the type locality. This region was originally broadly covered with Amazon Rainforest so that A. altagratiae might be restricted to tropical forest.

Figures

FIGURES 1–3. Dorsal (1) and lateral (2) views of head, and lateral view of midbody (3) of the holotype of Atractus altagratiae sp. nov. (MNRJ 7888). Scale = 5 mm.

FIGURE 4. Dorsal view of the holotype of Atractus altagratiae sp. nov. (MNRJ 7888). SVL 240 mm, CL 35 mm.

FIGURE 5–6. Sulcate (5) and asulcate (6) sides of the left hemipenis of Atractus alatagratiae sp. nov. (MNRJ 7888).