Dendrophidion atlantica, Freire, Eliza Maria Xavier, Caramaschi, Ulisses & Gonçalves, Ubiratan, 2010

Freire, Eliza Maria Xavier, Caramaschi, Ulisses & Gonçalves, Ubiratan, 2010, A new species of Dendrophidion (Serpentes: Colubridae) from the Atlantic Rain Forest of Northeastern Brazil, Zootaxa 2719, pp. 62-68 : 63-67

Dendrophidion atlantica sp. nov.

“Atlantic Forest Racer” ( Figures 1–3 )

Dendrophidion dendrophis — Freire 1999.

Holotype: MNRJ 17018, adult male ( Fig. 1 ), from Mata do Engenho Coimbra (08°59’S, 35°53’W; 526 m above sea level), Municipality of Ibateguara, State of Alagoas, Northeastern Brazil, collected by Ubiratan Gonçalves on 0 5 December 2006.

Paratypes: BRAZIL: ALAGOAS: Mata do Catolé (09°40’S, 35°43’W; 122 m altitude), Municipality of Maceió: CHBEZ 853, female, collected by E. M. X. Freire on 29 September 2002; CHBEZ 697, female, collected by E. M. X. Freire on 24 May 2003; CHBEZ 2201, female, MUFAL 6064, male, collected by E. M. X. Freire on 0 5 May 1995; MUFAL 6065, male, collected by E. M. X. Freire on 24 de October 1996; MNRJ 17020, male, collected by E. M. X. Freire on 0 2 November 2001. Mata da Salva (09°32’S, 35°49’W; 85 m altitude), Municipality of Rio Largo, MUFAL 327, female, collected by E. M. X. Freire on 13 September 1992; CHBEZ 2202, male, collected by E. M. X. Freire on 0 1 November 1993. Mata do Rio Messias, Municipality of Messias (09°26’S, 35°47’W; 81 m altitude), MNRJ 17021, male, collected by J. Luiz on 0 1 May 1993. Mata da Bananeira (09o14’S, 35o48’W; 500 m altitude), Municipality of Murici, MNRJ 17019, female, collected by E. M. X. Freire on 0 4 November 1994; MUFAL 2245, male, collected by E. M. X. Freire on 22 November 1995.

Diagnosis: A species belonging to the Dendrophidion dendrophis species group, based on the presence of: (1) 17 anterior dorsal scale rows; (2) all dorsal scale rows strongly keeled; (3) dorsocaudal scale row reduction from eight to six occurring posterior to the 25th subcaudal; and (4) hemipenes with enlarged basal spines. This species is distinguished from the other members of this species group ( D. dendrophis , D. nuchale , and D. vinitor ) by having the following features: (1) 154–163 ventral scales; (2) 140–160 subcaudal scales; (3) TL 62.2–74.8% SVL; (4) collar absent; (5) head uniformly brown, dorsum brown, paler on anterior third, with transverse middorsal and lateral cream markings (one half a scale long), located within a dark brown transverse band about one and one-half a scale long at midbody; (6) hemipenis simple, sybcylindrical, unicapitate, and unicalyculate, calyces large, well defined, papillate, with a set of 12 large spines just proximate to the capitulum on the asulcate side, and a centrolineal sulcus spermaticus bifurcating at the distal tip of the capitulum; (7) distribution in remnants of the Atlantic Rainforest in northeastern Brazil.

Description of the holotype: Adult male, SVL 595 mm, TL 445 mm (74.8% of SVL); head length 22.2 mm (3.7% of SVL); body diameter 12.5 mm (2.1% of SVL); head width 11.7 mm (52.7% of head length); interorbital distance 9.8 mm; rostro-orbital distance 6.5 mm (66.3% interorbital distance); naso-orbital distance 5.1 mm; head distinct from body, slightly arched in lateral view, elliptical in dorsal view; snout truncate in lateral and dorsal views ( Fig. 2 A–B); rostral semilunar, barely visible in dorsal view; internasal 3.1 mm long, 3.5 mm wide; prefrontal 3.2 mm long, 3.5 mm wide; supraocular elongate in dorsal view, 6.4 mm long, 3.1 mm wide; frontal subtriangular in dorsal view, 6.8 mm long, 2.4 mm wide; parietal 7.7 mm long, 5.2 mm wide; nasal divided; nostril located between prenasal and postnasal; prenasal twice higher than long; postnasal similar in height to prenasal, slightly longer than high; loreal 2.5 mm long, 1.6 mm high; eyes large, eye diameter 4.2 mm, pupil round; two preoculars, the upper 3.0 mm high, 2.1 mm wide, distinctly larger than lower; two postoculars; upper postocular taller (2.6 mm) and longer (1.1 mm) than lower postocular; temporals 2+2; anterior upper temporal 2.4 mm long, 1.3 mm high; first inferior temporal 5.2 mm long, 1.8 mm high; upper posterior temporal elongate, 3.7 mm long, 1.2 mm wide; inferior posterior temporal 2.6 mm long, 1.3 mm wide; 9–9 supralabials, fourth to sixth contacting the eye; mental triangular, 3.0 mm width, broader than long ( Fig. 2 C); 9–9 infralabials, first to fifth contacting the anterior chinshield, posterior part of fifth and sixth contacting the posterior chinshield; first pair of infralabials in contact behind mental, preventing contact between mental and chinshields; anterior chinshields 4.6 mm long, 1.8 mm wide; posterior chinshields 7.6 mm long, 2.1 mm wide; one pair of gular scales; two preventrals. Dorsal scales carinate, with paired apical pits on some of them; dorsals in 17–17–15 rows; 154 ventrals; cloacal scute single; 152 divided subcaudals; dorsocaudal scale reduction from eight to six posterior to subcaudal 32.

In life ( Fig. 1 ), head uniformly brown; collar absent; dorsum brown, paler on anterior third, with transverse cream markings one half a scale long, bordered anteriorly and posteriorly by dark brown lines one half scale long, distributed from the neck to the tail; in some parts of dorsum, these lines are interrupted in the middle and the patterned scales of each lateral line are disposed alternately; infralabials cream; ventral scutes cream with lateral margins dark brown due to the extension of the dorsal color. In preservative, the dorsal color is brownish gray with transverse markings white bordered by black and the venter is cream.

Retracted hemipenis bifurcates and extends to the level of the eighth subcaudal scale. Everted organ ( Fig. 3 A– B) single, subcylindrical, unicapitate, and unicalyculate; capitular groove distinct on both sides of the organ; capitulum about one third of the length of the entire organ; calyces large, well defined, papillate; a group of 12 large spines just below the capitulum, on the asulcate and on the lateral side; a group of small spines on the distal portion and a series of four spines, two large laterals and two small between them, in the basal region of the asulcate side of the organ body; on the sulcate side, the organ body presents medium sized spines just below the capitulum and two large spines on the lateral distal areas; sulcus spermaticus deep, with margins thick, smooth; sulcus spermaticus centrolineal, bifurcating at the tip of the capitulum and each small branch ending in small reentrances.

Variation among paratypes: There is little variation among the paratypes, primarily in some scales counts. There are 9–9 or 9–10 supralabials, 9–9 or 9–10 infralabials, 154–157 ventrals in males and 157–163 in females, and 140–160 subcaudals in males and 145–153 in females. Maximum total length (SVL plus TL) is 1162 mm in males and 1024 mm in females.

Comparison with other members of the Dendrophidion dendrophis group: Dendrophidion atlantica can be distinguished from D. dendrophis (characteristics of D. atlantica followed by those of D. dendrophis , in parentheses) by having a lower number of subcaudal scales (140–160 vs. 171–195; Lieb 1988), a shorter tail (mean TL 40.4% of total length in males and 41.2% in females vs. 44.9% in males and 45.1% in females; Prudente et al. 2007), narrower transverse white markings and dark brown crossbands (one half and one and one half a scale long, respectively, vs. about one and two scales long, respectively; Lieb 1988), hemipenis unicalyculate vs. flounced, with a group of 12 large spines just proximate to the capitulum vs. 10 spines, and a group of four spines (two large lateral spines with two smaller ones between them) on the basal portion of the sulcate side of the hemipenial body vs. a group of three spines (two very large lateral spines with one slightly smaller one between them). Dendrophidion atlantica is distinguished from D. nuchale by having white and dark brown markings the length of the body vs. having the anterior third of the body paler and patternless and the posterior third darker and patterned usually with rows of pale yellow ocelli ( Lieb 1988) and a hemipenis with small basal spines vs. two to four large basal spines ( Lieb 1988). Dendrophidion atlantica is differentiated from D. vinitor by having a higher number of subcaudal scales (140–160 vs. 111–128; Lieb 1988), narrow pale markings on the body vs. broad pale crossbands on the anterior portion of the body, and a hemipenis with basal spines vs. elongate, hooked villi on the proximal portion; Lieb 1988).

Habitat and habits: We observed and/or collected 41 specimens of D. atlantica sp. nov., 35 of them inside forest and six on its border. All specimens were found on the litter, except one observed descending from a small tree to the ground. Inside the forest or on the border, the specimens always were found in the shade during the day between 07h30min to 17h50min, with a peak of activity between 10h45min and 14h09min.

All specimens, when located, remained motionless. When approaching to collect them, they made rapid movements, giving the impression that they were moving far away, but actually the snakes had moved only one or two meters ahead, becoming motionless again. When captured, the snake contorted the body and discharged cloacal material. Seven specimens autotomised their tails during capture, and five succeeded in escaping using this defense mechanism.

Geographical distribution: Known from five localities in the State of Alagoas, Brazil, all associated with the Atlantic Rain Forest biome ( Fig. 4 ).

Etymology: The specific name, used as a noun in apposition, is an allusion to the disjunct occurrence of this new species in the Atlantic Rain Forest.

Figures

FIGURE 1. General view in life of the holotype of Dendrophidion atlantica sp. nov. (MNRJ 17018; SVL 595 mm).

FIGURE 2. Lateral (A), dorsal (B), and ventral (C) views of the head of Dendrophidion atlantica sp. nov. (holotype, MNRJ 17018). Bar equals 10 mm.

FIGURE 3. Sulcate (A) and asulcate (B) views of the hemipenis of Dendrophidion atlantica sp. nov. (holotype, MNRJ 17018). Bar equals 5 mm.

FIGURE 4. Distribution of Dendrophidion atlantica sp. nov. in the State of Alagoas, Brazil. 1: Mata do Catolé, Maceió; 2: Mata da Salva, Rio Largo; 3: Mata do Rio Messias, Messias; 4: Mata da Bananeira, Murici; 5: Mata do Engenho Coimbra, Ibateguara (type locality).