Dendrelaphis binhi, Nguyen & Nguyen & Le & Nguyen & Vo & Vo & Che & Murphy, 2023

Nguyen, Sang Ngoc, Nguyen, Vu Dang Hoang, Le, Manh Van, Nguyen, Luan Thanh, Vo, Thi-Dieu-Hien, Vo, Ba Dinh, Che, Jing & Murphy, Robert W., 2023, A new snake of the genus Dendrelaphis Boulenger, 1890 (Squamata: Colubridae) from the coastal area of southern Vietnam, Zootaxa 5318 (1), pp. 130-144 : 136-139

Dendrelaphis binhi sp. nov.

Holotype. ITBCZ 6663 , adult male, collected from Tuy Phong , Binh Thuan Province, Vietnam; coordinates 11 o 12’36.2”N, 108 o 41’43.2”E; elevation 34 m a.s.l. by S.N. Nguyen and L. T. Nguyen, on 23 July 2018 ( Figs. 3 & 4 ).

Paratypes. Seven specimens: ITBCZ 6664 , ITBCZ 6666 (adult females), ITBCZ 6665 (subadult male), collected by the same collectors, on the same date and site as the holotype; ITBCZ 6681 (adult male), collected from Tuy Phong, Binh Thuan Province, Vietnam, coordinates 11 o 13’03.3”N, 108 o 39’10.2”E, elevation 39 m a.s.l. by S.N. Nguyen and L. T. Nguyen, on 26 July 2018; ITBCZ 5944-6 (adult females), collected from Thuan Nam, Ninh Thuan Province, Vietnam; coordinates 11 o 19’18.4”N, 108 o 56’46.6”E; elevation 105 m a.s.l. by S.N. Nguyen and D.H. V. Nguyen, on 13 April 2017 ( Figs. 3–5 ) .

Diagnosis. Dendrelaphis binhi sp. nov. is distinguished from all of its congeners by a combination of the following morphological characters: medium sized bronzeback snake (largest TL 936 mm in female); one long supralabial entering orbit; body scale smooth, 13 rows on neck and midbody, 9–11 before vent; vertebral scale row slightly enlarged; ventrals 154–158 in males and 161–170 in females; subcaudals 105 or 106 in males and 95–102 in females; 18 or 19 maxillary teeth, posterior teeth shorter than the others; hemipenis spinose, reaching 10 th or 11 th SC, with a tiny papilla; cloacal plate divided; dorsum bright brown with a white stripe along the lower flank.

Description of holotype. Adult male; head elongate (HL/HW = 1.99), distinct from neck; body elongate, SVL 495 mm; tail long (TaL/TL = 0.305), 217 mm in length; eye quite large with round pupil, eye diameter shorter than snout length (ED/SnL: 0.76) ( Table 3 ).

Head scalation. Dorsal head scales smooth, abutting along midline rather than overlapping; rostral broader than high, visible from above, touching nasals, internasals and 1 st supralabial on both sides; supralabials 8/8, first fours small, the 5 th bordering eye on both sides, the 6 th small and triangle shaped, the 7 th and 8 th distinct larger than the 6 th and the first fours; 1/1 loreal, much longer than high (2.0 mm length vs. 0.8 mm height), touching nasal, internasal, prefrontal, preocular and the 2 nd and 3 rd supralabials; 1/1 preocular; 2/2 postoculars; 2+2/2+2 temporals; suture between internasals as long as that between prefrontals; frontal bell-shaped, widened anteriorly and much narrowed posteriorly (5.6 mm length, 3.6 mm width); parietals longer than frontal (6.5 mm vs. 5.6 mm length), bordered laterally by upper temporals and postocular and anteriorly by frontal and supraoculars; 10/10 infralabials, first pair medially in contact with each other, first five in contact with anterior chin shield, the 6 th largest and touching posterior chin shield; posterior chin shields slightly longer than anterior ones (5.1 mm vs. 4.9 mm) ( Fig. 4A ).

Body scalation. Dorsal scales smooth, in 13-13-9 rows; lateral scales, except for the outer row, disposed obliquely; vertebral scale row slightly enlarged, narrower than the outer row of scales; scale row reductions from 13 to 11 at ventrals 89 and 90 and from 11 to 9 at ventrals 96 and 99; ventrals 158, with a suture-like lateral keel; cloacal plate divided; subcaudals 106, all paired; terminal caudal scale forming a pointed cap.

Dentition. Maxillary teeth 18, continuously, the posterior teeth slightly smaller than the others.

Hemipenis. Hemipenis unforked, reaching 11 th SC, spinose throughout, except for the apical naked area. The spines in the terminal half of the organ are largest. Sulcus spermaticus single, extending to tip, the sulcus lip prominent. On the apical naked area, there is a tiny lobule with small spines ( Fig. 4B&C ).

Coloration. In life, dorsal and lateral parts of the body and tail bronze-brown, laterally this color extends to the upper half of the second scale row; upper part of head olive, lip and lower parts of the head and neck yellow; iris orange on the upper part and black on anterior, posterior, and lower parts of the eye; concealed parts of lateral scales light blue; a black temporal streak extending from eye to neck; a bright vertebral stripe on the anterior part of dorsum; two lateral stripes: a white one on the lower half of the second scale row and the upper half of the outer row and the second stripe is pale brown occurring on the lower half of the outer row and the edge of ventral scale; anterior part of the body with a series of black blotches at the suture between the lateral edge of ventral and the outer row, these blotches are less distinct or absent on the middle and posterior parts of the body; ventral white. In preservation, color faded but the pattern remained, all yellow parts becoming white.

Variation. Paratypes ITBCZ 6665 and ITBCZ 5945 have 7 and 9 supralabials on the right side, respectively; paratypes ITBCZ 5945 and ITBCZ 5946 have 11 dorsal scale rows before vent; paratype ITBCZ 5946 has a short suture on the lower margin of the 5 th supralabial on both sides; paratype ITBCZ 5945 has the upper half of the second dorsal row black forming a black longitudinal line ( Fig. 3E ); lip and lower parts of head and neck yellow in all specimens collected in July in Tuy Phong, Binh Thuan Province but white in all snakes collected in April in Thuan Nam , Ninh Thuan Province. Table 3 summarizes variation in size and scalation of type series.

Sexual dimorphism. Male has fewer ventral scales (V 154–158 in 3 males, 161–170 in 5 females) and slightly longer relative tail (TaL/TL 0.305–0.309 in 2 adult males; 0.277–0.297 in 5 adult females).

Etymology. We name the new species in honor of Dr. Ngô Văn Bὶnh, a Vietnamese herpetologist who passed away suddenly in 2023 at the age of 49 by a serious stroke. We recommend “Binh’s Bronzeback Snake” and “Rắn leo cây bὶnh” as the common English and Vietnamese names of the new species, respectively.

Distribution. The new species is currently known from Thuan Nam, Ninh Thuan Province and Tuy Phong, Binh Thuan Province, Vietnam ( Fig. 1 ).

Field notes. All specimens were collected at night, between 7:00 PM and 11:00 PM, while sleeping on brushes at about 1–2 m above ground. The habitat in Thuan Nam , Ninh Thuan Province is a coastal hill with brushes and granite outcrops ( Fig. 5B ) and the habitat in Tuy Phong , Binh Thuan Province is an agricultural area with scattered large brushes. The holotype was collected on a large brush group together with paratypes ITBCZ 6664 and ITBCZ 6665 and with two other individuals of Ahaetulla fusca (Dumeril, Bibron & Dumeril) . Gravid paratype ITBCZ 5946 has three eggs.

Comparisons. Dendrelaphis binhi sp. nov. differs morphologically from all congeners in Indochina as follows: from D. biloreatus (Wall, 1908) by having fewer ventrals (154–170 vs. 187–199), fewer subcaudals (95–106 vs. 139–145), one (vs. two) supralabial entering the eye, and vertebral scale row slightly enlarged (vs. strongly enlarged) ( Smith 1943); from D. caudolineatus by having fewer ventrals in males (154–158 vs. 171–180), fewer ventrals in females (161–170 vs. 171–185), one (vs. two) supralabial entering the eye, and absence (vs. presence) of black longitudinal stripes along the entire length of the body ( Rooijen & Vogel 2012); from D. cyanochloris (Wall, 1921) by having fewer midbody scale rows (13 vs. 15), fewer ventrals (154–170 vs. 181–206), fewer subcaudals (95–106 vs. 135–157), one (vs. two) supralabial entering the eye, and vertebral scale row slightly enlarged (vs. strongly enlarged) ( Rooijen & Vogel 2008; Jiang et al. 2020); from D. formosus by having fewer midbody scale rows (13 vs. 15), fewer ventrals (154–170 vs. 172–194), fewer subcaudals (95–106 vs. 142–162), and one (vs. two) supralabial entering the eye ( Jiang et al. 2020); from D. haasi by having fewer midbody scale rows (13 vs. 15), one (vs. two) supralabial entering the eye, and vertebral scale row slightly enlarged (vs. strongly enlarged) ( Das 2015); from D. kopsteini Vogel & Van Rooijen, 2007 by having fewer midbody scale rows (13 vs. 15), one (vs. two) supralabial entering the eye, and vertebral scale row slightly enlarged (vs. strongly enlarged) ( Vogel & Rooijen 2007); from D. ngansonensis by having fewer subcaudals (95–106 vs. 117–153), one (vs. two or three) supralabial entering the eye, vertebral scale row slightly enlarged (vs. strongly enlarged), fewer maxillary teeth (18 or 19 vs. 24 or 25), and shorter hemipenis (extending to SC 10 or 11 vs. SC 18) ( Ziegler & Vogel 1999; Jiang et al. 2020); from D. nigroserratus Vogel, Rooijen & Hauser, 2012 by having fewer midbody scale rows (13 vs. 15), fewer ventrals (154–170 vs. 197– 204), fewer subcaudals (95–106 vs. 148–152), one (vs. three) supralabial entering the eye, and vertebral scale row slightly enlarged (vs. strongly enlarged) ( Vogel et al. 2012); from D. pictus by having fewer midbody scale rows (13 vs. 15), fewer subcaudals (95–106 vs. 113–148), fewer maxillary teeth (18 or 19 vs. 23–28), one (vs. two or three) supralabial entering the eye, and vertebral scale row slightly enlarged (vs. strongly enlarged) ( Smith 1943; Vogel & Rooijen 2008); from D. striatus by having fewer midbody scale rows (13 vs. 15), one (vs. two or three) supralabial entering the eye, and absence (vs. presence) of black oblique bars laterally on the body ( Ziegler & Vogel 1999; Vogel & Rooijen 2007); from D. subocularis by having fewer dorsal scale rows at neck (13 vs. 15) and at midbody (13 vs. 15), and fewer maxillary teeth (18 or 19 vs. 21–23) ( Smith 1943; Rooijen & Vogel 2010); from D. tristis by having fewer midbody scale rows (13 vs. 15), fewer subcaudals (95–106 vs. 108–145), one (vs. two) supralabial entering the eye, and longer hemipenis (extending to SC 10 or 11 vs. SC 8) ( Smith 1943); from D. vogeli by having fewer midbody scale rows (13 vs. 15), one (vs. two) supralabial entering the eye, fewer ventrals (154–170 vs. 193–197), fewer subcaudals (95–106 vs. 130–135), and vertebral scale row slightly enlarged (vs. strongly enlarged) ( Jiang et al. 2020); and from D. walli Vogel & Rooijen, 2011 by having fewer ventrals (154–170 vs. 193–197), fewer subcaudals (95–106 vs. 130–135), one (vs. two) supralabial entering the eye, and vertebral scale row slightly enlarged (vs. strongly enlarged) ( Vogel & Rooijen 2011).

Figures

FIGURE 1. Map showing the distribution of Dendrelaphis binhi sp. nov. (triangles) and D. subocularis (dots) in Vietnam. 1, Chi Linh, Hai Duong Prov.; 2, Chu Lai, Quang Nam Prov.; 3. Khanh Hoa Prov.; 4, D’ran, Lam Dong Prov.; 5, Phan Rang, Ninh Thuan Prov.; 6, Thuan Nam, Ninh Thuan Prov.; 7, Tuy Phong, Binh Thuan Prov.; 8. Binh Chau, Ba Ria—Vung Tau Prov.; 9, Tan Bien, Tay Ninh Prov.

FIGURE 3. Dendrelaphis binhi sp. nov. A–D, holotype ITBCZ 6663. A, specimen at its sleeping position in situ; B, dorsal view; C&D, dorsal and ventral views of fresh specimen; E, patatype ITBCZ 5945 and F, unvoucher specimen at their sleeping positions in situ, respectively.

FIGURE 4. Dendrelaphis binhi sp. nov. A, drawing of head scalation (scale bar 5 mm) of the holotype ITBCZ 6663; B&C, sulcal and asulcal views of hemipenis of the holotype ITBCZ 6663, respectively; D, hemipenes of paratype ITBCZ 6665; E, maxillary teeth of paratype ITBCZ 5945.

FIGURE 5. Dendrelaphis subocularis, Dendrelaphis binhi sp. nov. and habitat of the latter. A, drawing of D. subocularis (upper) extracted from original description (Boulenger 1888) and paratype ITBCZ 6666 (lower) showing a series of black blotches on the suture between the lateral edge of ventral and the outer row on the anterior part of body; B, habitat of the new species in Thuan Nam, Ninh Thuan Province, southern Vietnam.