Trimeresurus uetzi, Vogel & Nguyen & David, 2023

Vogel, Gernot, Nguyen, Tan Van & David, Patrick, 2023, A new green pitviper of the Trimeresurus albolabris complex (Reptilia, Serpentes Viperidae) from central and southern Myanmar, Zootaxa 5357 (4), pp. 515-554 : 518-530

Trimeresurus uetzi sp. nov.

( Fig. 2–4 ; Tables 1–2 )

Trimeresurus gramineus (non Coluber gramineus Shaw, 1802 ) – Günther (1864: 335; in part); Theobald (1868: 63 [as Trimesurus [sic] gramineus ], 1882: 313; both in part); Wall (1925a: 250, in part; 1925b: 821; 1926: 566); Rendahl (1937: 27; in part); Hundley (1964a: 24; in part). Lachesis gramineus – Boulenger (1896: 554; in part).

Trimeresurus albolabris (non Trimesurus albolabris Gray, 1842 ) – Boulenger (1893: 309 & 328); Pope & Pope (1933: 9; in part); Smith (1943: 523, in part); Hundley (1964b: 7; in part); Regenass & Kramer (1981: 168 & 169, in part); Dowling & Jenner (1988: 6); Toriba in Golay et al. (1993: 95, in part); Zhao & Adler (1993: 275; in part); Manthey & Grossmann (1997: 407, in part); David & Ineich (1999: 280, in part, & 371); McDiarmid et al. (1999: 329, in part); Orlov et al. (2002a: 189, 2002b: 351; both in part); Leviton et al. (2003: 444, in part, 462); Gumprecht et al. (2004: 30, in part); Vogel (2006: 83, in part); Whitaker & Captain (2008: 464); Chakma in Kabir et al. (2009: 174; in part); Stuart et al. (2012: 1, in part); Wallach et al. (2014: 726, in part); Guo et al. (2015: 268); Visser (2015: 242; in part); Zhu et al. (2016: 253, 256, 258 & 259, in part); Mirza et al. (2020: 124, in part); Zug & Mulcahy (2020: 85 & 164, in part); Chen et al. (2021: 119); Rathee et al. (2022: 2, in part); Uetz et al. (2023, page “ Trimeresurus albolabris ”, in part).

Trimeresurus albolabris albolabris – Regenass & Kramer (1981: 168 & 169, in part); David & Tong (1997: 26, in part).

Cryptelytrops albolabris – Leviton et al. (2008: 71, in part); Das (2010: 303; 2012: 71; 2018: 137, all in part).

Trimeresurus cf. albolabris – Mallik et al. (2021: 580; specimen CAS 232480).

Trimeresurus septentrionalis (non Trimeresurus septentrionalis Kramer, 1977 ) – Guo et al. (2015: 269, specimens from Myanmar), Zhu et al. (2016: 254, specimens from Myanmar), Mirza et al. (2023: 94, specimens from Myanmar), Elangbam et al. (2023: 23319, specimens from Myanmar).

Holotype: CAS 243024 , an adult male from Mauk Village , Gangaw Township, Pakhokku District, Magway Region, Myanmar (22.3490000000°N, 94.1537777778°E; altitude ca. 185 m a.s.l); collected by M. Win, Z.H. Aung, and K.T. Kyaw on 26 August 2008.

Paratypes (n = 8; for detailed information see Appendix IV): Myanmar. Chin State: CAS 234852 (adult female) ; Mandalay Region: CAS 232480 (adult male), CAS 210691 (adult female) ; Magway Region: CAS 243055 (adult male) ; Sagaing Region: CAS 210109 , CAS 215472 , CAS 215540 (three adult females) ; Shan State: CAS 235954 (adult female) .

Additional materials (n= 16; for detailed information see Appendix IV): Myanmar. Chin State: CAS 220124 (subadult male), CAS 235958 (subadult female) ; Mandalay Region: CAS 204846–204847 , CAS 210665 , CAS 246991 (four adult males); CAS 210690 , CAS 214110 (two adult females) ; Magway Region: CAS 215907 , CAS 243159 (two adult males), CAS 213722 , CAS 246953 , CAS 242985 (three adult females) ; Bago Region: CAS 242723 (adult male) ; Sagaing Region: CAS 215400 , CAS 215343 (two adult females) .

Etymology. The species epithet is an eponym coined in honour of Peter Uetz, the editor of the “ Reptile Database ” website, for his invaluable help to herpetologists.

Diagnosis. This species is recognized by (1) dorsal colouration grass-green or deep green with faint transverse dark bands across the dorsum; (2) venter uniform yellowish-green; (3) side of the head grass-green or deep green above the level of the lower margin of eyes, yellowish-green below; (4) white postocular stripe present males; (5) in males, a yellowish-green ventrolateral stripe present, narrow, only extending on the outermost row of dorsal scales; stripe absent in females; (6) iris copper in male or green gold in female; (7) first supralabial not fused with nasal scale or barely fused with a suture visible; (8) cephalic scales feebly keeled; (9) dorsal scales arranged in 21–21–15 rows, moderately keeled except the outermost rows; (10) ventral scales: 154–171 in males, 157–171 in females; (11) subcaudal scales: 61–71 in males, 50–55 in females; (11) hemipenes short, reaching only the 6 th –8 th subcaudals when everted or in situ, covered with relatively weak and sparse papillae.

Description of the holotype ( Fig. 2 ).

Morphology. Body cylindrical, long, and thin (SVL 472 mm, TaL 119 mm, TL 591 mm, ratio TaL/TL 0.20). Head triangular in dorsal view, elongate, clearly distinct from the neck (HL 23.6 mm, HW 13.5 mm, HW/HL 1.75), snout elongate, flattened, and rounded when seen from above, rather rectangular when seen from lateral side, with a very distinct and sharp canthus rostralis; loreal pit present. Eye average (ED 3.12 mm, EN 4.85 mm, ratio ED/SN 0.65); pupil vertically elliptic.

Body scalation. Dorsal scales in 21–21–15 rows; dorsal scales all moderately keeled, except the first row of which scales are smooth; 167 ventrals (plus 2 preventrals); cloacal plate single; 69 subcaudals, all divided.

Head scalation. Rostral slightly visible from above, triangular; one large pair of enlarged internasals, in contact each with the other; nostril completely included in nasal scale; nasal scale partially fused with the first supralabial, separated by a suture present behind the nostril, but not present anteriorly; foveal scale bordering the anterior edge of the pit fused with the second supralabial; a small scale between the nasal and the foveal; scales on the upper snout surface and in the interorbital region smooth, irregular, barely imbricate; temporal and occipital scales moderately keeled. Two elongate upper preoculars above the loreal pit; lower preocular forming the lower margin of the loreal pit. One supraocular on each side, large, broader than the internasals; 10 irregular cephalic scales (Cep) between the supraoculars; one long, thin, crescent-like subocular scale; 10/11 supralabials, third largest and in contact with the subocular, 4 th and 5 th supralabials separated from subocular by one row of scales, 6 th supralabial separated by 2/2 scales; 2/2 postoculars; 12/12 infralabials, those of the first pair in contact with each other behind the mental, the first three pairs in contact with the single pair of chin shields. Five pairs of gulars aligned between the chin shields and the 1 st preventral.

Hemipenis. The organ is relatively short, thin, papillose, deeply forked with small, soft, basal spines, reaching only the 6 th SC.

Coloration in preservative ( Fig. 2 ): Body dark greyish-brown above with faint darker dorsal crossbands due to regular areas of darker skin, uniform pale greenish-blue on its lower sides; a white, conspicuous ventrolateral stripe extends on the 1 st dorsal scale row from the neck to the base of the tail. Ventral surface uniform pale yellowish-green. The dorsal surface of the tail is like that of the body or slightly more blue. The head is dark greyish-brown on its dorsal and upper lateral surfaces; rostral and nasal scale dark greyish-brown; upper part of 1 st supralabial cream; a cream-colored streak extends along the head from the lower edge of the loreal pit to the lower margin of the eye, the subocular scale, the upper part of the 3 rd supralabial and the scales separating the supralabials from the subocular; behind the level of the head, a thicker and more conspicuous postocular streak extends from the posterior margin of the eye to the corner of the mouth and behind where it connects with the ventrolateral stripe; supralabials dark greenish-blue, irregularly mottled with greenish-yellow; the dark and paler colors of the sides of the head are sharply separated by the white lateral streak. The chin and throat are uniform creamish-yellow but mental scales and first infralabials ornate with dark greenish-blue.

According to CAS staff, no photographs of living specimens of the type series of Trimeresurus uetzi sp. nov. were taken .

Variation (see Table 1 and Fig. 3 for the details). The longest known specimen is 811 mm long (SVL 689 mm, TaL 122 mm, female; CAS 235954 ). The longest known male is 591 mm long (SVL 472 mm, TaL 119 mm; CAS 243024 ). Ratio TaL/TL: 0.141 –0.222 (males: 0.161 –0.222, females: 0.141 –0.157).

Body scalation. 21(rarely 19, 22 or 23) – 21(rarely 19) – 15 (rarely 13) DSR; 154–172 VEN, without sexual dimorphism; 50–71 SC (males: 60–71, females: 50–55); Total VEN +SC: 209–240 (males: 216–240, females: 209– 223).

Head scalation. InSep: none, internasals in contact in all known specimens; Cep: 9–10; SL: 10–12 (exceptionally 9); IL: 11–14.

Main characters of pattern. Postocular streak always present, white, thick, and conspicuous in males, absent or white, thin and faint; ventrolateral stripe always present, white and conspicuous in males, absent or white, thin in females.

Hemipenis. The organ is relatively short, thin, papillose, deeply forked with small, soft, basal spines, reaching only the 6 th –8 th SC (based on two specimens, namely the holotype CAS 243024 and specimen CAS 243005 , paratype).

Coloration in life ( Fig. 4 ). The description is based on photographs of males of the species Trimeresurus uetzi sp. nov. from Myanmar via Native Species Conservation and Identification in Myanmar (https:/www.facebook.com/ groups/nscimy) and photos published in Leviton et al. (2003, 2008). The upper head surface and temporal regions are of the same color than dorsal surface; supralabials paler than the body; postocular streak in male always white ore cream (absent in female); white ventrolateral stripe well developed, highly contrasted, covering approximately two - third of the height of the first dorsal scale row, increasing in width towards the head in male; ventrolateral stripe at best thin in females. The venter, chin and throat are uniformly yellowish-green but paler than the body. Iris copper in males or greenish-gold in females.

Comparison. We summarize in Table 2 the main characters separating Trimeresurus uetzi sp. nov. from the other twelve species of the complex of Trimeresurus albolabris- septentrionalis . More specifically, the comparisons with these species are as follows:

Trimeresurus uetzi sp. nov. is distinguished from T. albolabris sensu stricto (restricted to southern China, northern Vietnam and central Laos) by having: (1) hemipenes short, reaching only the 6 th –8 th SC vs. reaching the 15 th –18 th SC in T. albolabris ; (2) higher mean number of ventral scales (163.27 ± 5.61 in males, 164.14 ± 3.84 in females vs. 154.93 ± 4.67 in males, 158.80 ± 4.78 in females, respectively); (3) greater mean total numbers of ventral scales plus subcaudals in males (230.4 ± 7.88 vs. 218.00 ± 11.04); (4) no small scale between the nasal and the pit vs. one or two small scales usually present; and (5) postocular streak paler and wider covering 2–3 scales in males vs. thinner, covering 1–2 scales. Furthermore, T. uetzi sp. nov. is widely separated from T. albolabris sensu stricto on a geographical basis as this latter species inhabits only south-eastern China, northern Vietnam and central Laos. Moreover, the ranges of both species are separated by that of Trimeresurus guoi .

Trimeresurus uetzi sp. nov. is distinguished from T. caudornatus by having: (1) tip of hemipenes reaching the 6 th –8 th SC vs. 37 th –38 th SC; (2) postocular stripe present in males vs. absent; (3) ventrolateral body stripe present, white, conspicuous vs. faint, greenish-yellow, poorly contrasted; (4) in life, iris copper in male vs. golden yellow in male; and (5) no median stripe on the lower surface of the tail vs. an irregular, red-orange stripe in the middle of the ventral surface present.

Trimeresurus uetzi sp. nov. is distinguished from T. guoi by having: (1) hemipenes reaching the 6 th –8 th SC vs. the 23 rd –32 nd SC; (2) ventrolateral stripes present in males and often in females vs. absent in both sexes; (3) a postocular stripe present in males vs. absent; and (4) in life, iris copper in male vs. firebrick-red or deep red in male.

Trimeresurus uetzi sp. nov. is distinguished from T. salazar by having: (1) hemipenes reaching the 6 th –8 th SC vs. 12 th –13 th SC; (2) postocular streak white vs. bicolor (red and white); (3) ventrolateral stripe white vs. stripe bicolor (red and white); and (4) lower total numbers of ventral scales and subcaudals in females 216.08 ± 3.99 vs. 227.33 ± 3.79.

Trimeresurus uetzi sp. nov. is distinguished from T. septentrionalis sensu stricto, restricted to western and central Himalayan regions of Nepal and northern India, two species previously largely confused, by having: (1) lower total of ventral scales and subcaudals (230.4 ± 7.88 in males, 216.08 ± 3.99 in females vs. 241.67 ± 7.76 in males, 231.79 ± 3.68 in females of T. septentrionalis ); (2) white postocular streak wide and conspicuous, covering 2–3 scales in males vs. usually absent or thin and pale, covering 1 scale; and (3) in life, eye copper in male vs. yellowish-green in male.

Trimeresurus uetzi sp. nov. is distinguished from T. erythrurus (Cantor) , a species sympatric in Myanmar, by having: (1) lower number of midbody dorsal scale rows, 21 vs. usually 23 rows; (2) dorsal scales moderately keeled vs. strongly keeled; (3) temporal scales barely keeled vs. strongly keeled and tuberculate; and (4) hemipenes reaching the 6 th –8 th SC vs. 20 th –25 th SC.

Among other species of the Trimeresurus albolabris complex of species living out of Myanmar and of the Indochinese region, the new species can be separated as follows:

Trimeresurus uetzi sp. nov. is distinguished from T. andersoni Theobald by having: (1) grass-green or deep green dorsal coloration vs. predominantly brown in T. andersoni ; (2) lower number midbody dorsal scales, 21 in all known specimens vs. 23–25; and (3) lower total number of ventral scales plus subcaudals in females, namely 209–223 vs. 232.

Trimeresurus uetzi sp. nov. is distinguished from T. cantori (Blyth) by having (1): grass-green or deep green dorsal coloration vs. brownish-grey; (2) ventral color yellowish-green vs. cream with black spots; (3) lower number of midbody scale rows, 21 vs. 25–29; (4) lower total of ventral scales and subcaudals (230.4 ± 7.88 in males, 216.08 ± 3.99 in females vs. 243.75 ± 4.06 in males, 233.61 ± 5.49 in females), (5) hemipenes reaching the 6 th –8 th SC vs. 16 th –20 th SC.

Trimeresurus uetzi sp. nov. is distinguished from T. davidi Chandramouli, Campbell & Vogel by having: (1) ventrolateral stripes present in males vs. entirely absent; (2) lower mean number of subcaudals in males (52.08 ± 1.62 vs. 61.13 ± 3.31); and (3) lower total number of ventral plus subcaudal scales, namely 230.4 ± 7.88 in males, 216.08 ± 3.99 in females vs. 241.00 ± 2.65 in males, 232.13 ± 5.99 in females, respectively.

Trimeresurus uetzi sp. nov. is distinguished from the Indonesian species T. fasciatus (Boulenger) by having: (1) green dorsal coloration vs. brownish-grey; and (2) dorsal pattern uniform or very faintly banded due to darker areas of the interstitial skin vs. strongly banded with darker brown on scales; and (3) ventral color yellowish-green vs. dark brown.

Trimeresurus uetzi sp. nov. is distinguished from the other Indonesian species T. insularis Kramer by having: (1) iris copper in male vs. usually deep red or fire red in male; (2) temporal scales feebly keeled vs. strongly keeled, and (3) hemipenes reaching the 6 th –8 th SC vs. 23 th SC.

Trimeresurus uetzi sp. nov. is distinguished from T. purpureomaculatus (Gray) , as currently defined, by having: (1) lower number of dorsal scale rows at midbody, 21 vs. usually 25 (rarely 27 or 29); (2) green dorsal coloration vs. uniform black to olive, greenish/yellowish, brownish-red or grey, with or without dark blotches; (3) dorsal scales moderately keeled vs. strongly keeled; (4) temporal scales barely keeled vs. strongly keeled; and (5) tip of hemipenes reaching only the 6 th –8 th SC vs. reaching 16 th –20 th SC.

Distribution range ( Fig. 5 ). Currently, Trimeresurus uetzi sp. nov. is known only from central and southern Myanmar: regions of Mandalay, Sagaing, Magway, Bago, and Chin and Shan states; see detail in Appendix IV). Further studies in neighboring areas, especially in southeastern Myanmar, such as other parts of Shan and Kayah States, are required to determine the actual distribution and population trend of this species.

Natural history notes. According to data recorded for specimens deposited in the collections of CAS (see Appendix IV), specimens of Trimeresurus uetzi sp. nov. were collected both during the day and at night perched on trees or shrubs, branches or on the ground under bamboo clump. The air temperature varied from 21.7°C to 32.0°C (71–89.6°F), and relative humidity 67–91%. This species seems to be distributed from low and medium elevations, namely from nearly sea level to 1,746 m a.s.l. Further investigations of the behavior, diet and reproductive habits of the new species are required. The smallest specimen at hand has a body length of 242 mm with an incomplete tail and was collected on 17 th of July at Chin State: Falam Township, Laiva Protect Forest Reserve, and Laiva Dam (CAS 235958).

Figures

FIGURE 2. Trimeresurus uetzi sp. nov. in preservative, specimen CAS 243024, Holotype, male. A. General dorsal view. – B. General ventral view. – C. Lateral view of the head, right side. – D. Lateral view of the head, left side. – E. Dorsal view of the head. – F. Ventral view of the head. – G. Ventral view of the tail with the everted hemipenes. – H. Dorsal view of the base of the tail. Photos by G. Vogel.

FIGURE 3. Lateral view of the head, right & left side, respectively of the Trimeresurus uetzi sp. nov. in preservative: A & B. Specimen CAS 232480 (paratype, male); C & D. Specimen CAS 243055 (paratype, male); E & F. Specimen CAS 242723 (male); G & H. Specimen CAS 210109 (paratype, female); I & J. Specimen CAS 215472 (paratype, female); K & L. Specimen CAS 215540 (paratype, female). Photos by G. Vogel.

FIGURE 4. Trimeresurus uetzi sp. nov., in life. A. Myanmar (no specific locality). – B. Yesagyo, Magway Region, Myanmar. – C & D. Popa Mountain, Mandalay Region, Myanmar. – E & F. Kandaw, Myingchan, Mandalay Region, Myanmar. Photos by A: Hla Tun (CAS-NWCD), B: Myo Mint Oo, and C: Drthakuna Thirainda, D: Larry Lee Grismer, E & F: May Thu Chit.

FIGURE 5. Distribution ranges of the species of the complex of Trimeresurus albolabris. Notes: numbers indicate different localities where the species have been recorded (see Appendix V for the details of localities).