Trimeresurus cryptographicus Pawangkhanant, Idiiatullina, Nguyen, Ruangsuwan, Matsukoji, David, Suwannapoom & Poyarkov, 2025, sp. nov.

Trimeresurus cryptographicus sp. nov. urn:lsid:zoobank.org:act: 7EA37680-7455-47F8-8D9F-D6C6D3DB0885 (Figs. 2–3, 4B, 5A, 6, 7A; Tables 1, 2) Chresonyms: Cryptelytrops albolabris (non Trimeresurus albolabris Gray)—Chan-ard et al. (2015: in part). Trimeresurus macrops (non Trimeresurus macrops Kramer)— Poyarkov et al. (2023: 391, in part); Idiiatullina et al. (2024c: 377, in part). Holotype. ZMMU Re-17934, adult female, from Tham Kang Kao Cave, Ban Mung Subdistrict, Noen Maprang District, Phitsanulok Province, Thailand (16°34'00"N, 100°41'32"E; ca. altitude 100 m a.s.l.) collected by P. Pawangkhanant on 15 December 2020. Paratypes (n=6). RIM-00056, adult male, collected on 25 November 2021 by P. Pawangkhanant; RIM-00055, adult female, collected on 18 February 2024 by P. Pawangkhanant; RIM-00106, adult male, collected on 18 March 2020 by P. Pawangkhanant; ZMMU Re-18001–03, three subadult females, collected on 14 July 2024 by P. Pawangkhanant, S.S Idiiatullina, T. Ruangsuwan, T. Matsukoji, and N. A. Poyarkov, all paratypes were collected from the same locality as the holotype. Etymology. The species name “ cryptographicus ” is a Latin adjective in the nominative singular, masculine gender, derived from the classical Greek adjective kryptos (κρυπτός), “ cryptos ”, meaning “hidden”, and from the past participle of the verb graphein (γράφΕΙΝ), meaning “to write” or “to draw”. We coined this Greek word, in Latinized form, by allusion to the strong dorsal pattern present in juvenile specimens, which disappears and becomes barely visible in adult individuals like some cryptography text. Furthermore, this pitviper is a good example of cryptic and elusive species itself. We suggest the following common names for the new species: “ Ngu Khiew Hang Mai Ta To Si Jang ” (งูเขียวหางไหม้ตาโตสีจาง, in Thai), “ Cryptic Green Pitviper ” (in English), and “ Kripticheskaya bambukovaya kufiya ” (КриптическаЯ бамбуковаЯ куфиЯ, in Russian). Diagnosis. The new species is assigned to the subgenus Trimeresurus based on the following morphological attributes: a long calyculate hemipenis and a partially fused first supralabial and nasal scales (Malhotra & Thorpe 2004 [as Cryptelytrops]; David et al. 2011). The new species Trimeresurus cryptographicus sp. nov. differs from other members of the subgenus Trimeresurus by the combination of the following morphological characters: small size, maximum known SVL of 523 mm; dorsal scales in 23(22)-21-15 rows, moderately keeled except the outermost rows; ventral scales 171–178; subcaudal scales 57–73 (sexes pooled), all paired; iris golden yellow in both sexes; body uniformly bright grass-green with indistinct serrated dark transverse markings in adults (SVL 499–523 mm), but neonates and juveniles (SVL 231–245 mm) have prominent irregular serrated darkgrey crossbands on a light green dorsum; suborbital stripe bluish-white and thin in male, absent in females; ventrolateral stripe white, distinct, present on the first few dorsal scale rows in both sexes; throat, chin, and lower labials pale blue; ventral surfaces greenish-yellow; tail light brick-red mottled with dark spots above, and with white markings below. Description of the holotype. Adult female (Fig. 3), specimen in a good state of preservation. Body cylindrical, long, and thin (SVL 499 mm, TaL 99 mm, TL 598 mm; TaL/TL ratio 0.166) (Fig. 3A, B). Head triangular in dorsal view (Fig. 3C), elongate, clearly distinct from the neck (HL 27.5 mm, HW 16.3 mm; HW/HL ratio 0.59). Snout elongate, flattened, and rounded in dorsal view (Fig. 3C), rather rectangular in lateral view (Fig. 3E), with a very distinct and sharp canthus rostralis. Eyes large (ED 3.2 mm, EN 4.0 mm; ED/EN ratio 0.80). Rostral slightly visible in dorsal aspect, triangular (Fig. 3C). Pupil vertically elliptical, loreal pit present, triangular in shape (Fig. 3E, F). Nostril completely enclosed in the nasal scale; nasal scale partially fused with first supralabial (Fig. 3E, F). Shield bordering the anterior edge of the loreal pit fused with second supralabial, which is tall. Subocular long, thin, crescent-like, separated from the 4 th and 5 th supralabials by one row of scales and separated from the 6 th supralabial by 2/2 scales (Fig. 3E, F). Three preoculars on each side of the head; two upper preoculars located above the loreal pit, elongate, in contact with the single loreal, which separates them from the nasal; lower preocular forming the lower margin of the loreal pit, lower preocular in contact with third supralabial (Fig. 3E, F). A small scale between nasal and second supralabial; 2/2 postoculars; 10/10 supralabials, third the largest (Fig. 3E, F); 11/11 infralabials, those of the first pair in contact with each other behind the mental; the first two pairs of infralabials in contact with the single pair of chin shields (Fig. 3D–F). Six pairs of gulars aligned between the chin shields and the first preventral (Fig. 3D). One large pair of enlarged internasals, in contact; one supraocular, large (Fig. 3C). Scales on snout and in the interorbital region smooth, irregular, subimbricate; temporal and occipital scales feebly keeled (Fig. 3E, F). Dorsal scales in 23-21-15 rows, moderately keeled, except the first row, which is smooth (Fig. 3A, B). Two preventrals and 171 ventrals. Cloacal plate single; 57 subcaudals, all divided. Coloration. In life (Fig. 4B), the body is uniformly bright grass-green above and on the sides with a white ventrolateral stripe on the 1 st dorsal scale row. Interstitial skin darkgrey forming indistinct serrated dark transverse markings approximately every two to three scales. Tail light brick-red, dorsally the red coloration extending as far as the vent level, laterally with faint margins, mottled with dark brown to black on the end of tail; either side of the tail with distinct white markings each approximately one scale in width. Ventral surfaces of the body uniformly light yellowish-green. The dorsal surface of the head and the temporal region grassgreen lacking a postocular or subocular streak; supralabials, infralabials, chin and throat regions are light bluish-green. Iris golden yellow. In preservative (Fig. 3), after two years of storage in ethanol, the background dorsal color faded to grayish-blue; ventral background color faded to light yellowish-grey, getting a bluish-grey tinge posteriorly. Futhermore, dorsal markings became more distinct than in life and are well-discernible as regular transverse serrated dark-grey markings in the anterior part of the dorsum, getting less discernible posteriorly (Fig. 3A). Hemipenis. The right hemipenis examined on specimen RIM-00106 (male paratype; Fig. 5A) is a deeply forked, long, and slender structure. The bifurcation occurs at the level of the fourth subcaudal scale, and the hemipenis extends to the level of at least the eighth subcaudal scale, although it is difficult to determine its true length since it is not fully everted. At the base of each lobe immediately following the bifurcation are a series of enlarged soft spines. The hemipenis is calyculate distally; the calyces are ornamented with spines of various sizes. Variation. The main meristic and morphometric characters of the type series of Trimeresurus cryptographicus sp. nov. are summarized in Table 1; color variation of the type series is presented in Figures 4B and 6. All members of the type series are similar to the holotype, having a nasal scale partially fused with the first supralabial. The longest known specimen is 602 mm long (SVL 523 mm, TaL 79 mm; female, RIM-00055); the longest known male is 583 mm long (SVL 509 mm, TaL 74 mm; RIM-00056). Ratio TaL/TL 0.13–0.17 (adult males: 0.13, n=2; adult females: 0.13–0.17, n =2; subadult females: 0.13–0.16, n =3)) Body scalation. 23(22)-21-15 DSR; 171–178 VEN (without sexual dimorphism), 57–74 SC (adult males 71–73, n =2; adult females 57–64, n =2; subadult females 57–59, n =3). Head scalation. Internasals in contact with each other in all known specimens except for ZMMU Re-18002 (one small scale is present between internasals); SL 10–11; IL 10–12. Main characters of the pattern. In males the subocular streak is prominent, bluish-white, passing below the eye and fading out on lower preocular in the front while extending to ventrolateral stripe posteriorly; in females, the subocular streak is absent (Fig. 4B, 6F). Ventrolateral stripe present in both sexes on 1 st DSR, white. Iris golden yellow in both sexes. In newborn specimens the background color of the dorsum light green, with ca. 60 irregular serrated dark-grey crossbands (Fig. 6A, B). These dark bands cover about two dorsal scales in length mediodorsally, getting narrower on the lower flanks where they comprise about one dorsal scale. At the level of the vertebral row, the dark-grey transverse bands are separated by generally one lightgreen dorsal scale.According to our observations, the newborn serrated coloration (Fig. 6A, B) pertains for ca. 1–2 months, as in approximately 2–3 month old juveniles, it already fades significantly (Fig. 6C, D). In captivity, dorsum color may change to olive-green. Comparisons. The new species is phylogenetically placed within the subgenus Trimeresurus (Malhotra & Thorpe 2004 [as Cryptelytrops]; David et al. 2011) and is morphologically most similar to other green pitviper species from the T. macrops species complex, which includes T. cardamomensis, T. cyanolabris, T. macrops, and T. rubeus) as well as T. kanburiensis species complex (including: T. ciliaris, T. erythrochloris, T. honsonensis, T. kraensis, T. kanburiensis, T. kuiburi, and T. venustus); therefore, the comparisons with these eleven species appear to be the most pertinent. The main diagnostic characters separating Trimeresurus cryptographicus sp. nov. from these eleven species are summarized in Table 2 and Fig. 7. Trimeresurus cryptographicus sp. nov. (Fig. 7A) is distinguished from T. cardamomensis (Fig. 7B) by having: lower ratio TaL/TL in males (