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

Trimeresurus cryptographicus sp. nov.

urn:lsid:zoobank.org:act:7EA37680-7455-47F8-8D9F-D6C6D3DB0885

( Figs. 2–3 View FIGURE 2 View FIGURE 3 , 4B View FIGURE 4 , 5A View FIGURE 5 , 6 View FIGURE 6 , 7A View FIGURE 7 ; Tables 1, 2)

Chresonyms:

Cryptelytrops albolabris (non Trimeresurus albolabris Gray )—Chan-ard et al. (2015: in part).

Trimeresurus macrops View in CoL (non Trimeresurus macrops Kramer View in CoL )— 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. GoogleMaps

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 GoogleMaps .

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 View FIGURE 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 View FIGURE 3 ). Head triangular in dorsal view ( Fig. 3C View FIGURE 3 ), 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 View FIGURE 3 ), rather rectangular in lateral view ( Fig. 3E View FIGURE 3 ), 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 View FIGURE 3 ). Pupil vertically elliptical, loreal pit present, triangular in shape ( Fig. 3E, F View FIGURE 3 ). Nostril completely enclosed in the nasal scale; nasal scale partially fused with first supralabial ( Fig. 3E, F View FIGURE 3 ). 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 View FIGURE 3 ). 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 View FIGURE 3 ). A small scale between nasal and second supralabial; 2/2 postoculars; 10/10 supralabials, third the largest ( Fig. 3E, F View FIGURE 3 ); 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 View FIGURE 3 ). Six pairs of gulars aligned between the chin shields and the first preventral ( Fig. 3D View FIGURE 3 ). One large pair of enlarged internasals, in contact; one supraocular, large ( Fig. 3C View FIGURE 3 ). Scales on snout and in the interorbital region smooth, irregular, subimbricate; temporal and occipital scales feebly keeled ( Fig. 3E, F View FIGURE 3 ). Dorsal scales in 23-21-15 rows, moderately keeled, except the first row, which is smooth ( Fig. 3A, B View FIGURE 3 ). Two preventrals and 171 ventrals. Cloacal plate single; 57 subcaudals, all divided.

Coloration. In life ( Fig. 4B View FIGURE 4 ), 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 View FIGURE 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 View FIGURE 3 ).

Hemipenis. The right hemipenis examined on specimen RIM-00106 (male paratype; Fig. 5A View FIGURE 5 ) 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 View FIGURE 4 and 6 View FIGURE 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 View FIGURE 4 , 6F View FIGURE 6 ). 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 View FIGURE 6 ). 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 View FIGURE 6 ) pertains for ca. 1–2 months, as in approximately 2–3 month old juveniles, it already fades significantly ( Fig. 6C, D View FIGURE 6 ). 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 View FIGURE 7 .

Trimeresurus cryptographicus sp. nov. ( Fig. 7A View FIGURE 7 ) is distinguished from T. cardamomensis ( Fig. 7B View FIGURE 7 ) by having: lower ratio TaL/TL in males (0.13 vs. 0.17–0.20); dorsum pattern (grass-green with serrated dark transverse markings vs. uniformly bluish green, grass green or yellow-green); tail colour and pattern (light brick-red mottled with dark spots; ventral side of the tail with white markings vs. solid brick-red, approximately one-third (male) to half (female) distance to the vent on ventral surface).

Trimeresurus cryptographicus sp. nov. ( Fig. 7A View FIGURE 7 ) is distinguished from T. ciliaris ( Fig. 7G View FIGURE 7 ) by having: lower ratio TaL/TL in males (0.13 vs. 0.17); higher number SC in both sexes (71–73 in males, 57–64 in females vs. 59–63 in males, 52 in female); higher number of midbody scale rows (MSR 21 vs. 17); dorsum colour and pattern (grass-green with serrated dark transverse markings vs. emerald-green with reddish brown bands); present subocular streak in males (vs. absent); present ventrolateral body stripe (vs. absent); ventral colour (greenish-yellow vs. creamy white); iris colour (golden yellow vs. olive-green with faded brown horizontal stripe); tail colour and pattern (light brick-red mottled with dark spots; either side of the tail with white markings vs. dark brown mottled with rusty).

Trimeresurus cryptographicus sp. nov. ( Fig. 7A View FIGURE 7 ) is distinguished from T. cyanolabris ( Fig. 7C View FIGURE 7 ) by having: lower ratio TaL/TL in males (0.13 vs. 0.18–0.21); present subocular streak in males (vs. absent); dorsum pattern (grass-green with serrated dark transverse markings vs. uniformly bluish-green, grass green or yellowish-green); ventral colour (greenish-yellow vs. greenish-blue).

Trimeresurus cryptographicus sp. nov. ( Fig. 7A View FIGURE 7 ) is distinguished from T. erythrochloris ( Fig. 7D View FIGURE 7 ) by having: lower ratio TaL/TL in males (0.13 vs. 0.21); higher number of VEN in males (172 vs. 164); higher number of SC in males (71–72 vs. 67) and females (57–64 vs. 54); dorsum colour and pattern (grass-green with serrated dark transverse markings vs. grass-green with reddish-brown bands); ventrolateral body colour (white vs. red and white); ventral colour (greenish-yellow vs. pale creamish-green); tail colour and pattern (light brick-red mottled with dark spots; either side of the tail with white markings vs. brown with dark purplish-brown crossbars).

Trimeresurus cryptographicus sp. nov. ( Fig. 7A View FIGURE 7 ) is distinguished from T. honsonensis ( Fig. 7H View FIGURE 7 ) by having: lower ratio TaL/TL in males (0.13 vs. 0.23); lower number VEN in both sexes (172 in males, 171–178 in females vs. 186 in male, 183–186 in females); dorsum colour and pattern (grass-green with serrated dark transverse markings vs. straw-yellow with zig-zagged, irregular, darkbrown bands); present subocular streak in males (vs. absent); present ventrolateral body stripe (vs. absent); ventral colour (greenish-yellow vs. dull-white anteriorly becoming progressively darker posteriorly); iris colour (golden yellow vs. orange centrally and brown peripherally); tail colour and pattern (light brick-red mottled with dark spots; either side of the tail with white markings vs. slightly orangecolored hue with irregular dark bands).

Trimeresurus cryptographicus sp. nov. ( Fig. 7A View FIGURE 7 ) is distinguished from T. kanburiensis ( Fig. 7I View FIGURE 7 ) by having: lower ratio TaL/TL in males (0.13 vs. 0.17); higher number SC in both sexes (71–73 in males, 57–64 in females vs. 59 in male, 46–51 in females); higher number of midbody scale rows (MSR 21 vs. 19); dorsum colour and pattern (grass-green with serrated dark transverse markings vs. olive-gray with dark olive-brown bands); present subocular streak in males (vs. absent); present ventrolateral body stripe (vs. absent); ventral colour (greenish-yellow vs. creamy white); iris colour (golden yellow vs. brown, slightly golden); tail colour and pattern (light brick-red mottled with dark spots; either side of the tail with white markings vs. brownish-gray with olive-brown blotches).

Trimeresurus cryptographicus sp. nov. ( Fig. 7A View FIGURE 7 ) is distinguished from T. kraensis ( Fig. 7J View FIGURE 7 ) by having: lower ratio TaL/TL in males (0.13 vs. 0.17); higher number VEN in both sexes (172 in males, 171–178 in females vs. 167 in male, 169–171 in females); higher number SC in both sexes (71–73 in males, 57–64 in females vs. 62 in male, 52–54 in females); dorsum colour and pattern (grass-green with serrated dark transverse markings vs. dark bottle green with red orpurple bands); present subocular streak in males (vs. absent); ventral colour (greenish yellow vs. pale creamish-green); iris colour (golden yellow vs. slightly copper); tail colour and pattern (light brick-red mottled with dark spots; either side of the tail with white markings vs. brown with dark purplish-brown crossbars).

Trimeresurus cryptographicus sp. nov. ( Fig. 7A View FIGURE 7 ) is distinguished from its sister species T. kuiburi ( Fig. 7K View FIGURE 7 ) by having: lower ratio TaL/TL in males (0.13 vs. 0.17–0.19); higher number of midbody scale rows (MSR 21 vs. 19); slightly higher number of VEN in both sexes (172 in males, 171–178 in females vs. 164–166 in males, 164–171 in females); higher number of SC in both sexes (71–73 in males, 57–64 in females vs. 63–65 in males, 51–53 in females); dorsum colour and pattern (grass-green with serrated dark transverse markings vs. bottle green with red or purple bands); present ventrolateral body stripe (vs. absent); ventral colour (greenish-yellow vs. pale green); iris colour (golden yellow vs. copper); tail colour and pattern (light brick-red mottled with dark spots; either side of the tail with white markings vs. red with some thin lighter bands). According to our photos and description ( Fig.7 View FIGURE 7 ), hemipenes of these two species look rather similar, but the hemipenis of T. kuiburi is shorter (bifurcation occurs at the level of the third subcaudal scale and the hemipenes extend to the level of approximately the sixth subcaudal scale). Additional photos and measurements are needed to fully resolve this issue.

Trimeresurus cryptographicus sp. nov. ( Fig. 7A View FIGURE 7 ) is distinguished from T. rubeus ( Fig. 7F View FIGURE 7 ) by having; lower ratio TaL/TL in males (0.13 vs. 0.21–0.22); slightly higher number VEN in both sexes (172 in males, 171–178 in females vs. 164–171 in males, 158–163 in females); lower number SC in males (71–73 vs. 78–80); dorsum pattern (grass-green with serrated dark transverse markings vs. uniformly bluish green, grass green or yellow-green); iris colour (golden yellow vs. bright or deep reddish-orange).

Trimeresurus cryptographicus sp. nov. ( Fig. 7A View FIGURE 7 ) is distinguished from T. venustus ( Fig. 7L View FIGURE 7 ) by having: lower ratio TaL/TL in males (0.13 vs. 0.16–0.19); slightly higher number SC in females (57–74 vs. 51–57); higher number of midbody scale rows (MSR 21 vs. 19); dorsum colour and pattern (grass-green with serrated dark transverse markings vs. dark or bottle green with red or purple bands); present ventrolateral body stripe (vs. absent); ventral colour (greenish-yellow vs. pale green); iris colour (golden yellow vs. yellowish-brown/gold); tail colour and pattern (light brick-red mottled with dark spots; either side of the tail with white markings vs. brown with dark purplish-brown crossbars).

Though the new species was not recorded in sympatry with any other species of Trimeresurus , the possibility of its co-occurrence with the superficially similar T. macrops can not be excluded (see Fig. 1 View FIGURE 1 ). In particular, Trimeresurus cryptographicus sp. nov. ( Fig. 7A View FIGURE 7 ) is distinguished from T. macrops ( Fig. 7E View FIGURE 7 ) by having: notably lower ratio TaL/TL in males (0.13 vs. 0.17–0.22); dorsum pattern (grass-green with serrated dark transverse markings vs. uniformly bluish-green, grass green or yellowish-green); tail pattern (light brick-red mottled with dark spots; either side of the tail with white markings vs. dull brick-red, dorsally extending as far as vent, with clear margin on lateral side of tail); neonates and juveniles having a banded black and green pattern (vs. neonates and juveniles have the similar dorsal coloration as the adults, i.e. uniformly bluish-green, grass green or yellowish-green lacking dark markings).

Among the other species in the subgenus Trimeresurus , the new species can be readily distinguished from: T. fasciatus (Boulenger) , T. labialis Fitzinger in Steindachner, T. mutabilis Stoliczka (grass-green with serrated dark transverse markings vs. reddish-brown or purple or dark olive-brown bands on greyish-olive background). Trimeresurus cryptographicus sp. nov. can be distinguished from Trimeresurus andersoni Theobald , T. ayeyarwadyensis , T. cantori (Blyth) , T. erythrurus , and T. purpureomaculatus (Gray) by lower number of midbody dorsal scale rows (21 vs. 23–25 in T. andersoni and T. ayeyarwadyensis , 25–29 in T. cantori , 23 (rarely 24, 25) in T. erythrurus , 25 (rarely 27, 29) in T. purpureomaculatus ). The new species can be distinguished from: T. caudornatus Chen, Ding, Vogel & Shi , T. davidi Chandramouli, Campbell & Vogel , T. guoi , T. insularis Kramer , T. salazar Mirza, Bhosale, Phansalkar, Sawant, Gowande & Patel , T. septentrionalis Kramer , T. uetzi Vogel, Nguyen & David by having: throat, chin and lower labials in shades of blue (vs. creamy or white); relatively larger size of the eye (most obvious in adults), the relatively wider supraoculars, the shape of the head (widens quite abruptly behind the eyes vs. more elongate or oval) (see Vogel et al. 2023; Nguyen et al. 2024).

Distribution. Currently, Trimeresurus cryptographicus sp. nov. is known only from Tham Kang Kao Cave in Noen Maprang District, Phitsanulok Province, Phetchabun Mountain Range, Thailand (see Fig. 1 View FIGURE 1 ). The occurrence of the new species in karst formations in other provinces of northern or northeastern Thailand, such as Loei, Phetchabun, Chaiyapun, and Khon Kaen, is strongly anticipated. Based on the data obtained from our field surveys conducted in 2020, 2021, and 2024 at the type locality, no sympatric species of Trimeresurus were recorded in association with Trimeresurus cryptographicus sp. nov.

Natural history notes. Trimeresurus cryptographicus sp. nov. was recorded at relatively low elevations (ca. 100 m a.s.l.) in karst forest. The new species is semi-arboreal and nocturnal. All six specimens were found in the limestone karst near the cave entrance ( Fig. 4A View FIGURE 4 ). Other species of amphibians and reptiles at the same habitat in the type locality during the survey included: Microhyla cf. heymonsi Vogt , M. mukhlesuri Hasan, Islam, Kuramoto, Kurabayashi & Sumida , Micryletta cf. menglienica (Yang & Su) , Glyphoglossus molossus Günther , Polypedates megacephalus Hallowell , Theloderma vietnamense Poyarkov, Orlov, Moiseeva, Pawgkhanant, Ruangsuwan, Vassilieva, Galoyan, Nguyen & Gogoleva , Cyrtodactylus auribalteatus Sumontha, Panitvong & Deein , Gekko flavimaritus Rujirawan, Fong & Aowphol , Elaphe taeniura helferbergeri Schulz , and Indotestudo elongat a (Blyth). Nothing is known about its reproduction cycle.

Conservation status. To date, only seven specimens of the new species have been recorded in the type locality. Although we have conducted many surveys there since 2020–2024, it seems to be quite uncommon. The main threats to this species in type locality are habitat loss and degradation, and it can be subject to human destruction due to its venomous nature, often (mis)perceived to be dangerous to humans. Thus, we tentatively suggest that Trimeresurus cryptographicus sp. nov. to be considered “Data Deficient (DD)” following the IUCN Red List categories (IUCN Standards and Petitions Committee 2019).