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Article

Revalidation of the Arboreal Asian Snake Genera Gonyophis Boulenger, 1891; Rhynchophis Mocquard, 1897; and Rhadinophis Vogt, 1922, with Description of a New Genus and Tribe (Squamata: Serpentes: Colubridae) †

by
Van Wallach
1,*,
Rune Midtgaard
2 and
Emma Hsiao
3
1
Independent Researcher, 4 Potter Park, Cambridge, MA 02138, USA
2
Independent Researcher, Birke Alle 19, 1.18, 5500 Middelfart, Denmark
3
Independent Researcher, 161 Winter St., Weston, MA 02493, USA
*
Author to whom correspondence should be addressed.
†
urn:lsid:zoobank.org:pub:46332D99-41D4-4A87-911C-627BB90D09B6.
Diversity 2024, 16(9), 576; https://doi.org/10.3390/d16090576
Submission received: 26 July 2024 / Revised: 26 August 2024 / Accepted: 30 August 2024 / Published: 13 September 2024
(This article belongs to the Collection Feature Papers in Animal Diversity)
Browse Figures
Versions Notes

Abstract

:
Based on the latest molecular phylogenies of Gonyosoma sensu lato, which recovered five clades with robust support, we utilize morphological characters to demonstrate the distinctiveness of each clade, resulting in the resurrection of three genera (Gonyophis Boulenger, 1891; Rhynchophis Mocquard, 1897; and Rhadinophis Vogt, 1922) and a proposal of a new genus and a new tribe. A synopsis of the group, with descriptions and diagnoses, is provided for the five genera and eight species in addition to distribution maps and illustrations of the head of each taxon. An artificial key to the species and genera in the new tribe is presented in addition to the estimated origin times for each clade.

1. Introduction

There is a group of eight large tropical and subtropical colubrid forest snakes, mainly green in color, having elongated and compressed bodies that are typically arboreal in habitat and diurnal in activity. Their diet consists of small mammals (rats, squirrels, and bats); birds and their eggs in adults; and lizards, frogs, fish, and crickets in juveniles. Reproductively, they are oviparous, laying from 2 to 17 eggs in 1–4 clutches per year [1]. Their distribution encompasses Southeast Asia (including Bhutan, northeast India, southern China, and Taiwan), the Andamans and the Philippines, and Sundaland or western Indonesia [2]. Presently they are all lumped together under the genus Gonyosoma. They share a number of morphological traits while differing in other characteristics.
Günther’s [3] concept of Gonyosoma contained three species (oxycephalum, frenatum, and gramineus [=prasinum]), which was followed by Pope [4]. However, Boulenger [5] earlier on lumped many genera, including Gonyosoma, into his expanded concept of Elaphe. Dowling [6] was the first to recognize Gonyosoma oxycephalum as a separate taxon from the genus Elaphe, although the other species of arboreal Asian ratsnakes related to Gonyosoma have continued to be treated as members of Elaphe [1,7,8].
The consolidation of Gonyosoma began when Chen et al. [9] combined the following five species into Gonyosoma based upon one mitochondrial (cyt-b) and five nuclear genes (c-mos, RAG-1, SPTBN1, VIM4, and VIM5): G. boulengeri [10], G. frenatum [11], G. margaritatum [12], G. oxycephalum [13], and G. prasinum [14]. The species G. jansenii [15], for which molecular data were unavailable, was included in Gonyosoma based on its similarity to G. oxycephalum. Their phylogeny utilized both maximum likelihood and Bayesian inference methods, and the time calibration indicated that the group of species originated in the Early Miocene approximately 20.5 million years ago (MYA) with the separation of G. oxycephalum from wolfsnakes of the genus Lycodon (=38.1 MYA, Eocene fide Burbrink and Lawson [16]). The division between the two pairs of sister taxa, G. margaritatum plus G. prasinum and G. boulengeri plus G. frenatum, occurred ca. 15.8 MYA (=25 MYA, Late Oligocene fide Burbrink and Lawson [16]). The sister taxa G. margaritatum and G. prasinum diverged ca. 11.3 MYA with G. boulengeri and G. frenatum and then separated ca. 7.4 MYA [9].
Chen et al. [1] pointed out the three possible taxonomic solutions: (1) consolidate all species into one genus, Gonyosoma, retaining monophyly but losing taxonomic information; (2) retain Gonyosoma and consolidate the remaining species in Gonyophis, also retaining monophyly but with only two genera; and (3) retain the genera Gonyosoma, Gonyophis, Rhynchophis, and resurrect Rhadinophis for R. prasinus. Chen et al. [9] selected Solution 1, which involved synonymizing the genera Gonyophis, Rhynchophis, and Rhadinophis. They did so by remarking that Solution 3 would “provide little evidence for defining the evolutionary history of the related group” and that “other genera of similar age (~20 MYA) often have higher numbers of extant species.” We disagree and believe Solution 3 provides not only five clades but best elucidates the evolutionary history of the group. There are numerous colubrid genera that have a similar or fewer number of species that have evolved within the past 20 million years. These include, among others, the Elaphe quatourlineata species group (4 spp., 5.1 Mya, Jablonski et al. [17]); the Rhabdophis nuchalis species group (7 spp., 6.2 Mya, Zhu et al. [18]); Coronella (2 sp., 10 Mya, Stratakis et al. [19]); Zamenis (5 spp., 11.4 Mya, Salvi et al. [20]); Cerberus (5 spp., 14 Mya, Alfaro et al. [21]); Haldea, Liodytes, Regina, Storeria, and Virginia (1–5 spp. each, 11–14 Mya, McVay et al. [22]); Nerodia (10 spp., 15 Mya, McVay et al. [22]); Enhydris (6 spp., 16 Mya, Alfaro et al. [21]); Natrix (3 spp., 18 Mya, Guicking et al. [23]); Crotaphopeltis (5 spp., 21 Mya, Engelbrecht et al. [24]); and Spalerosophis (6 spp., 22 Mya, Yadollahvandmiandoab et al. [25]).
The low number of tissue samples led to the five tested species belonging to a single clade. Over the past decade, more specimens and tissue samples have become available, and the most recent phylogenies demonstrate that the currently recognized eight species (including the two newly described forms from China, G. coeruleum, Liu et al., [26], and G. hainanense, Peng et al., [27]) segregate into five well-supported clades [26,27,28]. Since these snakes also exhibit distinct morphological differences, we propose to resurrect three genera that were previously synonymized with Gonyosoma (Gonyophis Boulenger [29], Rhynchophis Mocquard [10], and Rhadinophis [30]) in addition to proposing a new genus for two species and establishing a new tribe for the group. We believe that by lumping all eight species into a single genus, taxonomic and phylogenetic information is lost. We prefer to follow the three rules of nomenclature (e.g., the Taxon-naming Criteria or TNC), namely monophyly, Clade Stability, and Phenotypic Diagnosability (Vences et al. [31]), and all three criteria are met herein.
The purpose of this paper is to provide a synopsis of each genus and species, including the new tribe and a key to the included taxa, supplemented with head figures and range maps, and highlight the distinctive diagnostic features of each rather than produce an exhaustive work on each taxon, for which numerous other references are available.

2. Materials and Methods

Due to the general dearth of basic systematic data, both morphological and phenotypic, in publications dealing with molecular systematics, we present such data herein for each species and genus. We collected standard external morphological data for each species based on examinations of specimens and a review of the primary and secondary literature. All measurements were made to the nearest mm, including the LOA (overall length), SVL (snout–vent length), and TL (tail length). The relative tail length (RTL) = TL/LOA. In addition, distribution by elevation and some natural history features were noted. Characters of scutellation include dorsal scale rows (ASR = anterior rows one head length behind the head, MSR = midbody, and PSR = posterior rows one head length in front of the vent), carination (S = entirely smooth and k + s = partly keeled and partly smooth), K.R. = keeled scale rows, paired apical scale pits, number of ventrals, cloacal shield (E = entire or undivided and D = divided), number of subcaudals, condition of the nasal shield (E = entire or undivided, S = semidivided, and D = divided), loreal shield (present or absent and shape), number of supralabials and which ones enter the orbit, number of pre- and postoculars, number of anterior and posterior temporals, number of infralabials and which ones contact the anterior genials, minimum and maximum reported total length in mm, and coloration of body parts (including the iris, mouth, and tongue). A forward slash separates the occurrence of two different conditions, and data presented parenthetically indicate a rare occurrence. The position of the umbilicus in snakes can be determined (even in some adults) by a fine and light median line covering 3–4 scales and/or faint notches along the midline of said scales. The distance from the anteriormost scale to the vent represents the umbilicus–vent interval, and it is calculated as a percentage of the total number of ventrals.
We were unable to obtain a specimen of G. hainanensis and relied on a recent description of this species [26], although it is lacking in some respects. There is considerable variation and discrepancy in some characters of this group, so we attempted to sort out the conflicting data. For descriptions of coloration characters, in addition to the literature, we studied photos on the Internet when positive identifications were confirmed. The most comprehensive treatment of Gonyosoma is by David et al. [32], who covered four of the eight species (G. coeruleum, G. frenatum, G. oxycephalum, and G. prasinum).
The material examined was from the following institutions: FMNH (Field Museum of Natural History, Chicago, IL, USA), ROM (Royal Ontario Museum, Toronto, ON, Canada), SDSU (Biology Department, San Diego State University, San Diego, CA, USA), and UCM (University of Colorado Museum of Natural History, Boulder, CO, USA). The new genus and tribe names are registered with ZooBank (LSID urn:lsid:zoobank.org:pub:A3F885F0-E466-4EF8-8E8C-639168E011AF).

3. Results

The species forming this group are in general rare in collections, with the one exception being Gonyosoma oxycephalum. Being mainly arboreal, they spend a significant part of their lives in trees, often up in the canopy, so they are not easily collected. We summarize the morphological and ecological data for each species (Table 1) and genus (Table 2) below.

3.1. Gonyophis

GONYOPHIS Boulenger, 1891 (Map 1).
Type species: Gonyosoma margaritatus Peters, 1871.
Content: monotypic.
Diagnosis: Gonyophis is separable from all other genera by its color and pattern, consisting of an orange or yellow head; multicolored dorsum; a black tail with orange, yellow, or red rings; anterior genials that are longer than posterior genials; and apical scale pits that are close together.

Gonyophis margaritatus 

Gonyophis margaritatus (Peters, 1871) (Figure 1).
Description [34,35,36,37,38]: Moderately large snakes with an average adult size of 1.0–1.5 m; overall size range of 424–1943 mm confirmed, but reported maximum length of 2.0 m [37]. Body elongated and laterally compressed in 19-19-15 longitudinal rows (rarely 21 rows anteriorly and 17 rows posteriorly). Dorsal scales moderately keeled along the middorsal 7–13 rows (i.e., vertebral row and adjacent 3–6 rows), most distinct anteriorly, faint at midbody, and absent posteriorly; lower 3 to 6 scale rows smooth. Elongated apical scale pits spaced closely together, distinctly present in nuchal region, faintly visible at midbody, and invisible posteriorly. Scale row reduction involving paravertebral rows. Ventrals 230–249, angulated with lateral keels and notches. Subcaudals 108–130, also angulated, keeled, and notched. Cloacal shield divided. Head distinct from neck, and eye moderate in size with round pupil and black or reddish-brown iris. Nasal shield elongated, divided, or semidivided with a dorsal suture. Preocular 1, postoculars 2, supralabials usually 9 (rarely 8 or 10) with 3 usually entering the orbit (4–6, less commonly 3–5 or 5–7), and rarely only 2 (5–6) entering orbit. Temporal formula varies from 2 + 2 + 2 to 2 + 3 + 3. Infralabials 10–12 with the first 5 contacting the anterior genials. Anterior genials longer than posterior genials. Tail long and slender, 22.6–33.3% of total length. A total of 20–23 aglyphous maxillary teeth. Umbilicus–vent interval moderate (11.8–13.3% of total ventrals). Head dorsum, lateral snout, and labials bright orange, and posterior head and temporal region black (including a broad postocular bar). Dorsum black, each scale with a central green, yellow, or blue dot, with the posterior body and tail encircled by 5–17 orange or yellow rings, oblique and diffuse at midbody but brighter and brick red, orange, or yellow on tail. Chin and venter yellow, orangish yellow, or orangish pink. Lateral edges of ventrals have irregular, alternating black marks. Subcaudals black, crossed with 5–8 orange/yellow/red rings. Mouth pink, and tongue light with black tips.
Natural history [16,36,38,39,40,41]: A rare diurnal, arboreal species inhabiting lowland and montane primary tropical rainforests, often in the forest canopy. An excellent and agile climber, able to scale vertical tree trunks with ease. Presumably, it feeds on small mammals, bats, and birds, but it is only known to feed on fish in captivity. Specimens have been captured in fish nets, so they may frequent habitats in the vicinity of water like G. jansenii and G. prasinus. Reproduction is unknown but is presumed to be oviparous; it lacks ontogenetic color change, with juveniles exhibiting the same pattern as adults. Although a rare species with a limited distribution that is nowhere common, it is listed by the IUCN as a Least Concern species and is not included in CITES Appendices. Its major threat is deforestation, but due to its beautiful coloration, it is popular in the pet trade and should be closely monitored. Its vernacular name is the rainbow tree snake or Royal tree snake.
Distribution (Figure 2): Indonesia (Kalimantan), East Malaysia (Sabah and Sarawak), and West Malaysia (Johor, Kelantan, Pahang, Perak, and Selangor), recorded from sea level to 1800 or 2000 m, but found mainly in lowland forests below 700 m [2]. Now extinct in Singapore.

3.2. Gonyosoma

GONYOSOMA Wagler, 1828 (Figure 3).
Type species: Coluber oxycephalus Boie, 1827.
Content: two species—Gonyosoma jansenii Bleeker, 1858 and G. oxycephalum (Boie, 1827).
Diagnosis: Gonyosoma is unique among the other genera in having 23–27 midbody scale rows with smooth scales throughout; a red, brown, or black tail; a blue tongue with black tips; an avascular, multichambered tracheal lung; and a relatively large left lung.
Distribution: Southeast Asia (from Myanmar and Vietnam southwards), Malay Archipelago, from 20 to 1400 m [2].

3.2.1. Gonyosoma jansenii

Gonyosoma jansenii Bleeker, 1858 (Figure 4).
Synonym: Allophis (Elaphis) nigricaudus Peters, 1872.
Diagnosis: Gonyosoma jansenii is separable from G. oxycephalum by its tail and subcaudal coloration (black vs. red, brown, or gray), anterior temporals (1 vs. 2), and internasal proportions (subequal length and width vs. length twice the width). The only unique characteristic of G. jansenii among the other four genera is the black color of the tail and subcaudals. See Lang and Vogel [40] for the most detailed description.
Description [1,36,42,43,44]: Large snakes with an average adult size of 1.5–2.0 m and overall size range of 120–2374 mm. Head distinct from neck. Body elongated and laterally compressed with oblique scale rows, 21–23 rows anteriorly, 23–25 midbody rows, and 15–17 (rarely 13) rows posteriorly. Dorsal scales entirely smooth. Apical scale pits elongated and paired, large and distinct throughout. Scale row reduction involving paravertebral rows. Ventrals 245–257, angulated with lateral keels. Subcaudals 130–140, angulated and keeled. Divided cloacal shield. Internasal length greater than width, frontal moderate in size with tapered sides, large preocular in contact with frontal, loreal elongated, twice as long as deep. Eye moderate in size with round pupil and yellow or orange iris. Nasal shield elongated, divided, or semidivided with a ventral suture. Preocular 1, postoculars 2, supralabials 9–10 with 5th to 7th entering orbit (rarely only 6th to 7th contacting eye). Anterior temporals 1 (rarely 2), middle temporals 2–3, posterior temporals 3, normally 1 + 2 + 3 or 1 + 3 + 3. Infralabials 11–13 with the 1st to 5th contacting the anterior pair of chin shields. Posterior genials longer than anterior pair. Tail long and slender, 22.8–31.0% of total length. Dentition unknown. Umbilicus–vent interval moderate (16.7% of total ventrals). No ontogenetic color change from juvenile to adult. Dorsal color variable. Head yellowish olive, gray, or black, lacking a distinct black pre- and postocular bar. Dorsum olive or yellowish brown, turning black posteriorly, with a narrow, discrete, ventrolateral stripe on posterior body, not continuing onto tail. Venter yellow to black. Tail black above and below. Mouth pink. Tongue blue with black tips.
Natural history [1,36,44,45,46]: Inhabits primary rainforests, both lowland and montane, in addition to disturbed areas and mangroves, often in association with rivers and domestic dwellings. Semiarboreal and diurnal, it is a shy but active hunter with a diet that includes birds and mammals. Reproduction is oviparous with 2–9 eggs in a clutch with up to four clutches per year, neonate size 420–560 mm. This species inflates its neck vertically in a defensive posture, made possible by its tracheal lung. A rarely encountered snake, it is listed by the IUCN as a Least Concern species and not included in CITES Appendices. Its vernacular name is the black-tailed ratsnake or Jansen’s racer.
Distribution (Figure 5): Indonesia (Sulawesi, incl. nearby islands Buton, Kabaena, and Selayar), from 50 to 1000 m [2].

3.2.2. Gonyosoma oxycephalum

Gonyosoma oxycephalum (Boie, 1827 [47]) (Figure 6).
Synonyms: Gonyosoma viride Wagler, 1828 [49]; Herpetodryas oxycephalus Schlegel, 1837 [50]; Alopecophis chalybeus Gray, 1849 [51]; Aepidea robusta Hallowell, 1861 [52]; Coluber deroyi Werner, 1923 [53]; Coluber floweri Werner, 1925 [54]; Coluber janseni elegans Werner, 1926 [55].
Diagnosis: Gonyosoma oxycephalum is distinguished from G. jansenii by its tail and subcaudal coloration (red, brown, or gray vs. black), anterior temporals (2 vs. 1), and internasal proportions (length twice the width vs. length and width subequal). Gonyosoma oxycephalum is unique among the other four genera in its anterior and midbody scale rows (23–27 vs. 19–21); dorsal scales (entirely smooth vs. partly keeled); a red, gray, or brown tail (vs. green); a multichambered tracheal lung (vs. absent); and a large left lung (vs. a tiny left lung).
Description [32,41,44,56,57,58,59,60,61]: Large snakes with an average adult size of 1.6–2.0 m and overall size range of 170–2400 mm. Head distinct from neck. Body elongated and laterally compressed with oblique scale rows: 23–27 rows anteriorly, 23–25 (rarely 27) midbody rows, and 15–17 rows posteriorly. Dorsal scales completely smooth. Large, elongated, faintly visible paired apical scale pits present throughout body. Scale row reduction involving paravertebral rows. Ventrals 229–263, angulated with lateral keels and notches. Angulated subcaudals 120–157. Cloacal shield divided by an oblique suture. Internasal length greater than width. Frontal moderate in size with tapered sides. Loreal elongated, twice as long as high. Large preocular in contact with frontal. Eye moderate in size with round pupil and blue, green, yellowish-green, or gray iris. Nasal shield elongated, divided, semidivided with a dorsal or ventral suture, or entire. Preocular 1, postoculars 2, supralabials usually 9–11 (rarely 7–8) with 3 (4th–6th, 5th–7th, and 6th–8th) normally entering the orbit, less commonly only 2 (4th-5th, 5th–6th, and 6th–7th). Anterior temporals two (rarely one or three), middle temporals two (rarely four or five), and posterior temporals three. Infralabials 12–15 with the first 5 (rarely 6 or 7) contacting the anterior genials. Posterior chin shields longer than anterior pair. Tail long and slender, 20.9–27.7% of total length. Maxillary teeth 20–25, palatine teeth 12, pterygoid teeth 13–15, and dentary teeth 24–26. Umbilicus–vent interval moderate (14.2–18.7% of total ventrals). Neonates are typically green, rarely reddish brown, normally retaining that color as adults with a red, brown, olive, or green head. Typically a dark green, light green, or yellowish-green body with or without a broad, distinct, yellow ventrolateral stripe consisting of the lateral edges of the ventrals (lateral to keels and notches), but dorsum color variable in some areas. Venter green, yellowish green, or yellow. Dorsal tail red, yellowish brown, or gray, usually lacking a ventrolateral stripe. Subcaudals light with a median dark zigzag stripe. A weak pre- and postocular streak may be present or absent, the latter bolder than the former. Mouth pink with a blue tongue with black tips. Dorsal coloration of some specimens may be variable with a gray or grayish-brown dorsum in Java, an orange dorsum in Sulawesi, or a yellow dorsum in Thailand and the Philippines. A multichambered tracheal lung with 15–20 air cells present, allowing the snakes to inflate their necks and produce sound. The vestigial left lung is large for colubroids (5.6–7.5% SVL).
Natural history [1,35,38,40,44,62,63,64,65,66,67]: Inhabits a variety of primary and secondary forest habitats from tropical humid evergreen forests to secondary and open forests, also including mangroves, marshes, riverbanks, and even disturbed areas and rural gardens. Preference for vegetation and branches near or overhanging fresh or brackish water. Activity is mainly diurnal but also crepuscular and nocturnal at times. Adults are strictly arboreal, except Javanese snakes, which are mainly terrestrial, with juveniles being more semiarboreal in nature. Diet consists mainly of birds and bats, the latter caught in flight near cave entrances, although bird eggs and arboreal mammals like tree rats and tree squirrels are also eaten; juveniles feed upon lizards and cave crickets. Reproduction is oviparous with mating occurring in the trees and 2–12 eggs in a clutch, 1–4 annual clutches, and neonates measuring 229–560 mm. As a defensive strategy, this snake will inflate its neck region ventrally, exposing the black interstitial skin beneath. This is assisted by the presence of its tracheal lung, which has numerous inflatable air sacs. According to the IUCN, it is a Least Concern species and is not included in CITES Appendices. Its vernacular name is the Red-tailed ratsnake or Red-tailed racer.
Distribution (Figure 7): Brunei, Cambodia, India (Andaman Islands), Indonesia (Bali, Bangka, Belitung, Java, Kalimantan, Karimata Islands, Legundi, Lombok, Natuna Islands, Nias, Panaitan, Riau Islands, Sebuku, and Sumatra), Laos, Malaysia (Sabah, Sarawak, and West Malaysia [incl. Langkawi Archipelago and Seribuat Archipelago (incl. Tioman)]), Myanmar, the Philippines (Babuyan Islands [Calayan and Camiguin Norte], Balabac, Batan Islands [Batan, Itbayat, and Sabtang], Bohol, Camiguin Sur, Dinagat, Dumaran, Lubang, Luzon, Mindanao, Mindoro, Negros, Palawan, Panay, Samar, Sibuyan, and Sulu Islands [Bongao]), Singapore, Thailand, and Vietnam, recorded from 20 to 1400 m [2].

3.3. Rhadinophis

RHADINOPHIS Vogt, 1922 (Figure 7).
Type species: Herpetodryas frenatus Gray 1853.
Content: monotypic.
Diagnosis: Rhadinophis is distinguished from the other four genera by the absence of a loreal shield (fused with prefrontal), eight supralabials, and a frontal that is narrow with parallel sides.

Rhadinophis frenatus 

Rhadinophis frenatus (Gray 1853) (Figure 8).
Synonyms: Rhadinophis melli Vogt, 1922 [30]; Gonyosoma caldwelli Schmidt, 1925 [69]; Chrysopelea ornata lungchuanensis Hu et al., 1958 [70].
Description [32,71,72,73]: Moderate-sized snakes with an average adult size of 0.75–1.0 m and overall size range of 120–1475 mm. Head distinct from neck. Body elongated and laterally compressed. Dorsal scale rows arranged in longitudinal rows in 19 (rarely 21)-19 (rarely 17)-15 (rarely 13 or 15) rows. Three middorsal scale rows (vertebral and paravertebral) feebly keeled, with lower eight rows smooth. Paired apical scale pits small and more rounded than elongated but indistinct at midbody and absent in nuchal and cloacal region. Scale row reduction involving paravertebral rows. Ventrals 198–235, angulated and notched. Subcaudals 108–149, angulated. Cloacal shield divided. Internasal length greater than width, frontal narrow with parallel borders. Nasal shield divided. Loreal absent, fused with prefrontal. Preocular not in contact with frontal. Eye moderate in size with round pupil and golden yellow iris. Preocular 1, postoculars 2, supralabials usually 8 (rarely 9) with 3 (3rd–5th or 4th–6th) entering the orbit. Temporal formula varies from 2 + 2 + 2 to 2 + 3 + 3 (rarely 1 or 3 anterior temporals and 4 posterior temporals). Infralabials 9–11 with the first 5 (rarely 6) contacting the anterior genials. Posterior genials longer than anterior genials. Tail long and slender, 22.0–32.5% of total length. Maxillary teeth 19–25, palatine teeth 10–13, pterygoid teeth 21, and dentary teeth 21–22. Umbilicus–vent interval moderate (14.1% of total ventrals). Ontogenetic color/pattern change from juveniles to adults with neonates being gray, brown, or olive with black crossbars and outlining of head shields. Adults green (head, body, and tail) with a broken ventrolateral light stripe broken up by dark triangles every 2–3 ventrals; tail also with a ventrolateral stripe, venter yellowish green to white, and subcaudals with a median zigzag line. Head with a weak-to-strong preocular and postocular bar. Mouth interior pink to purple.
Natural history [1,61,68,74,75,76]: Occurs in tropical and subtropical lowland and montane evergreen forests. A diurnal snake that is arboreal, semiarboreal, and terrestrial, it sometimes inhabits low brush and bamboo thickets, woodpiles, rock crevices, and agricultural areas. Diet consists of rodents, birds, and lizards, killed by constriction, with juveniles feeding on fish and tadpoles. The concave preocular region suggests that this snake has binocular vision. Reproduction is oviparous with 6–12 eggs in a clutch with hatchlings 120–150 in length. Although rare, it is listed by the IUCN as a Least Concern species and not included in CITES Appendices. Its vernacular name is the Assam Trinket snake or Khasi Hills ratsnake.
Distribution (Figure 9): Bhutan, China (Anhui, Chongqing, Fujian, Guangdong, Guangxi, Guizhou, Henan, Hubei, Hunan, Jiangxi, Shaanxi, Sichuan, Yunnan, and Zhejiang), India (Arunachal Pradesh, Assam, and Meghalaya), Laos, Taiwan, and Vietnam, from 170 to 2800 m. Presumably also in Myanmar [2].

3.4. Rhynchophis

RHYNCHOPHIS Mocquard, 1897 (Figure 10).
Type species: Rhynchophis boulengeri Mocquard, 1897.
Content: two species—Rhynchophis boulengeri Mocquard, 1897 and R. hainanensis (Peng et al., 2021).
Diagnosis: Rhynchophis is unique among the other four genera with a snout having a projecting rostral appendage of 6–10 small scales (vs. absent), frontal shape (subtriangular vs. not subtriangular), and genial proportion (posterior genials longer than anterior pair vs. otherwise).
Distribution: China (Guangxi and Hainan) and Vietnam (incl. Ha Long Bay Islands: Cat Ba Island), from sea level to 2000 m.

3.4.1. Rhynchophis boulengeri

Rhynchophis boulengeri (Mocquard, 1897) (Figure 11).
Synonym: Proboscidophis versicolor Fan, 1931 [79].
Diagnosis: Rhynchophis boulengeri is separable from R. hainanensis by the presence of a single loreal (vs. two) and a dark postocular bar. The only unique characteristics of R. boulengeri among the other four genera are the nasal appendage and a subtriangular frontal (shared with R. hainanensis).
Description [7,80,81,82]: Moderate-sized snakes with an average adult size of 0.8–1.0 m and overall size range of 170–1630 mm. Head distinct from neck. Body elongated and laterally compressed. Dorsal scale rows arranged longitudinally in 19 anterior rows, 19 (rarely 17 or 18) midbody rows, and 15 (rarely 13) posterior rows, with and without some keeling. Middorsal 3–7 rows with weakly keeled scales, with lower 6–8 rows entirely smooth. Elongated apical scale pits throughout, paired, large, and parallel in orientation but indistinct. Scale row reduction involving paravertebral rows. Ventrals 207–227, angulated, keeled, and notched. Subcaudals 101–133, angulated. Cloacal shield divided. Internasal length equal to internasal width and frontal subtriangular. Nasal shield divided or semidivided with a superior suture. Elongated loreal present. Eye moderate in size with round pupil and reddish-brown iris. In total, 1 large preocular in contact with frontal, postoculars 2, supralabials normally 9 (rarely 10) with 3 (4th–6th or 5th–7th) entering the orbit. Temporal formula varies from 2 + 2 + 3 to 2 + 3 + 3 (rarely one anterior temporal). Infralabials 10–11 with the first 5 (rarely 6) contacting the anterior genials. Posterior genials longer than anterior genials. Tail long and slender, 20.6–30.2% of total length. Maxillary teeth 16–22 and dentary teeth 25. Umbilicus–vent interval moderate (13.1–13.7% of total ventrals). Ontogenetic color/pattern change from juveniles to adults, with neonates being gray or brown with black markings. Adults green (head, body, and tail) with a narrow, distinct, ventrolateral light stripe that continues onto tail. Venter pale green. Subcaudals dark with a solid-green stripe. Head with a weak pre- and postocular stripe. Mouth interior pink. Tongue pink.
Natural history [39,44,83,84,85,86,87,88,89]: Inhabits the lower and middle layers of primary subtropical and tropical monsoon rainforests, particularly near streams and lakes, but can also be found in degraded forests. Captive specimens spend a lot of time in water, especially juveniles. Arboreal and semiarboreal in habits, it is both diurnal and nocturnal, with most activity during the first half of the night. Diet consists mostly of rodents and small mammals with juveniles preferring lizards and fish. Captive juveniles may be cannibalistic. Reproduction is oviparous with 2–17 eggs in an annual clutch, with the females often guarding the eggs after oviposition, and neonates measure 170–385 mm. Listed by the IUCN as a Least Concern species and not included in CITES Appendices. Its vernacular name is the rhinoceros ratsnake or Vietnamese horned snake.
Distribution (Figure 12): China (Guangxi) and Vietnam (incl. Ha Long Bay Islands: Cat Ba Island), documented from sea level to 2000 m [2].

3.4.2. Rhynchophis hainanensis

Rhynchophis hainanensis (Peng et al., 2021) (Figure 13).
Diagnosis: Rhynchophis hainanensis can be distinguished from R. boulengeri by the presence of two loreals (vs. one) and absence of a dark postocular bar (vs. present). It is unique among the other four genera in the presence of a nasal appendage and a subtriangular frontal (shared with R. boulengeri).
Description [27]: Moderate-sized snakes with an average adult size of 0.7–0.9 m and overall size range of 150–1229 mm. Head distinct from neck. Body elongated and laterally compressed. Dorsal scale rows arranged in longitudinal rows in 19-19-15 (rarely 13) rows, with and without some weak keeling. Apical scale pits unknown. Ventrals 216–221, angulated and keeled. Subcaudals 122–133, angulated and keeled. Cloacal shield divided. Internasal length equal to internasal width and frontal subtriangular. Nasal shield semidivided with a dorsal suture. Loreal divided into two shields. Eye moderate in size with round pupil and brown iris. One large preocular contacting frontal, two postoculars, supralabials nine with three, the fourth, fifth, and sixth, in contact with the eye. Temporal formula 2 + 2 + 3. Infralabials 10–12 with 1st to 5th in contact with the anterior chin shields. Posterior genials longer than anterior genials. Tail long and slender, 19.4–32.5% of total length. Dentition unknown. Neonates gray with ontogenetic variation that turns green in adults. Dorsal head, body, and tail green; venter and subcaudals green; and a yellow ventrolateral stripe present but not on tail. Lacking pre- and postocular dark streaks. Mouth interior and tongue unknown.
Natural history [27]: Little is known about this recently described species. Inhabits subtropical rainforests, particularly valleys with streams. Arboreal with nocturnal activity recorded (presumably also diurnal like R. boulengeri). Feeds on mice in captivity. Oviparous with six eggs per clutch. Its conservation status by the IUCN and CITES has not yet been evaluated. Its vernacular name is the Hainan rhinoceros ratsnake.
Distribution (Figure 14): China (Hainan). Currently known only from the Diaoluoshan Mountains (type locality) and the Jianfengling Mountains, from 80 to 900 m [2].

3.5. Verdigrophis gen. nov.

VERDIGROPHIS gen. nov. (Figure 15).
Type species: Coluber prasinus Blyth, 1855.
Content: two species—Verdigrophis coeruleus (Liu et al., 2021) and V. prasinus (Blyth, 1858).
Diagnosis: the only unique characteristic of Verdigrophis among the other four genera is the anterior and posterior genials subequal in length.
Etymology: The generic name is derived from the Latin verdigris, meaning bluish green, greenish blue, or shades between green and blue, in reference to the coloration of the dorsum and iris. Verdigris is also based on the Old French term vert-de-Grèce, which refers to the turquoise pigment resulting from the oxidation of copper.
Distribution: Southeast Asia (from Bhutan and S. China to West Malaysia), 75–2560 m [2].

3.5.1. Verdigrophis coeruleus Comb. nov.

Verdigrophis coeruleus (Liu et al., 2021) (Figure 16).
Diagnosis: The only unique characteristics of Verdigrophis coeruleus among the other genera are a blue iris and gray mouth interior. Verdigrophis coeruleus differs from V. prasinus by its ventrolateral stripe (white vs. yellow), cloacal shield (divided vs. entire), iris color (blue, greenish blue, or bluish green vs. greenish yellow or brownish yellow), tongue color (brownish yellow vs. reddish brown), and mouth interior (gray vs. pink).
Description [26,32]: Moderate-sized snakes with an average adult size of 0.8–1.0 m and overall size range of 220–1192 mm. Head distinct from neck. Body elongated and laterally compressed. Dorsal scale rows normally arranged in 19-19-15 longitudinal rows (rarely 20 anterior rows, 15 or 17 midbody rows, and 13 or 17 posterior rows). In total, 5–11 scale rows are feebly keeled, with lower 4–6 rows being smooth. Apical scale pits paired, large, and widely spaced anteriorly and at midbody but absent posteriorly. Scale row reduction involving paravertebral rows. Ventrals 181–224, angulated, keeled, and presumably notched. Subcaudals 88–128. Cloacal shield divided. Internasal width greater than length. Frontal broad with tapered sides. Nasal shield semidivided with a ventral suture. Loreal absent, fused with prefrontal. Preocular not in contact with frontal. Moderate-sized eye with round pupil and a blue or greenish-blue iris. Preocular 1, postoculars 2, supralabials usually 9 (rarely 8 or 10) with 3, the 3rd–5th, entering the orbit. Anterior temporals 1–2, middle temporals 2 (rarely 1 or 3), and posterior temporals 2–3. Infralabials 9–11 with the first 5 contacting the anterior genials. Both pairs of genials equal in length. Tail long and slender, 22.4–27.7% of total length. A total of 20–21 maxillary teeth. Umbilicus–vent interval unknown. Dorsum of head, body, and tail are green, bluish green, or blue, lacking a ventrolateral stripe on venter and subcaudals. Venter pale green to bluish green. Iris blue, greenish blue, or bluish green (juveniles with yellow iris). Interior of mouth gray. Tongue brownish yellow with black tips.
Natural history [27,28,32]: It inhabits a variety of primary and secondary rainforests, from tropical humid evergreen forests to subtropical deciduous montane forests. Preference for moist areas with big trees and tangled vegetation near rivers and streams but also bamboo thickets, shrubs, and bushes. An agile and swift species, diurnal and crepuscular, mainly arboreal and sleeping in the trees at night but occasionally can be found on the ground. Diet includes small mammals like rodents, which are constricted, and presumably also birds and lizards. Reproduction is oviparous with 3–11 eggs/clutch and neonates measuring 200–280 mm. Its conservation status by the IUCN and CITES has not yet been evaluated. Its vernacular name is the Blue ratsnake.
Distribution (Figure 17): China (Guangxi, Guizhou, Hainan, Sichuan, and Yunnan), Laos, Malaysia (West Malaysia), Myanmar, Thailand, and Vietnam, from 250 to 1650 m [2].

3.5.2. Verdigrophis prasinus Comb. nov.

Verdigrophis prasinus (Blyth, 1854) (Figure 18).
Synonym: Gonyosoma gramineum Günther, 1864.
Diagnosis: Verdigrophis prasinus is unique among the other four genera by its entire cloacal shield. It is distinguished from V. coeruleus by its iris color (yellowish green vs. blue), tongue color (reddish brown vs. brownish yellow), mouth interior (pink vs. gray), and the cloacal shield (entire vs. divided).
Description [32]: Moderate-sized snakes with an average adult size of 0.9–1.2 m and overall size range of 150–1355/1500 mm. Head distinct from neck. Body elongated and laterally compressed. Dorsal scale longitudinally arranged in 19-19-15 rows typically, but there are rarely 17 or 21 rows anteriorly (17 at midbody and 13, 14, or 17 rows posteriorly). A total of 7–9 midbody scale rows feebly keeled, with lowermost 5–6 rows smooth. Paired apical scale pits large, elongated, and widely spaced. Scale row reduction involving paravertebral rows. Ventrals 186–209, angulated, keeled, and notched. Subcaudals 91–116, angled, keeled, and notched. Cloacal shield entire. Internasal width greater than length, frontal broad with tapered sides. Nasal shield divided or semidivided with a ventral suture. Loreal single (rarely absent). Preocular not in contact with frontal. Moderate-sized eye with round pupil and a blue or greenish-yellow or olive iris. Preocular 1, postoculars 2, supralabials usually 9 (rarely 8) with 3, the 3rd–5th (rarely 4th–5th), entering the orbit. Anterior temporals 1–2 (rarely 3), middle temporals 1–2 (rarely 3), and posterior temporals 2 (rarely 3). Infralabials 9–10 (rarely 12) with the first 5–6 contacting the anterior genials. Both pairs of chin shields subequal in length. Tail long and slender, 19.4–26.7% of total length. Maxillary teeth 19–23 and dentary teeth 25. Umbilicus–vent interval 13.7–14.4% of total ventrals. Lacking ontogenetic color change: juveniles are green; head and body dorsum green, bluish green, or blue; tail green; venter pale greenish yellow, yellow, or white; subcaudals dark, lacking ventrolateral stripe on venter and subcaudals; and no pre- or postocular bar. Iris greenish yellow or brownish yellow. Mouth interior pink. Tongue reddish brown with black tips.
Natural history [1,28,36,44,61,74,90,91,92,93,94]: Inhabits tropical evergreen and broadleaf forests, both lowland and submontane, including deciduous montane forests. An arboreal species that is usually found in trees or foliage associated with bodies of water, such as bamboo clusters, bushes, and cane breaks. It is reported to be diurnal, crepuscular, and even nocturnal. Diet consists mainly of small mammals (rodents and shrews) but also includes birds, lizards, and snakes. Reproduction is oviparous with mating observed throughout the year and 3–14 eggs per clutch, which are produced once or twice per year. Neonates range in length from 150 to 280 mm. Listed by the IUCN as a Least Concern species and not included in CITES Appendices. Its vernacular name is the Green bush ratsnake, Green tree racer, or Green mountain racer.
Distribution (Figure 19): Bhutan, India (Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, and West Bengal), and Myanmar. Expected to occur in Tibet, China, from 75 to 2560 m. A population of uncertain taxonomic status in southern Laos and Central Vietnam has also been assigned to this species [2].

3.6. Gonyosomini Tribe nov.

GONYOSOMINI trib. nov. (Figure 20).
Type genus: Gonyosoma Wagler, 1828.
Content: Five genera (Gonyophis, Gonyosoma, Rhadinophis, Rhynchophis, and Verdigrophis) containing eight species. Molecular analyses [9,26,27] have revealed that these five genera form a monophyletic clade.
Etymology: the tribal name is based on the genus Gonyosoma, which has precedence and is the oldest and best known among the group of five genera.
Description: Large-sized snakes (adults 1.5–2.4 m). Head distinct from neck. Body elongated and laterally compressed with feebly keeled and/or smooth dorsal scales in 17–27 longitudinal (rarely oblique) rows at midbody. Paravertebral scale row reduction posteriorly to 13–17 rows; paired apical scale pits present, large and elongated in shape and faintly visible to distinct. Ventrals 181–263, angulated with lateral keels and notches. Angulated and keeled subcaudals 88–157. Cloacal shield divided (entire in one species). Eye moderate with round pupil and distinctly colored iris. Nasal entire, divided, or semidivided with a dorsal or ventral suture. Preocular 1, postoculars 2, anterior temporals 1–2 (rarely 3), middle temporals 2–3 (rarely 1 or 4–5), and posterior temporals 2–3 (rarely 4). Supralabials usually 8–10 (but range from 7 to 11) with 3 (rarely 2) entering the orbit. Infralabials usually 9–12 (rarely 13–15) with the first 5 (rarely 6–7) contacting the anterior genials. Anterior/posterior genial length ratio variable. Tail relatively long (19–33% of total length) and prehensile. Umbilicus–vent interval moderate (12–19% of total ventrals). Maxillary dentition aglyphous with 19–23 subequal-sized teeth, 10–13 palatine teeth, 13–21 pterygoid teeth, and 21–26 dentary teeth. Coloration is variable, although most specimens are uniformly some shade of green with black, white, or blue interstitial skin that is exposed during inflation. Color pattern of the head, dorsum, tail, venter, subcaudals, iris, mouth, and tongue vary to some degree. The loreal shield is also variable from typically being single to divided or even absent. The Gonyosomini are arboreal or semiarboreal forest inhabitants, ranging from primary humid tropical rainforests to secondary mixed deciduous subtropical forests, often found in vegetation associated with water. Diurnal, crepuscular, and even nocturnal in activity. Swift and agile climbers with a prehensile tail. Has a diet of mainly mammals and birds that are killed by constriction. Reproductively oviparous with small clutches, usually less than 10 eggs, but with up to four clutches laid per year.
Distribution (Map 12): from Bhutan and northeastern India to southeastern China and Taiwan, thence southward throughout Southeast Asia, as well as the Andamans and the Philippines to Sundaland Indonesia, from sea level to 2800 m [2].

3.7. Gonyosomini Key

Key to the genera and species of the tribe Gonyosomini.
1a.
Rostral appendage present, subtriangular frontal, and internasal length equals width 2 (Rhynchophis).
1b.
Rostral appendage absent, frontal not subtriangular, and internasal length not equal to width 3.
2a.
One elongated loreal, pre- and postocular bars present, ventrolateral light stripe present on tail, and temporals usually 2 + 3 + 3: Rhynchophis boulengeri.
2b.
Two normal loreals, pre- and postocular bars absent, ventrolateral light stripe absent on tail, and temporals usually 2 + 2+ 3: Rhynchophis hainanensis.
3a.
Midbody scale rows 23–27; scales entirely smooth; preocular contacts frontal; umbilicus–vent interval >14% total ventrals; tail uniformly black, red, or brown; and tracheal lung present 4 (Gonyosoma).
3b.
Midbody scale rows 17–19, scales partly/feebly keeled, preocular not contacting frontal, umbilicus–vent interval < 14% total ventrals, tail uniformly green or black with orange rings, and tracheal lung absent 5.
4a.
Tail red to brown; ventrolateral light stripe broad; iris green, blue, or gray; subcaudals light with median zigzag line; and usually two anterior temporals: Gonyosoma oxycephalum.
4b.
Tail black, ventrolateral light stripe absent or narrow, iris yellow or orange, subcaudals uniformly black, and usually one anterior temporal: Gonyosoma janseni.
5a.
Loreal shield absent, supralabials eight, internasal length greater than width, posterior genials longer than anterior genials, iris yellow, ontogenetic color change from juveniles to adult, and frontal narrow with parallel sides: Rhadinophis frenatus.
5b.
Loreal shield present, supralabials nine, internasal width greater than length, posterior genials not longer than anterior genials, iris not yellow, no ontogenetic color change from juveniles to adult, and frontal broad with tapered sides 6.
6a.
Head orange, dorsum multicolored with orange and black rings posteriorly, ventrals > 230, ventrolateral light stripe absent on body and tail, and anterior genials longer than posterior genials: Gonyophis margaritatus.
6b.
Head green or blue, ventrals < 225, spotted ventrolateral stripe present on body, and anterior genials equal in length to posterior genials 7 (Verdigrophis).
7a.
Cloacal shield entire, ventrolateral stripe yellow, iris greenish yellow or olive, mouth pink, and tongue reddish brown: Verdigrophis prasinus.
7b.
Cloacal shield divided, ventrolateral stripe white, iris blue or greenish blue, mouth grey, and tongue brownish yellow: Verdigrophis coeruleus.

4. Summary

The Miocene Epoch, 5.3–23.03 Mya, was a period that saw the decline (Aniliidae, Boidae, Pythonidae, and Tropidophiidae) or extinction (Anomalophiidae, Nigerophhidae, Paleophiidae, and Russellophiidae) of Eurasian henophidian snakes and the rise or modernization of caenophidians (Colubridae, Elapidae, and Viperidae) [95,96]. According to Chen et al. [9], the origin of the Gonyosomini can be traced to the late Early Miocene or early Middle Miocene, approximately 20.47 Mya (CI = 18.0–27.95 Mya). In an earlier study, Burbrink and Lawson [16] placed the origin of the Gonyosoma jansenii and G. oxycephalum clade at 38.1 Mya (CI = 37.1–39.2 Mya) in the Eocene and Elaphe frenata and E. prasina at 24.8 Mya (CI = 24.2–25.5 Mya). The nearest relatives of the Gonyosomini appear to be Coelognathus, which is the basal sister group, and the Lycodontini and Boigini, the two sister clades of the Gonyosomini (Figueroa et al. [97]). Gonyophis and Verdigrophis are sister taxa, and that clade is a sister group to the clade containing Rhynchophis and Rhadinophis, with Gonyosoma being the ancestral sister group to the other four clades.
Among the Gonyosomini, Gonyosoma is unique in comparison with the other four genera in the number of scale rows (23–25 vs. 19), the carination of dorsal scales (entirely smooth vs. partly keeled), and a multicameral tracheal lung (present vs. absent). Rhadinophis is unique from the other genera in the loreal shield (absent vs. present), the number of supralabials (8 vs. 9–11), and the frontal shape (narrow with parallel sides vs. moderate-to-broad with tapered sides). Rhynchophis is unique among the other genera in the rostral appendage (present vs. absent), frontal shape (subtriangular vs. not subtriangular), and internasal shape (length and width subequal vs. length or width greater than the other dimension). Gonyophis is unique among the other genera in genial proportions (anterior longer than posterior vs. posterior longer than anterior), dorsal head color (orange or yellow vs. green, brown, or maroon), and tail color and pattern (black with orange/yellow rings vs. uniformly green). And, Verdigrophis is unique among the other four genera in genial proportions (anterior and posterior length subequal vs. anterior or posterior longer than the other pair). We suggest that the recognition of each of the five clades of the Gonyosomini provides the most taxon information for the phylogenetic history, relationships, and taxonomy of the group. Subsuming all eight species into one genus is less informative and ignores the distinctiveness of the genera.

Author Contributions

Conceptualization, all authors; methodology, all authors; formal analysis, all authors; investigations, all authors; visualization, R.M. and E.H.; data curation, V.W.; writing—original draft preparation, V.W.; writing—review and editing, V.W. and R.M. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Data Availability Statement

All data used in this study are presented in the tables and text.

Acknowledgments

Thanks are due to the curators and staff of FMNH (H. Marx, R.F. Inger, A. Resetar, R.G. Kamei, and J. Mata), ROM (D. Evans and A.J. Lathrop), SDSU (R. Etheridge), and UCM (E. Braker) for the loan of the material that forms the basis of this report. Also, V.W. is indebted to James Hanken and Stevie Kennedy-Gold (MCZ) for approval of the loans and workspace to study the snakes. Emma Hsiao expertly produced the figures of Rhynchophis hainanensis and Verdigrophis coeruleus from photographs.

Conflicts of Interest

The authors declare no conflicts of interest.

Material Examined

Gonyophis margaritatus–FMNH 138677 and 243941; Gonyosoma jansenii–UCM 57840; G. oxycephalum–FMNH 14909, 180107, and SDSU uncatalogued; Rhynchophis boulengeri–ROM 26999 and 34730; Rhadinophis frenatus–FMNH 22345, 24941, and 172322; Verdigrophis coeruleus–FMNH 128282; V. prasinus–SDSU uncatalogued.

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Figure 1. Gonyophis margaritatus (after Peters [33] and Rooij [34]).
Figure 1. Gonyophis margaritatus (after Peters [33] and Rooij [34]).
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Figure 2. Map of Gonyophis margaritatus distribution.
Figure 2. Map of Gonyophis margaritatus distribution.
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Figure 3. Map of Gonyosoma distribution.
Figure 3. Map of Gonyosoma distribution.
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Figure 4. Gonyosoma jansenii (after Schulz [1]).
Figure 4. Gonyosoma jansenii (after Schulz [1]).
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Figure 5. Map of Gonyosoma jansenii distribution.
Figure 5. Map of Gonyosoma jansenii distribution.
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Figure 6. (a) Gonyosoma oxycephalum (after Nutaphand [48]). (b) Gonyosoma oxycephalum (after Schulz [1]).
Figure 6. (a) Gonyosoma oxycephalum (after Nutaphand [48]). (b) Gonyosoma oxycephalum (after Schulz [1]).
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Figure 7. Map of Gonyosoma oxycephalum distribution.
Figure 7. Map of Gonyosoma oxycephalum distribution.
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Figure 8. (a) Rhadinophis frenatus (after Zhao et al. [68]). (b) Rhadinophis frenatus (after Schulz [1]).
Figure 8. (a) Rhadinophis frenatus (after Zhao et al. [68]). (b) Rhadinophis frenatus (after Schulz [1]).
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Figure 9. Map of Rhadinophis frenatus distribution.
Figure 9. Map of Rhadinophis frenatus distribution.
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Figure 10. Map of Rhynchophis distribution.
Figure 10. Map of Rhynchophis distribution.
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Figure 11. (a) Rhynchophis boulengeri (after Bourret [77]). (b) Rhynchophis boulengeri (after Obst et al. [78]).
Figure 11. (a) Rhynchophis boulengeri (after Bourret [77]). (b) Rhynchophis boulengeri (after Obst et al. [78]).
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Figure 12. Map of Rhynchophis boulengeri distribution.
Figure 12. Map of Rhynchophis boulengeri distribution.
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Figure 13. Rhynchophis hainanensis (E. Hsiao from Peng et al. [26]).
Figure 13. Rhynchophis hainanensis (E. Hsiao from Peng et al. [26]).
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Figure 14. Map of Rhynchophis hainanensis distribution.
Figure 14. Map of Rhynchophis hainanensis distribution.
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Figure 15. Map of Verdigrophis distribution.
Figure 15. Map of Verdigrophis distribution.
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Figure 16. (a) Verdigrophis coeruleus (after Zhao et al. [68]). (b) Verdigrophis coeruleus (E. Hsiao from Liu et al. [26]).
Figure 16. (a) Verdigrophis coeruleus (after Zhao et al. [68]). (b) Verdigrophis coeruleus (E. Hsiao from Liu et al. [26]).
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Figure 17. Map of Verdigrophis coeruleus distribution.
Figure 17. Map of Verdigrophis coeruleus distribution.
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Figure 18. (a) Verdigrophis prasinus (after Schleich and Kästle [90]). (b) Verdigrophis prasinus (after Schulz [1]).
Figure 18. (a) Verdigrophis prasinus (after Schleich and Kästle [90]). (b) Verdigrophis prasinus (after Schulz [1]).
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Figure 19. Map of Verdigrophis prasinus distribution.
Figure 19. Map of Verdigrophis prasinus distribution.
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Figure 20. Map of Gonyosomini distribution.
Figure 20. Map of Gonyosomini distribution.
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Table 1. Specific characters of the Gonyosomini. Elev. = elevation in m; ASR, MSR, and PSR = anterior, midbody, and posterior scale rows; C = carination type (S = smooth and k + s = partly keeled and partly smooth); SR = smooth scale rows; KR = keeled scale rows; V = ventrals; C.S. = cloacal shield (D = divided and E = entire); SC = subcaudals; L = loreal (present = 1, absent = 0, S = squarish, and E = elongated); SL = supralabials; SLO = SL entering orbit; Pst = postoculars; AT, MT, and PT = anterior, medial, and posterior temporals; IL = infralabials; AG = IL contacting anterior genials; LOA = total length in mm; RTL = relative tail length (TL/LOA); UVI = umbilicus–vent interval (as % total ventrals); R.A. = rostral appendage; P-F = preocular–frontal contact; Fr = frontal shape (B = broad, M = moderate, N = narrow, T = tapered posteriorly, P = parallel, and S = subtriangular); IN = internasal proportions (L = length and W = width); Max. = maxillary teeth; VLTS = ventrolateral tail stripe; J.C. = juvenile coloration (Gr = green, Gy = gray, O = olive, and B = brown); Eggs = eggs in clutch.
Table 1. Specific characters of the Gonyosomini. Elev. = elevation in m; ASR, MSR, and PSR = anterior, midbody, and posterior scale rows; C = carination type (S = smooth and k + s = partly keeled and partly smooth); SR = smooth scale rows; KR = keeled scale rows; V = ventrals; C.S. = cloacal shield (D = divided and E = entire); SC = subcaudals; L = loreal (present = 1, absent = 0, S = squarish, and E = elongated); SL = supralabials; SLO = SL entering orbit; Pst = postoculars; AT, MT, and PT = anterior, medial, and posterior temporals; IL = infralabials; AG = IL contacting anterior genials; LOA = total length in mm; RTL = relative tail length (TL/LOA); UVI = umbilicus–vent interval (as % total ventrals); R.A. = rostral appendage; P-F = preocular–frontal contact; Fr = frontal shape (B = broad, M = moderate, N = narrow, T = tapered posteriorly, P = parallel, and S = subtriangular); IN = internasal proportions (L = length and W = width); Max. = maxillary teeth; VLTS = ventrolateral tail stripe; J.C. = juvenile coloration (Gr = green, Gy = gray, O = olive, and B = brown); Eggs = eggs in clutch.
SpeciesElevASRMSRPSRCSRKRVC.S.SCLSLSLOPst
margaritatus0–200019–211915–17k + sI–III/VIIV/VII-Vert230–249D108–1301S9 (8,10)3–5/4–6/5–7 (5–6)2
jansenii100–100021–2323–25(13)SAllNone 245–257D130–1401E9–105–7 (6–7)2
oxycephalum20–140023–2723–25 (27)15–17SAllNone229–263D120–1571E (0)9–11 (7,8)4–5/5–6/6–7/4–6
5–7/6–8		2
frenatus170–280019 (21)19 (17)17k + sI–VIIIPV + V198–235D108–14908 (9)3–5/4–62
boulengeri0–20001919 (17,18)15 (13)k + sI–VIVII-V207–227D101–1331E9 (10)4–6/5–72 (3)
hainanenesis80–900191915 (13)k + sVLMD216–221D122–1332S94–62
coeruleus250–165019 (20)19 (15,17)15 (13,17)k + sI–IV/VIV/VII–Vert181–224D88–1281S9 (8,10)4–6 (3–5)2
prasinus75–256019 (17,21)19 (17)15 (13,17)k + sI–V/VIVI/VII–Vert186–209E91–1161S (0)9 (8)4–6 (4–5)2
SpeciesATMTPTILAGLOARTLUVIR.A.P-FFrINMax.VLTSJ.C.Eggs
margaritatus22–32–310–125424–194322.6–33.311.8–13.3NoNoB/TW = 1.5L20–23NoMC?
jansenii1 (2)2–3311–131–5120–237423.7–31.016.7NoYesM/TL = W?NoGr2–9
oxycephalum2 (1,3)2 (4,5)312–151–5 (6,7)170–240020.9–27.714.2–18.7NoYesM/TL = 2W20–25NoGr2–12
frenatus2 (1,3)2–32–3 (4)9–111–5/6120–147522.0–32.512.5–14.1NoNoN/PL > W19–25YesGy/O/B6–12
boulengeri2 (1)3 (2)310–111–5 (6)170–163020.6–30.213.1–13.7YesYesSL = W16–22YesGy/B5–17
hainanenesis22310–121–5150–122922.0–32.5?YesYesSL = W?NoGy6
coeruleus1–22 (1,3)2–39–111–5200–119219.4–27.513.7NoNoB/TL = W20–21NoGr3–11
prasinus1–21–2 (3)2 (3)9–10 (12)1–5 (6)150–135519.4–27.714.4NoNoB/TL = W19–23NoGr3–14
Table 2. Generic characters of the Goniosomini. MSR = midbody scale rows, C = carination (S = smooth and k + s = feebly keeled and smooth), KR = number of keeled scale rows, Lor = loreal number, SL = supralabial number, P/F = preocular–frontal contact (0 = no and + = yes), Fr = frontal width and shape (B = broad, M = moderate, N = narrow, P = parallel, and T = tapered), IN = internasals (L = length and W = width), Gen = genials (A = anterior pair and P = posterior pair), RA = rostral appendage, Head = dorsal head color (G = green, O = orange, R = red, Gr = gray, and Bl = blue), GD = green dorsum (+ = yes and 0 = no), DP = dorsal pattern (U = uniform and R = posterior rings), Tail = dorsal tail color (G = green, B = black, O = orange, R = red, and Br = brown), Iris = iris color (B = black, R = red, O = orange, Y = yellow, Bl = blue, and Br = brown), T.L. = tracheal lung (0 = absent and + = present), MI = interior mouth color (P = pink, G = gray, and Pu = purple), Ont = ontogenetic change of juvenile color and/or pattern to adult (0 = no and + = yes), L.L. = left lung length (% SVL).
Table 2. Generic characters of the Goniosomini. MSR = midbody scale rows, C = carination (S = smooth and k + s = feebly keeled and smooth), KR = number of keeled scale rows, Lor = loreal number, SL = supralabial number, P/F = preocular–frontal contact (0 = no and + = yes), Fr = frontal width and shape (B = broad, M = moderate, N = narrow, P = parallel, and T = tapered), IN = internasals (L = length and W = width), Gen = genials (A = anterior pair and P = posterior pair), RA = rostral appendage, Head = dorsal head color (G = green, O = orange, R = red, Gr = gray, and Bl = blue), GD = green dorsum (+ = yes and 0 = no), DP = dorsal pattern (U = uniform and R = posterior rings), Tail = dorsal tail color (G = green, B = black, O = orange, R = red, and Br = brown), Iris = iris color (B = black, R = red, O = orange, Y = yellow, Bl = blue, and Br = brown), T.L. = tracheal lung (0 = absent and + = present), MI = interior mouth color (P = pink, G = gray, and Pu = purple), Ont = ontogenetic change of juvenile color and/or pattern to adult (0 = no and + = yes), L.L. = left lung length (% SVL).
GenusMSRCKRLorSLP/FFrINGenRAHeadGDDPTailIrisT.L.MIOL.L.
Gonyophis19k + s7–13190B/TW > LA > P0O0RB/OB/R/Br0P01.9
Gonyosoma23–25S019–11+M/TL > WP > A0R/G/Gr/B+UB/R/BrY/O/G/Bl+P05.6–7.5
Rhadinophis19k + s3080N/PL > WP > A0G+UGY0P/Pu+1.3
Rhynchophis19k + s31–29+SL = WP > A+G+UGBr0P+0.8
Verdigrophis19k + s5–11190B/TW > LP = A0Bl/G+UGBl/G0G/P01.4
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MDPI and ACS Style

Wallach, V.; Midtgaard, R.; Hsiao, E. Revalidation of the Arboreal Asian Snake Genera Gonyophis Boulenger, 1891; Rhynchophis Mocquard, 1897; and Rhadinophis Vogt, 1922, with Description of a New Genus and Tribe (Squamata: Serpentes: Colubridae). Diversity 2024, 16, 576. https://doi.org/10.3390/d16090576

AMA Style

Wallach V, Midtgaard R, Hsiao E. Revalidation of the Arboreal Asian Snake Genera Gonyophis Boulenger, 1891; Rhynchophis Mocquard, 1897; and Rhadinophis Vogt, 1922, with Description of a New Genus and Tribe (Squamata: Serpentes: Colubridae). Diversity. 2024; 16(9):576. https://doi.org/10.3390/d16090576

Chicago/Turabian Style

Wallach, Van, Rune Midtgaard, and Emma Hsiao. 2024. "Revalidation of the Arboreal Asian Snake Genera Gonyophis Boulenger, 1891; Rhynchophis Mocquard, 1897; and Rhadinophis Vogt, 1922, with Description of a New Genus and Tribe (Squamata: Serpentes: Colubridae)" Diversity 16, no. 9: 576. https://doi.org/10.3390/d16090576

APA Style

Wallach, V., Midtgaard, R., & Hsiao, E. (2024). Revalidation of the Arboreal Asian Snake Genera Gonyophis Boulenger, 1891; Rhynchophis Mocquard, 1897; and Rhadinophis Vogt, 1922, with Description of a New Genus and Tribe (Squamata: Serpentes: Colubridae). Diversity, 16(9), 576. https://doi.org/10.3390/d16090576

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