Trimeresurus Research Articles

Sexual Dimorphism of the Three Pit Viper Species (<i>Gloydius brevicaudus</i>, <i>G. ussuriensis</i>, <i>G. intermedius</i>) in South Korea

Sexual size dimorphism in snakes is closely related to mating behavior and fecundity selection. It provides important information on animal morphology and evolutionary ecology because it allows us to identify key morphological and functional traits between sexes and infer intraspecific competition. In this study, we measured the morphological characters of 147 individuals of three pit viper species stored in the archive of the National Institute of Biological Resources of the Ministry of Environment and confirmed interspecific differences and sexual size dimorphism of each species. We also identified important characters affecting identification using linear discriminant analysis. The results showed that the three pit viper species differed in body and head morphology, and the number of dorsal scale rows was the most important character for species identification. It was found that female red-tongued pit vipers and short-tailed pit vipers were larger than males of each species, while male Central Asian pit vipers were larger than females. Characters related to tail length and head length were confirmed as important characters for interspecific sex discrimination. We compared characters related to head morphology between sexes to find that red-tongued pit vipers showed differences in most characters, while short-tailed pit vipers and Central Asian pit vipers did not. Therefore, short-tailed pit vipers and Central Asian pit vipers are expected to have strong intraspecific competitive pressure. In future studies, it will be necessary to conduct a detailed research on intraspecific competition of short-tailed pit vipers and Central Asian pit vipers with little morphological differences between sexes by examining resource utilization (e.g., food sources and habitats) and ecological niche.

Spatial ecology and microhabitat selection of the nocturnal pitviper Viridovipera stejnegeri (Squamata: Viperidae) in relation to prey.

Habitat is fundamental for facilitating various life activities in animals, for instance, snakes procure essential energy for survival and reproduction by selecting ambush microhabitats. While there has been extensive research on the selection of microhabitat for feeding in terrestrial and aquatic snakes, little is known about arboreal snakes. In the present study, we analyzed the ambush microhabitat preferences of Viridovipera stejnegeri, a widely distributed Asian pitviper in China, conducted association analysis between snake microhabitat and prey microhabitat and abundance to determine the ro5le of microhabitat selection in feeding. Employing random forest analysis and habitat selection functions, we further constructed a predictive framework for assessing the probability of ambush site selection by V. stejnegeri. Our results revealed that V. stejnegeri exhibited a distinct microhabitat preference for ambush prey. Among the 13 environmental factors assessed, V. stejnegeri showed pronounced preferences towards 12 of these factors, including climatic factors, geographical factors, and vegetation factors. Furthermore, although the preferences of V. stejnegeri overlapped substantially with those of its prey across multiple habitat factors, food abundance shows no significant association with various habitat factors of V. stejnegeri, and does not have significant predictive effect on habitat selection of V. stejnegeri. Therefore, we infer that V. stejnegeri does not preferentially select microhabitats with the highest food abundance, which does not support the hypothesis that "snakes select habitats based on the spatial distribution of prey abundance." By analyzing the characteristics of vegetation, geography, and climate, we conclude that V. stejnegeri tends to choose microhabitats with better ambush conditions to increase attack success rate, thereby achieving the optimal feeding success rate at the microhabitat scale, which is in line with the predictions of optimal foraging theory. This study provides new insights into the predation ecology and habitat selection of snakes.

A new species of pit-viper from the Ayeyarwady and Yangon regions in Myanmar (Viperidae, Trimeresurus).

In a genomic study by Chan and colleagues, pit-vipers of the Trimeresuruserythrurus-purpureomaculatus complex from the Ayeyarwady and Yangon regions in Myanmar were demonstrated to be a distinct species based on robust population genetic and species delimitation analyses. Here, we provide morphological characterizations and a formal description of those populations as a new species. The new species, Trimeresurusayeyarwadyensissp. nov., is most closely related to T.erythrurus and T.purpureomaculatus and shares morphological characteristics with both of those species. Some specimens of T.ayeyarwadyensissp. nov. have green dorsal coloration and no distinct dorsal blotches (a trait shared with T.erythrurus but not T.purpureomaculatus), while others have dark dorsal blotches (a trait shared with T.purpureomaculatus but not T.erythrurus). The distinct evolutionary trajectory of the new species, coupled with the lack of obvious morphological differentiation, represents a classic example of the cryptic nature of species commonly found in the Trimeresurus group of Asian pit-vipers and underscores the need for data-rich analyses to verify species' boundaries more broadly within this genus.

Systematics of Trimeresurus popeiorum Smith, 1937 with a revised molecular phylogeny of Asian pitvipers of the genus Trimeresurus Lacépède, 1804 sensu lato

The pit viper snake genus Trimeresurus Lacépède, 1804 sensu lato, is a diverse group of nocturnal serpents comprising over 61 species. The genus is morphologically heterogeneous and has been divided into several subgenera. We present an updated phylogeny of Asian pitvipers and propose a revised classification. Additionally, we revise the taxonomy of T. popeiorum Smith, 1937 and propose taxonomic changes with support from molecular and morphological data. We restrict T. popeiorumsensu stricto to northeastern India, Bangladesh, southern China, and northern Myanmar; populations beyond these areas require further assessment. We also synonymize T. yingjiangensisChen et al., 2019 with T. popeiorum based on overlapping morphological characters, molecular data, and distribution. The findings shed new light on the taxonomy of T. popeiorum, warranting the need for assessing the population of T. popeiorum from southeast Asia.

New insights into the phylogeny and evolution of Chinese Ovophis (Serpentes, Viperidae): Inferred from multilocus data

AbstractThe Asian pitviper genus Ovophis is a group of venomous snakes widely distributed in mid to high elevation mountains in Asia, and presently five species are recognised. However, its systematics, species diversity and species distribution boundaries remain poorly understood. We reconstructed the phylogenetic relationships and explored species diversity of Chinese Ovophis based on two mitochondrial fragments (Cyt b and ND4) and four nuclear genes (BACH1, c‐mos, Rag1, NT3) and also conducted a morphological comparison between focal species. Our results indicated that the species diversity had been underestimated within Ovophis and we described a population from southern Yunnan, China, as a new taxon, naming it as Ovophis malhotrae sp. nov. Based on more extensive sampling, we redefined the distribution of O. monticola and O. makazayazaya in China. Divergence date estimation suggested that Ovophis originated at about 16.79 Ma in the middle Miocene.

Thromboelastographic evaluation in dogs with Asian pit viper (Gloydius) envenomation.

The objective of this study was to investigate the thromboelastography (TEG) variables and platelet count after Asian pit viper (Gloydius) envenomation in dogs compared with healthy control dogs. Ten dogs with snake envenomation and twenty healthy dogs were included. There was a significant decrease in G (P=0.017), maximum amplitude (MA) (P=0.012), angle value (P=0.041), platelet count (P<0.001, as well as an increase in K value (P=0.034) and R value (P=0.007) in dogs with snake envenomation. The results of this study revealed that dogs with Asian pit viper (Gloydius) envenomation showed a hypocoagulable state compared with healthy dogs. Our findings may support the use of TEG for diagnosing and monitoring coagulopathy after Asian pit viper (Gloydius) envenomation in dogs.

Predicting the Distribution of Three Korean Pit Viper Species (&lt;i&gt;Gloydius brevicaudus&lt;/i&gt;, &lt;i&gt;G. ussuriensis&lt;/i&gt;, and &lt;i&gt;G. intermedius&lt;/i&gt;) under Climate Change

Climate change can pose severe threats to wildlife populations causing population declines and destroying their habitats. Particularly, pit vipers belonging to reptiles, poikilotherm, are vulnerable to climate change due to their narrow movement range and low dispersal capability. This study aimed to identify pit viper species vulnerable to climate change using their predicted geographical habitat range based on the current and future Korean pit viper species distribution model. The results of this study showed that three major environmental factors related to altitude and temperature (BIO4 and BIO5) influenced the habitat distribution of three pit viper species. These factors showed significant variation between increased, maintained, and decreased habitat areas of the species due to climate change. It was also predicted that the habitat of Korean pit vipers would decrease by more than 80% under the RCP 8.5 scenario. Especially, Central Asian pit viper was predicted to lose 98.52% of its habitat, indicating that it would be the most vulnerable species to climate change. Although we confirmed that forest areas around the Taebaek Mountains, known as current major distribution areas of pit vipers, would provide maintained or even increased habitat areas to these species along climate change, habitable space for the vipers was still predicted to be very narrow. Therefore, it is critical to protect the forest areas around the Taebaek Mountains to minimize the impact of climate change on Korean pit vipers. Moreover, since some populations of Central Asian pit viper, most vulnerable to climate change, are geographically isolated, it will be necessary to establish systematic conservation measures by determining the protection priority of populations through studying genetic diversity between populations. We believe that the results of this study will provide an important basis for establishing management measures in designating the habitat of a threatened population due to climate change as a protected area.

Genetic diversity and sex-biased dispersal in the brown spotted pitviper (Protobothrops mucrosquamatus): Evidence from microsatellite markers.

Dispersal plays a vital role in the geographical distribution, population genetic structure, quantity dynamics, and evolution of a species. Sex‐biased dispersal is common among vertebrates and many studies have documented a tendency toward male‐biased dispersal in mammals and female‐biased dispersal in birds. However, dispersal patterns in reptiles remain poorly understood. In this study, we explored the genetic diversity and dispersal patterns of the widely distributed Asian pitviper Protobothrops mucrosquamatus. In total, 16 polymorphic microsatellite loci were screened in 150 snakes (48 males, 44 females, 58 samples without sex information) covering most of their distribution. Microsatellite analysis revealed high genetic diversity in P. mucrosquamatus. Bayesian clustering of population assignment identified two major clusters for all populations, somewhat inconsistent with the mitochondrial DNA phylogeny of P. mucrosquamatus reported in previous research. Analyses based on 92 sex‐determined and 37 samples of P. mucrosquamatus from three small sites in Sichuan, China (Mingshan, Yibin, and Zizhong) consistently suggested female‐biased dispersal in P. mucrosquamatus, which is the first example of this pattern in snakes. The female‐biased dispersal patterns in P. mucrosquamatus may be explained by local resource competition.

Phylogenetic relationships between three Korean pit viper Gloydius (Serpentes: Crotalinae) species using mitochondrial DNA genes.

Molecular phylogenetic studies of the Asian pit viper genus Gloydius have been widely published in Asia, but Korea population have not been conducted till date. This study aimed to analyze the phylogenetic relationships of three Gloydius species (G. saxatilis, G. brevicaudus, and G. ussuriensis) from Korea with other Gloydius species, based on Cytochrome b and ND4. We compared 160 samples representing the three species with those of 17 reference species and their phylogenetic status and genetic diversity were analyzed with concatenated sequences of two mitochondrial DNA. Korean G. brevicaudus and G. saxatilis showed high haplotype diversity and relatively low and moderate nucleotide diversity, respectively. Although G. ussuriensis showed high genetic diversity, it was low in the Baengnyeong Island population. The phylogenetic tree represented two major lineages. One major lineage comprised G. ussuriensis, G. tsushimaensis, G. blomhoffii, and G. brevicaudus. The Chinese G. ussuriensis belonged to the same clade as the Korean G. ussuriensis and was closely related to the Baengnyeong Island population. Moreover, G. tsushimaensis was closely related to G. ussuriensis from southwestern Korean and Jeju Island populations. The other major lineage comprised the remaining 12 species and G. saxatilis. Korean G. saxatilis was closely related to G. saxatilis, G. shedanoensis, and G. intermedius from China. The phylogenetic status of the Korean Gloydius species in comparison with the other Gloydius species was identified. We suggesting the conservation management unit for the Baengnyeong Island population, while the current conservation status of Korean G. saxatilis is suggested to be revised to a higher level.

Socio-Economic Manifestation Dealing with a Proven Green Pit Viper (&lt;i&gt;Cryptelytrops sp&lt;/i&gt;.) Envenomation- A Case from Nalagad Municipality, Jajarkot, Karnali Province, Nepal

This case documents envenomation by a Green pit viper (Cryptelytrops sp.), a species found in South and Southeast Asia that causes the majority of venomous snakebites among Southeast Asian pit vipers. The proven life-threatening cases described in published literature, however, are sparse. We report a case of noticeable envenomation due to confirmed Green pit viper, Cryptelytrops sp. bite in Jajarkot. This is the first known reported case of such a bite from Jajarkot in Nepal. This case highlights the urgent need to improve diagnosis, monitoring, and supportive care for snakebite victims in Nepal.

Distribution Patterns and Ecological Niches of the Red-tongued Pit Viper (&lt;i&gt;Gloydius ussuriensis&lt;/i&gt;) and the Central Asian Pit Viper (&lt;i&gt;Gloydius intermedius&lt;/i&gt;) in Cheonmasan Mountain, South Korea

Studies on the distribution of species are important to understanding the interspecific ecological niche and habitat selection through geographic environmental information. Particularly, vipers in the same genus have been an important topic because they show differences in the preferred geographical environment, depending on the distance of the phylogenetic relationship. This study investigated the geographical environment of red-tongued pit vipers (Gloydius ussuriensis) and Central Asian pit vipers (Gloydius intermedius) in the mountainous area, Cheonmasan Mountain County Park, South Korea, from April 2012 to October 2014, to understand the relationships among their habitat characteristics and ecological niche. Red-tongued pit vipers mainly lived in low altitude, wet valley areas with a low solar reflectance, while Central Asian pit vipers inhabited high altitude, dry land with large amounts of sunshine. As a result, our study supports that the ecological niche of red-tongued pit vipers and Central Asian pit vipers, inhibiting in Cheonmasan Mountain was overlapped low according to the majority of geographical environmental variables. The differentiated diet preference might be took into consideration as one of the potential key factors to the ecological niche differentiation among two species.

Molecular phylogenetic analysis of the genus Gloydius (Squamata, Viperidae, Crotalinae), with description of two new alpine species from Qinghai-Tibet Plateau, China.

We provide a molecular phylogeny of Asian pit vipers (the genus Gloydius) based on four mitochondrial genes (12S, 16S, ND4, and cytb). Sequences of Gloydiushimalayanus, the only member of the genus that occurs south of the Himalayan range, are included for the first time. In addition, two new species of the genus Gloydius are described based on specimens collected from Zayu, Tibet, west of the Nujiang River and Heishui, Sichuan, east of the Qinghai-Tibet Plateau. The new species, Gloydiuslipipengi sp. nov., can be differentiated from its congeners by the combination of the following characters: the third supralabial not reaching the orbit (separated from it by a suborbital scale); wide, black-bordered greyish postorbital stripe extending from the posterior margin of the orbit (not separated by the postoculars, covering most of the anterior temporal scale) to the ventral surface of the neck; irregular black annular crossbands on the mid-body; 23-21-15 dorsal scales; 165 ventral scales, and 46 subcaudal scales. Gloydiusswildsp. nov. can be differentiated from its congeners by the narrower postorbital stripe (only half the width of the anterior temporal scale, the lower edge is approximately straight and bordered with white); a pair of arched stripes on the occiput; lateral body lakes black spots; a pair of round spots on the parietal scales; 21 rows of mid-body dorsal scales; zigzag dark brown stripes on the dorsum; 168–170 ventral scales, and 43–46 subcaudal scales. The molecular phylogeny in this study supports the sister relationship between G.lipipengisp. nov. and G.rubromaculatus, another recently described species from the Qinghai-Tibet Plateau, more than 500 km away, and indicate the basal position of G.himalayanus within the genus and relatively distant relationship to its congeners.

First record of Salazar’s Pitviper (Trimeresurus salazar) from Meghalaya, India, with comments on hemipenes

First record of Salazar’s Pitviper (Trimeresurus salazar) from Meghalaya, India, with comments on hemipenes

The complete mitochondrial genome of the Asian pitviper Gloydius changdaoensis (Squamata, Viperidae)

Asian pitviper Gloydius changdaoensis is a coastal species, distributed in Shandong province, China. In this study, we successfully sequenced the mitochondrial genome of one individual of G. changdaoensis. The complete mitochondrial genome is circular molecular with 17,224 bp, containing an origin of light-strand replication (OL), two non-coding control regions (CRs), and 37 classical genes of vertebrate, which contain 13 protein-coding genes (PCGs), 2 ribosomal RNA genes, and 22 transfer RNA genes. A Bayesian phylogenetic tree using the complete mitochondrial genomes of all viper species available showed a consistent result with previous studies.

Clinical implications of coagulotoxic variations in Mamushi (Viperidae: Gloydius) snake venoms

Snake bite is currently one of the most neglected tropical diseases affecting much of the developing world. Asian pit vipers are responsible for a considerable amount of envenomations annually and bites can cause a multitude of clinical complications resulting from coagulopathic and neuropathic effects. While intense research has been undertaken for some species of Asian pit viper, functional coagulopathic effects have been neglected for others. We investigated their effects upon the human clotting cascade using venoms of four species of Gloydius and Ovophis okinavensis, a species closely to Gloydius. All species of included within this investigation displayed varying fibrinogenolytic effects, resulting in a net anticoagulant outcome. Gloydius saxatilis and Gloydius ussuriensis displayed the most variable effects from differing localities, sampled from Russia and Korea. As this Gloydius investigation includes some geographical variation, notable results indicate key variations of these species that point to possible limitations in antivenom cross-reactivities, which may have implications for the clinical care of victims envenomed by these snakes.

Basal but divergent: Clinical implications of differential coagulotoxicity in a clade of Asian vipers

Envenomations by Asian pitvipers can induce multiple clinical complications resulting from coagulopathic and neuropathic effects. While intense research has been undertaken for some species, functional coagulopathic effects have been neglected. As these species' venoms affect the blood coagulation cascade we investigated their effects upon the human clotting cascade using venoms of species from the Azemiops, Calloselasma, Deinagkistrodon and Hypnale genera. Calloselasma rhodostoma, Deinagkistrodon acutus, and Hypnale hypnale produced net anticoagulant effects through pseudo-procoagulant clotting of fibrinogen, resulting in weak, unstable, transient fibrin clots. Tropidolaemus wagleri was only weakly pseudo-procoagulant, clotting fibrinogen with only a negligible net anticoagulant effect. Azemiops feae and Tropidolaemus subannulatus did not affect clotting. This is the first study to examine in a phylogenetic context the coagulotoxic effects of related genera of basal Asiatic pit-vipers. The results reveal substantial variation between sister genera, providing crucial information about clinical effects and implications for antivenom cross-reactivity.

Description of cranial elements and ontogenetic change within Tropidolaemus wagleri (Serpentes: Crotalinae).

Tropidolaemus wagleri is a species of Asian pitviper with a geographic range including Thailand, Vietnam, Malaysia, Singapore, Bruniei, parts of Indonesia, and the Philippines. Tropidolaemus is a member of the Crotalinae subfamily, within Viperidae. The genus Tropidolaemus includes five species, and was once included within the genus Trimeresurus. While some osteologic characteristics have been noted a comprehensive description of cranial elements has not been produced for T. wagleri. An in-depth description of the cranial skeleton of Tropidolaemus wagleri lays the foundation for future projects to compare and contrast other taxa within Crotalinae and Viperidae. The chosen reference specimen was compared to the presumed younger specimens to note any variation in ontogeny. The study here provides a comprehensive description of isolated cranial elements as well as a description of ontogenetic change within the specimens observed. This study contributes to the knowledge of osteological characters in T. wagleri and provides a foundation for a long term project to identify isolated elements in the fossil record.

Evolutionary history and postglacial colonization of an Asian pit viper (Gloydius halys caucasicus) into Transcaucasia revealed by phylogenetic and phylogeographic analyses

It has been generally acknowledged that glacial climates at the time of the Pleistocene altered the patterns of species distributions, prompting latitudinal and altitudinal distribution shifts in several species, including poikilothermic species commonly known for their thermal sensitivity. However, the historical phylogeographic patterns of such species have remained largely unknown. Here, we present the historical biogeographic, phylogenetic, and phylogeographic relationships of the Caucasian pit viper, G. h. caucasicus, based on two mtDNA (cyt b and ND4) and one nDNA (c-mos) genes. This pit viper represents the westernmost member of the Crotalinae subfamily in the Palearctic and occurs in a variety of habitats, from 30 m to 3,000 m above sea level. In Iran, it is distributed on the northern and southern slopes of the Alborz Mountains, rendering it a target for phylogenetic and phylogeographic studies of a terrestrial poikilothermic animal. Our study identified four Iranian lineages of G. h. caucasicus along the northeastern to northwestern slopes of the Alborz Mountains and southern Azerbaijan (Talysh Mountains). Diversification of the Iranian lineages highlights population expansion and subsequent isolation into four plausible refugial areas during the Quaternary paleo-climatic oscillations, confirmed by our molecular dating and historical biogeographic analyses. The results of coalescence-based simulations support the incursion of the species from northeastern Iran to the western end of the Alborz, and then toward Transcaucasia via two directions: northern and southern slopes of the Alborz Mountains. Furthermore, our results clearly implied that G. h. caucasicus should be elevated to species rank and further referred to as G. caucasicus (Nikolsky, 1916).

Multilocus phylogeography of the brown-spotted pitviper Protobothrops mucrosquamatus (Reptilia: Serpentes: Viperidae) sheds a new light on the diversification pattern in Asia

Understanding the influence of geographical events and climate changes on genetic diversity is essential in explaining current patterns of genetic structure and geographic distribution of organisms. We inferred phylogenetic relationships, investigated historical demography, explored the evolutionary history, and clarified intraspecific taxonomy of Protobothrops mucrosquamatus, which is one of the commonest and most wide-ranging Asian pitvipers. A total of 184 samples from 54 localities were sequenced and analyzed for two mitochondrial gene fragments and two nuclear genes. Phylogenetic reconstruction based on mtDNA sequences revealed the existence of a minimum of five geographically structured and well-supported lineages within P. mucrosquamatus. Based on the mtDNA gene tree, and the geographic relationship between populations allied by matrilineal lineages, a complex longitudinal and latitudinal diversification pattern was uncovered in P. mucrosquamatus. The estimated date of the origin of the species (about 5.3 Ma) and divergence of the intraspecific lineages match the rapid uplifting of Qinghai-Xizang Plateau, and is also consistent with those of some other co-distributed Asian pitvipers. Formation of the two island lineages (Taiwan and Hainan) was generally congruent with the first isolation of the islands, but the two lineages showed different relationships with the continental Asian populations in comparison with some other pitvipers. Population historical demographic analyses, based on three methods, showed that all lineages have experienced slight population expansion in and around the Dali Glacial. Tests of intraspecific taxonomy indicated that no cryptic taxon is present within this widely distributed snake.

A novel pentameric phospholipase A2 myotoxin (PophPLA2) from the venom of the pit viper Porthidium ophryomegas

The first toxin isolated from the venomous pit viper Porthidium ophryomegas is a basic pentameric phospholipase A2 (PophPLA2). Elucidation of its amino acid sequence showed that it belongs to the group IIA of secreted PLA2s, with the presence of all 14 conserved cysteine positions. The toxin displayed catalytic activity, in agreement with the presence of Asp49 in its sequence of 121 residues. SDS-PAGE analysis revealed that this toxin is pentameric in non-reducing conditions, a structural organization that has not been described for any viperid PLA2. PophPLA2 displayed moderate myotoxic (in vivo) and cytotoxic (in vitro) activities, as well as anticoagulant activity on human plasma (in vitro). PophPLA2 was not lethal, and did not induce signs of toxicity or distress in mice, when administered intravenously at a dose of up to 100 μg (5.9 μg/g). The toxin showed highest sequence identity with other PLA2s from the venoms of ancestral Asian pit viper species.