We describe a new species of pitvipers from Trang Province of Thailand, near the Thailand–Malaysian border, based on morphological and molecular (2427 bp from cyt b, ND4, and 16S rRNA mitochondrial DNA genes) lines of evidence. Morphologically, Trimeresurus ciliarissp. nov. is distinguished from its congeners by the following combination of morphological characters: a long papillose hemipenis; first supralabial and nasal scale fused; three to four small supraocular scales; internasals not in contact; small scale between nasal and the scale formed by the fused second supralabial and loreal present; dorsal scales in 17–17–15 rows across the body; ventral scales 172–175 in males, 171 in female; subcaudal scales 59–63 in males, 61 in female, all paired; in life an emerald-green dorsum with reddish-brown bands; creamy-white venter lacking dark dots or stripes on the lateral sides of the ventrals; white vertebral spots present in both sexes on every two or three dorsal scales; dark brown spots forming discontinuous pattern present on 1–3 lateral dorsal scale rows; males with reddish-brown postocular stripe. The new species forms a distinct clade on the phylogenetic tree of the genus Trimeresurus and differs from the morphologically similar species T. venustus by a significant divergence in cytochrome b mitochondrial DNA gene sequences (p = 12.5%). The new species is currently known from a small karstic area in the Nakawan Range spanning the border of Thailand and Malaysia, in particular in limestone forests in Trang and Satun provinces (Thailand); it likely also occurs in the adjacent parts of Perlis State (Malaysia). Our study also suggests that the taxonomy of T. kanburiensis species complex requires further studies; in particular our study suggests that the status of populations from Chumphon Province of Thailand and Pulau Langkawi Island of Malaysia should be re-assessed.

A new karst-dwelling, colorful pitviper (Viperidae: Trimeresurus ) from northern Peninsular Thailand

We describe a new species of karst-dwelling pitviper from Chumphon Province of Peninsular Thailand, in the Isthmus of Kra, based on morphological and molecular data (2427 bp from cyt b, ND4 and 16S rRNA mitochondrial DNA genes). Morphologically, Trimeresurus kraensis sp. nov. is distinguished from other congeners by the following combination of morphological characters: a dark/bottle-green dorsum with reddish-brown or purple crossbands; pale green venter lacking dark dots; stripes present on the lateral sides of the ventrals; internasals generally in contact; one large supraocular scale on each side of the head; iris pale copper; tail brown with dark purplish-brown crossbars; dorsal scales in 21–21–15 rows; ventral scales 167 in a single male, 169–171 in females; subcaudal scales 62 in a single male, 52–54 in females, all paired. White vertebral spots present in males, located on approximately every two or four dorsal scales; dark brown spots forming discontinuous pattern present on 1–3 lateral dorsal scale rows; males with reddish-brown postocular stripe with jagged edges. The new species differs from the morphologically similar species Trimeresurus venustus s. str. by a notable divergence in cytochrome b mitochondrial DNA gene sequences (p = 5.9%).

Acute kidney injury (AKI) following Eastern Russell’s viper (Daboia siamensis) envenoming is a significant symptom in systemically envenomed victims. A number of venom components have been identified as causing the nephrotoxicity which leads to AKI. However, the precise mechanism of nephrotoxicity caused by these toxins is still unclear. In the present study, we purified two proteins from D. siamensis venom, namely RvPLA₂ and RvMP. Protein identification using LCMS/MS confirmed the identity of RvPLA₂ to be snake venom phospholipase A₂ (SVPLA₂) from Thai D. siamensis venom, whereas RvMP exhibited the presence of a factor X activator with two subunits. In vitro and in vivo pharmacological studies demonstrated myotoxicity and histopathological changes of kidney, heart, and spleen. RvPLA₂ (3–10 µg/mL) caused inhibition of direct twitches of the chick biventer cervicis muscle preparation. After administration of RvPLA₂ or RvMP (300 µg/kg, i.p.) for 24 h, diffuse glomerular congestion and tubular injury with minor loss of brush border were detected in envenomed mice. RvPLA₂ and RvMP (300 µg/kg; i.p.) also induced congestion and tissue inflammation of heart muscle as well as diffuse congestion of mouse spleen. This study showed the significant roles of PLA₂ and SVMP in snake bite envenoming caused by Thai D. siamensis and their similarities with observed clinical manifestations in envenomed victims. This study also indicated that there is a need to reevaluate the current treatment strategies for Thai D. siamensis envenoming, given the potential for irreversible nephrotoxicity.

The morphological variation, extended distribution, and sequence divergence of a recently described of cobra Naja fuxiShi et al., 2022 captured from mountainous areas in Thailand are evaluated by using molecular and morphological analyses. We investigated the genetic variation and affinities of 72 specimens in the genus Naja by using mitochondrial DNA (cytochrome b and control region) and the nuclear DNA gene, C-mos. Morphological examination was conducted for 33 cobra specimens obtained from the northern, western, and north-eastern regions, and data on their natural history were gathered during field surveys. A high degree of genetic differentiation was shown to exist between the cobras collected from lowlands and those from mountainous areas. N. fuxi occurs in uplands bordering Thailand’s Central Basin, whereas the similar looking N. kaouthia Lesson, 1831 is more or less restricted to the lowlands. All phylogenetic and network analyses supported a distinct clade of N. fuxi from north, west, and, north-east regions. In addition, N. fuxi seems to exhibit a split between the north-eastern population and those from the north and west. The range of N. fuxi probably extends far into the mountainous areas of the neighbouring countries Myanmar, Laos, and Vietnam. Morphologically, N. fuxi in Thailand can be distinguished from all other cobra species in the adjacent Oriental Region. The speciation of cobras in Thailand likely reflects key events in the region’s geographical, climate and environmental history.

The two venomous pit vipers, Trimeresurus macrops and T. hageni, are distributed throughout Thailand, although their abundance varies among different areas. No species-specific antivenom is available for their bite victims, and the only recorded treatment method is a horse antivenom raised against T. albolabris crude venom. To facilitate assessment of the cross-reactivity of heterologous antivenoms, protein profiles of T. macrops and T. hageni venoms were explored using mass-spectrometry-based proteomics. The results show that 185 and 216 proteins were identified from T. macrops and T. hageni venoms, respectively. Two major protein components in T. macrops and T. hageni venoms were snake venom serine protease and metalloproteinase. The toxicity of the venoms on human monocytes and skin fibroblasts was analyzed, and both showed a greater cytotoxic effect on fibroblasts than monocytic cells, with toxicity occurring in a dose-dependent rather than a time-dependent manner. Exploring the protein composition of snake venom leads to a better understanding of the envenoming of prey. Moreover, knowledge of pit viper venomics facilitates the selection of the optimum heterologous antivenoms for treating bite victims.