Four-toed Skink – Sphenomorphus tetradactylus – (Darevsky & Orlov, 2005)

Science name: Sphenomorphus tetradactylus – (Darevsky & Orlov, 2005)

Taxonomic:  Animalia>> Chordata>> Reptilia>> Squamata >> Scincidae >> tetradactylus

Species status: Endemic ; IUCN status: LC (Least Concern)

Description: Physical Characteristics:

Size and Build: A slender skink, distinguished by its four fingers on the front legs and five toes on the hind legs.
Scales: It has smooth dorsal scales arranged in 20 longitudinal rows at midbody. The parietal eye spot is absent, and it has four supraoculars, a single loreal, and prefrontals that are weakly marked. The lower eyelid is scaly, and the ear opening is secretive.
Distinctive Traits: The species’ most notable feature is the reduction of fingers on its front limbs, with only four present, which is reflected in its species name, tetradactylus.
Coloration and Appearance:
Sphenomorphus tetradactylus has a relatively plain coloration, with smooth scales that contribute to its slender and agile appearance, suitable for its habitat in rocky, karst environments.

Distribution and habitat: Elevation:
The type locality of Sphenomorphus tetradactylus is situated at an elevation of approximately 300 meters above sea level in Phong Nha-Ke Bang National Park, located in Quang Binh Province, Vietnam.

Area:
This species is known from its type locality in Phong Nha-Ke Bang National Park and has also been recorded from Thuong Hoa and Botrach in Vietnam. It inhabits karst areas and is associated with the limestone massifs within the region.

Habitat:
Sphenomorphus tetradactylus is found in primary evergreen monsoon forests and is known to occupy rocky areas, such as inland cliffs and mountain peaks. Its habitat consists of moist lowland tropical forests, where it lives among the rocky terrain, which provides shelter and food sources. The species is subfossorial, meaning it spends part of its time underground or hidden within rocks.

Behaviour and ecology: Lifestyle:
This species is nocturnal and primarily subfossorial, meaning it is active during the night and spends much of its time burrowing or hiding among rocks. It likely forages for small invertebrates in its forest and rocky habitats. The karst landscape, with its numerous crevices and sheltering places, provides an ideal environment for its subfossorial lifestyle.

Reproduction:
Though the species is known to be oviparous, specific details on its reproductive habits, such as clutch size or breeding season, are not well documented.

Conservation and status: IUCN Red List Category and Criteria:
Sphenomorphus tetradactylus is currently listed as Least Concern on the IUCN Red List. Despite being rare and known only from a few locations, it is not currently believed to be facing immediate threats that would warrant a higher level of concern. The most recent assessment was conducted in 2017.

Population Trend:
The population trend of Sphenomorphus tetradactylus is unknown, as it has only been recorded from a few specimens, and there is no available information on population size or stability.

Threats:
Potential threats to this species may include habitat loss due to deforestation or degradation of karst landscapes. While its habitat within Phong Nha-Ke Bang National Park offers some protection, continued conservation efforts are necessary to ensure its survival.

Conservation Actions:
Although there are no specific conservation actions targeting Sphenomorphus tetradactylus, it benefits from living in Phong Nha-Ke Bang National Park, a protected area. Continued habitat protection and further research are recommended to better understand its ecology and population trends.

Etymology
The species name tetradactylus refers to the presence of only four fingers on the front legs, a distinctive characteristic of this species.