Hoabinhensis Flying Frog – Rhacophorus hoabinhensis – Nguyen, Pham, Nguyen, Ninh & Ziegler, 2017

Science name: Rhacophorus hoabinhensis – Nguyen, Pham, Nguyen, Ninh & Ziegler, 2017

Taxonomic:  Animalia>> Chordata>> Amphibia>> Anura >> Rhacophoridae >> hoabinhensis

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

Description:

Physical Characteristics:
Rhacophorus hoabinhensis is a small frog, with males ranging in size from 31.1 to 32.5 mm in snout-vent length (SVL). The head is longer than wide, and the snout is pointed. The frog’s dorsal coloration is yellowish-grey with dark brown blotches. The ventral side, including the thighs and tibia, has a reddish-orange hue. The species lacks vomerine teeth, and its fingers and toes have enlarged discs with distinct circum-marginal grooves. The webbing between the fingers and toes is moderate, allowing for efficient movement in its arboreal habitat.

Distribution and habitat:

Altitude:
Rhacophorus hoabinhensis is found at elevations ranging from 1,230 to 1,350 meters above sea level (asl).

Range:
This species is currently only known from Hang Kia-Pa Co Nature Reserve in Hoa Binh Province, northern Vietnam. Its estimated extent of occurrence (EOO) is 136 km². It is possible that the species’ range extends to adjacent areas with similar habitat and elevations, but further surveys are needed to confirm this. The current distribution is highly limited and has not been extensively studied.

Habitat:
Rhacophorus hoabinhensis is associated with secondary karst forest, which is composed of medium and small hardwoods mixed with shrubs and vines. It is thought to be dependent on karstic environments, where individuals have been observed on branches 1.2–1.5 meters above the ground near small ponds. The species is presumed to breed in water, with a reproductive strategy similar to its congeners, though no females or tadpoles have been documented, and its call remains unknown.

Behaviour and ecology:

Lifestyle:
Rhacophorus hoabinhensis is arboreal, typically found at night on leaves and branches above small ponds. It is nocturnal and is most active between 19:00 and 23:30, foraging and engaging in other activities. The surrounding environment is characterized by secondary karst forest, providing a humid and shaded habitat. The air temperature during recorded observations ranged from 14.8 to 18.9°C, with relative humidity between 84% and 93%.

Reproduction:
The reproductive biology of Rhacophorus hoabinhensis remains largely unknown. However, it is presumed to follow a similar breeding pattern to other Rhacophorus species, possibly involving water-based larval development. No females or tadpoles have been observed, and the species’ call has not been documented.

Conservation and status:

IUCN Red List Category and Criteria:
Rhacophorus hoabinhensis is listed as “Data Deficient” due to the lack of comprehensive information on its population size, trends, and ecological requirements. The species was last assessed in 2020.

Threats:
The primary threat to Rhacophorus hoabinhensis is likely habitat degradation, particularly the loss of karst forests in its range. Expanding agriculture and human activities in the region pose a significant risk to the quality and extent of its suitable habitat. As the species appears to be closely associated with a specific habitat type, any further disturbances could negatively impact its population.

Conservation Actions:
No targeted conservation measures are currently in place for Rhacophorus hoabinhensis. However, its presence within Hang Kia-Pa Co Nature Reserve provides some level of protection. Further field studies are needed to better understand the species’ ecology, population dynamics, and potential threats, as well as to inform appropriate conservation efforts.