Larissa’s Flying Frog – Rhacophorus larissae – Ostroshabov, Orlov & Nguyen, 2013

Science name: Rhacophorus larissae – Ostroshabov, Orlov & Nguyen, 2013

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

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

Description:

Physical Characteristics:
Rhacophorus larissae is a medium-sized frog, with males reaching a snout-vent length (SVL) of up to 49.9 mm. The species exhibits a dorsoventrally flattened body with a broad, rounded head. The dorsal skin is smooth, while the belly, throat, and inner thighs are granular in texture. The coloration of the back is typically chocolate brown, adorned with irregular light green markings that begin between the eyes, bifurcate behind the shoulders, and may continue down the sides. The flanks display a combination of white and light green spots, often bordered with black, adding to its distinctive appearance. The ventral side is typically a muddy white, and the limbs show dark brown transverse stripes. The frog’s toes and fingers are equipped with expanded adhesive discs that aid in climbing, and both hands and feet are fully webbed, facilitating its arboreal lifestyle.

Distribution and habitat:

Altitude:
Rhacophorus larissae inhabits high-elevation forests, specifically at around 1,400 meters above sea level (asl).

Range:
This species is native to northern Vietnam, with confirmed records from Nguyen Binh District, Cao Bang Province. The known range includes part of the Pia Oac – Phia Den Nature Reserve, an important protected area in this region. There is potential for Rhacophorus larissae to occur in adjacent areas with similar habitats, including southwestern Guangxi Province, China, but this has not been confirmed. Further surveys in these regions could expand our understanding of the species’ distribution. The exact extent of occurrence (EOO) is not fully established, but the currently known range is small and fragmented.

Habitat:
Rhacophorus larissae is typically associated with subtropical and tropical moist montane forests, particularly evergreen forests on hilly terrain. This species likely spends much of its time in the trees, as it is an arboreal frog, and like many others in its genus, it may breed in still or slow-moving bodies of water such as ponds or streams. Its habitat is under constant pressure from deforestation, primarily due to agricultural expansion and infrastructure development, which threatens the quality and extent of its forested environment.

Behaviour and ecology:

Lifestyle:
As an arboreal species, Rhacophorus larissae spends much of its life in trees, moving among the branches of the forest canopy. It is most active at night (nocturnal) and is believed to rely heavily on its webbed limbs for efficient movement in its arboreal habitat. Little is known about the species’ diet, but like other tree frogs, it likely feeds on small insects and invertebrates found in the forest.

Reproduction:
While specific reproductive details of Rhacophorus larissae are lacking, it is assumed that the species follows a reproductive strategy similar to other members of the Rhacophorus genus. This would include the creation of foam nests in trees or vegetation above water, where eggs are laid. The foam provides protection for the developing embryos, which eventually hatch into tadpoles that drop into water bodies below, where they continue their development into adult frogs. Breeding likely coincides with the rainy season, as this provides the necessary water bodies for tadpole development.

Conservation and status:

IUCN Red List Category and Criteria:
Rhacophorus larissae is listed as “Data Deficient” on the IUCN Red List. This classification reflects the limited information available on the species’ population size, trends, and ecology. The species was last assessed in 2020, and while it inhabits a protected area, its small known range and habitat threats raise concerns about its long-term viability.

Threats:
The primary threat to Rhacophorus larissae is habitat degradation caused by human activities, particularly deforestation for agricultural expansion. The species’ montane evergreen forest habitat is increasingly fragmented by logging and agricultural encroachment. As the species relies on forested environments for shelter, food, and breeding, any significant alteration to these habitats could have severe consequences for its survival. The forests within its range are also under pressure from infrastructure development and illegal logging, further contributing to habitat loss.

Conservation Actions:
Conservation efforts for Rhacophorus larissae should focus on habitat protection and management. The species currently occurs within Pia Oac – Phia Den Nature Reserve, which provides some protection, but ongoing monitoring and management of the reserve are essential to ensure the preservation of its habitat. Expanding the protected areas, curbing deforestation, and promoting sustainable land-use practices are critical for mitigating habitat loss. Further field surveys are needed to determine the species’ full distribution, population status, and ecological requirements. Additionally, research into its reproductive biology, behavior, and adaptability to changing environments would help inform more targeted conservation strategies.