Robert Inger’s Flying Frog – Rhacophorus robertingeri – Orlov, Poyarkov, Vassilieva, Ananjeva, Nguyen, Sang & Geissler, 2012

Science name: Rhacophorus robertingeri – Orlov, Poyarkov, Vassilieva, Ananjeva, Nguyen, Sang & Geissler, 2012

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

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

Description:

Physical Characteristics:
The males of Rhacophorus robertingeri reach a snout-vent length (SVL) of around 41 mm, while females are larger, reaching up to 59 mm. The coloration of this species is variable, typically with a brownish-yellow dorsal surface and irregular white or orange-yellow spots along the sides. The ventral surface is grayish-yellow, with the intensity of color changing between day and night. The frog’s toes and fingers are webbed, and the adhesive discs on its fingers are larger than those on its toes. A distinctive feature is the small, pointed spur located near the ankle, giving the frog’s legs an elongated appearance. This frog’s limbs are well adapted for an arboreal lifestyle, with webbed feet aiding in climbing and movement through its forest habitat.

Distribution and habitat:

Altitude:
Rhacophorus robertingeri is found at elevations ranging from 400 to 1,700 meters above sea level (asl).

Range:
This species is native to Vietnam, where it has been recorded in montane regions from Binh Thuan Province in the south to Nghe An Province in the north. Although it is primarily known from Vietnam, there is potential for its presence in neighboring regions of eastern Laos, including Bolikhamxai and Khammouan Provinces, where similar habitat exists. The estimated extent of occurrence (EOO) is 193,843 km², encompassing six distinct locations impacted by habitat loss. Surveys are needed to determine its full range, especially in adjacent areas.

Habitat:
Rhacophorus robertingeri is associated with montane streams in dense evergreen forests. It thrives in subtropical and tropical moist montane forest environments and depends on both forested areas and freshwater wetlands for reproduction. During the breeding season, the species is often found near small streams or marshes, where it creates foam nests in vegetation above water. The habitat is vulnerable to deforestation and degradation, which poses a threat to the species’ long-term survival.

Behaviour and ecology:

Lifestyle:
Rhacophorus robertingeri is primarily arboreal, living in the forest canopy but often found near streams, particularly during the breeding season. It is most active from March to June and October to November, especially during and after rainfall. Males call diurnally to attract females, but mating and egg-laying occur at night. Pairs construct foam nests in vegetation overhanging water, where the female deposits 100-500 eggs. After hatching, the larvae collapse the foam nest and are washed into the water by rainfall, where they continue their development as tadpoles.

Reproduction:
Breeding occurs twice a year, from March to June and again from October to November. Eggs are laid in foam nests suspended above water sources. The tadpoles hatch from these nests and are transported into the water by rain, where they grow and metamorphose. The presence of tadpoles has been observed in July, indicating that reproduction can extend into the early rainy season.

Conservation and status:

IUCN Red List Category and Criteria:
Rhacophorus robertingeri is listed as “Least Concern” on the IUCN Red List. Despite facing threats from habitat loss, the species has a wide range, and its population is not currently considered to be severely fragmented. However, its population trend is decreasing, and ongoing habitat degradation could pose a greater risk in the future.

Threats:
The primary threat to Rhacophorus robertingeri is habitat destruction due to deforestation for agriculture and infrastructure development. The loss of forest cover, particularly around streams and wetlands where the species breeds, has a direct impact on its population. The ongoing fragmentation of its habitat is a concern, as it restricts the species’ movement and breeding opportunities.

Conservation Actions:
Conservation efforts for Rhacophorus robertingeri should focus on habitat protection, particularly in the montane forests where it is known to occur. The species is found within some protected areas, but additional conservation measures, such as expanding protected zones and restoring degraded habitats, are needed. Further research is also necessary to monitor population trends, reproductive behavior, and the impact of habitat loss.