Helena’s Flying Frog – Rhacophorus helenae – Rowley, Tran, Hoang & Le, 2012

Science name: Rhacophorus helenae – Rowley, Tran, Hoang & Le, 2012

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

Species status: Endemic ; IUCN status: EN (Endangered Species)

Description:

Physical Characteristics:
Rhacophorus helenae, also known as Helen’s Flying Treefrog, exhibits a bright green dorsal color with some individuals having small white spots. The body length ranges from 72.3 to 85.5 mm in males and 89.4 to 90.7 mm in females. The frog has well-developed webbed feet, allowing it to glide between trees. Its ventral side is white, and the limbs display striking blue and yellow patterns, with black markings near the armpits and groin. The frog’s pupils are horizontally oriented, with metallic yellow eyes. Juveniles are pale blue-gray with dark markings that fade as they mature.

Distribution and habitat:

Altitude:
Rhacophorus helenae is found at elevations ranging from 16 to 162 meters above sea level (asl).

Range:
This species is known from four fragmented forest patches in Dong Nai, Binh Thuan, and Ba Ria Vung Tau provinces in southern Vietnam. The known localities are separated by agricultural lands, with distances between the patches ranging from 30 to 90 km. The total estimated extent of occurrence (EOO) is 4,735 km². It is predicted that similar habitats in adjacent areas, such as southeastern Binh Phuoc and northwestern Dong Nai provinces, could potentially support this species, based on ecological niche modeling.

Habitat:
Rhacophorus helenae is associated with mixed lowland forests, typically found in trees or bushes at heights ranging from 0.15 to 7 meters above temporary rain pools. Amplexus (mating) occurs in the canopy, and eggs are laid in foam nests on trees about 10 meters above these pools. Tadpoles fall into the pools upon hatching, completing their aquatic development. The species is dependent on forested wetlands and is affected by the ongoing decline in habitat quality and extent due to expanding agriculture and urbanization.

Behaviour and ecology:

Lifestyle:
Rhacophorus helenae is primarily arboreal and nocturnal, living and foraging in trees within lowland evergreen forests. It is most active during the rainy season, typically from June to August, when it descends to breed. The species deposits eggs in foam nests above temporary pools, and the tadpoles fall into the water upon hatching, where they continue their development.

Reproduction:
Breeding occurs from May to September. Mating takes place in the canopy, and eggs are laid in foam nests on tree branches. Tadpoles drop into the water once they hatch, where they complete their metamorphosis before transitioning to a terrestrial lifestyle. The species exhibits complete metamorphosis, like other amphibians, with distinct aquatic and terrestrial life stages.

Conservation and status:

IUCN Red List Category and Criteria:
Rhacophorus helenae is listed as “Endangered” under the IUCN Red List due to its highly fragmented range and the ongoing loss of its habitat. It was last assessed in 2020.

Threats:
The primary threat to this species is habitat loss and degradation due to the expansion of agriculture and urbanization. Much of its forested habitat is being converted into farmland or urban areas, further fragmenting the population. While the species has been observed in disturbed habitats, this is likely due to agricultural encroachment rather than tolerance to habitat modification.

Conservation Actions:
No specific conservation actions are currently in place for Rhacophorus helenae. However, its known range overlaps with several protected areas, including the Cat Tien National Park and Dong Nai Nature Reserve, which may provide some level of habitat protection. Additional field surveys are required to better understand the species’ population size, distribution, and ecological needs, and to inform targeted conservation efforts.