Ryabov’s Bug-eyed Frog – Theloderma ryabovi – Orlov, Dutta, Ghate & Kent, 2006

Science name: Theloderma ryabovi – Orlov, Dutta, Ghate & Kent, 2006

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

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

Description:

Physical Characteristics:
Theloderma ryabovi is a medium-sized frog with a snout-vent length (SVL) of approximately 43.84 mm. It has a light-beige dorsum with lilac broad patterns and black spots, giving it a lichen-like appearance. The skin on the dorsal side is slightly tuberculous, while the ventral side is smoother, with dark gray coloration and sparse white speckles. The head and body are strongly dorsoventrally depressed, and the snout is elongated and pointed. The large, oval nostrils are situated on high tubercles on the tip of the snout.

The frog has no vomerine teeth and only a short webbing between its third and fourth fingers, while the toes are more fully webbed. Its tympanum is distinct and large, approximately 83% of the eye diameter. The overall body and limb structure, along with its coloration, distinguish Theloderma ryabovi from other species within the genus.

Distribution and habitat:

Altitude:
Theloderma ryabovi is found at an elevation of 1,210 meters above sea level (asl).

Range:
This species is currently known from a single locality in Kon Tum Province, central Vietnam, with an estimated extent of occurrence (EOO) of 2,736 km². The current known population is limited to this site, but it is possible that the species may also be present in nearby areas, such as northeastern Gia Lai Province, where similar habitats and elevations are found. The range has been projected to include these areas of suitable habitat, although further surveys are needed to confirm its presence.

Habitat:
Theloderma ryabovi inhabits montane primary forests and is typically found in trees about 4 meters above the ground. The species is a phytotelm breeder, meaning it breeds in water-filled tree hollows. Adults, tadpoles, and metamorphs have all been observed together in such hollows, indicating a close dependency on this specific microhabitat. The quality of its habitat is under threat due to human activities, and a continuing decline in its extent and quality has been noted.

Behaviour and ecology:

Lifestyle:
This species is arboreal, living in the trees of montane primary forests. Its breeding behavior is closely associated with water-filled tree hollows, where eggs, tadpoles, and adults are often found together. Theloderma ryabovi is thought to have a relatively prolonged breeding season, similar to other species within its genus, with the presence of multiple developmental stages of offspring observed in the same hollow.

Reproduction:
Theloderma ryabovi reproduces in tree hollows filled with water, where the eggs develop into tadpoles. Observations suggest that the breeding season occurs before April, based on the presence of tadpoles and metamorphs during this time. The species is believed to have small clutch sizes, typical of other members of the Theloderma genus, though further research is needed to fully understand its reproductive cycle.

Conservation and status:

IUCN Red List Category and Criteria:
Theloderma ryabovi is currently listed as “Endangered” on the IUCN Red List under the criteria B1ab(iii), indicating its restricted distribution, with only two known threat-defined locations, and ongoing declines in habitat quality. The species was last assessed in 2015.

Threats:
The primary threat to Theloderma ryabovi is habitat degradation due to human activities, such as deforestation for agriculture and other land-use changes. The destruction of montane primary forests, which are critical for the species’ survival, poses a direct threat to both the species and its breeding sites. The species is highly dependent on undisturbed forest environments, making it particularly vulnerable to habitat loss.

Conservation Actions:
Conservation efforts for Theloderma ryabovi should focus on protecting its montane forest habitat. Surveys are needed in adjacent areas to better understand the full extent of the species’ range, and habitat restoration initiatives are critical in areas where deforestation is occurring. Additionally, research into its reproductive biology and population trends is essential to develop effective conservation strategies and ensure its long-term survival. Monitoring its habitat quality and implementing protective measures in key areas will help mitigate the risk of extinction.