Golden Bug-eyed Frog – Theloderma auratum – Poyarkov, Kropachev, Gogoleva & Orlov, 2018

Science name: Theloderma auratum – Poyarkov, Kropachev, Gogoleva & Orlov, 2018

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

Species status: Endemic ; IUCN status: VU (Vunerable)

Description:

Physical Characteristics:
Theloderma auratum is a small-sized frog, with males ranging from 21.8 to 26.4 mm in snout-vent length (SVL). The frog has a smooth dorsal surface, lacking the warts or asperities seen in some of its congeners. The species exhibits a golden-yellow dorsal coloration, often with sparse golden-orange speckling or reticulations and small dark-brown spots. Its ventral surfaces are greyish-blue with indistinct brown blotches. One of its distinguishing features is its bicolored iris, which is golden-orange on the upper part and black with copper-red flecks on the lower part, creating a striking appearance.

The species has no webbing between its fingers, but its toes are half-webbed, which assists in its semi-aquatic lifestyle. Its snout is elongated and tapering, and vomerine teeth are absent. The smooth skin on the dorsal side and the pointed snout distinguish Theloderma auratum from closely related species within the genus.

Distribution and habitat:

Altitude:
Theloderma auratum, commonly known as the Golden Bug-eyed Frog, inhabits montane regions at elevations ranging from 800 to 1,420 meters above sea level (asl).

Range:
This species is native to Vietnam, with known populations in Gia Lai, Kon Tum, and Thua Thien-Hue provinces. It has a restricted range and an estimated extent of occurrence (EOO) of approximately 19,292 km². Although its presence has been confirmed in these provinces, further surveys might reveal the species in neighboring areas, such as the eastern part of the Lao People’s Democratic Republic (Lao PDR), where similar habitats are found.

Habitat:
The Golden Bug-eyed Frog is primarily associated with primary montane evergreen forests. Individuals are typically found perched on vegetation up to nearly a meter above the ground, particularly after heavy rainfalls. The species appears to be highly dependent on undisturbed forest habitats, and there have been no reports of Theloderma auratum in degraded or disturbed areas. Due to its dependence on high-quality habitats, ongoing deforestation and habitat degradation are significant concerns for its population.

Behaviour and ecology:

Lifestyle:
This species is highly arboreal and is typically found on trees or vegetation in its montane forest habitat. Individuals are usually observed after or during heavy rain, suggesting that weather conditions play a role in their activity patterns. Although little is known about their specific reproductive biology in the wild, Theloderma auratum is thought to be a phytotelm breeder, similar to related species. In captivity, males have been observed calling in May, and tadpoles were noted in June. The species appears to breed in small water-filled tree hollows or on surfaces slightly above the water, where tadpoles develop.

Reproduction:
Under laboratory conditions, Theloderma auratum has been observed to lay one or two eggs at a time on surfaces slightly above water. The tadpoles take about 2.5 months to metamorphose, and during this time, they remain in their water-filled nests. In the wild, their reproductive cycle may involve breeding in tree hollows, although this has not been definitively confirmed. Further studies are needed to better understand the reproductive habits and developmental stages of the species in its natural environment.

Conservation and status:

IUCN Red List Category and Criteria:
Theloderma auratum is currently listed as “Vulnerable” on the IUCN Red List under the criteria B1ab(iii), indicating a restricted distribution with continuing decline in the extent and quality of its habitat. The species was last assessed in 2020, and its population trend is currently considered to be decreasing.

Threats:
The main threat facing Theloderma auratum is habitat loss due to deforestation and land-use changes in its montane forest habitat. Logging, agricultural expansion, and other human activities contribute to the fragmentation and degradation of the forests on which this species depends. As a forest-dependent species, any decline in the extent or quality of its habitat directly threatens its survival.

Conservation Actions:
Conservation efforts for Theloderma auratum must focus on protecting its primary forest habitat from further degradation. Given its limited distribution and dependence on undisturbed montane forests, the preservation of these areas is crucial. Further research is needed to better understand the population size, distribution, and reproductive behavior of the species. Additionally, establishing protected areas in regions where the species occurs, and conducting regular monitoring of its population and habitat quality, are essential steps in ensuring its long-term survival.