Truong Son Bug-eyed Frog – Theloderma truongsonense – (Orlov & Ho, 2005)

Science name: Theloderma truongsonense – (Orlov & Ho, 2005)

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

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

Description:

Physical Characteristics:
Though specific descriptions of Theloderma truongsonense’s physical characteristics are limited, it likely shares morphological traits common to the genus Theloderma. Members of this genus are typically small to medium-sized frogs with smooth to slightly tuberculated dorsal skin. They often have striking color patterns that help them blend into their natural surroundings, which include tree trunks and leaves. The species likely exhibits a muted coloration for camouflage within its montane forest habitat.

Like other Theloderma species, it may have large, adhesive toe pads, which facilitate its arboreal lifestyle. Its eyes are likely large and forward-facing, characteristic of the genus, giving it a bug-eyed appearance.

Distribution and habitat:

Altitude:
Theloderma truongsonense, also known as the Truong Son Bug-eyed Frog, inhabits montane regions at elevations ranging from 300 to 1,400 meters above sea level (asl).

Range:
This species is native to central Vietnam, with confirmed populations from Quang Binh Province in the north to Khanh Hoa Province in the south. It is also possibly extant in Cambodia and the Lao People’s Democratic Republic (Lao PDR), specifically in areas such as Khammouane, Savannakhet, Salavan, Sekong, and Attapeu Provinces in Lao PDR, and Ratanakiri and Mondulkiri Provinces in Cambodia. The species’ estimated extent of occurrence (EOO) is 181,077 km², and it is likely that further surveys in adjacent regions could extend its known range.

Habitat:
Theloderma truongsonense is primarily associated with subtropical and tropical moist montane forests, though it also occurs in lowland forests. The species inhabits areas near mountain streams, where individuals have been observed. It relies on aquatic environments for reproduction, with clutches of 5-12 eggs found on the back surface of leaves. Additionally, eggs and tadpoles have been observed in tree hollows. The species is highly dependent on healthy forest habitats, and ongoing deforestation and habitat degradation pose significant threats to its population.

Behaviour and ecology:

Lifestyle:
Theloderma truongsonense is an arboreal species that inhabits moist montane forests. Its behavior is closely tied to the aquatic environments within these forests, particularly mountain streams and tree hollows. The species is nocturnal and becomes more active during and after rainfall. It is not migratory, and individuals are often found perched on vegetation near water sources.

Reproduction:
This species reproduces by aquatic larval development. Clutches of 5-12 eggs have been observed laid on the underside of leaves above water, and tadpoles develop in streams or water-filled tree hollows. The presence of eggs and larvae in tree hollows suggests that the species may also be a phytotelm breeder, similar to other Theloderma species. The reproductive season likely corresponds with the wet season, when environmental conditions are most favorable for egg-laying and tadpole development.

Conservation and status:

IUCN Red List Category and Criteria:
Theloderma truongsonense is currently listed as “Least Concern” on the IUCN Red List, as its distribution is relatively widespread, and its extent of occurrence (EOO) is large. Although its population is decreasing due to habitat loss, the decline is not yet severe enough to warrant a higher threat category.

Threats:
The primary threat facing Theloderma truongsonense is habitat loss due to deforestation, agricultural expansion, and infrastructure development. These activities degrade the forest and aquatic environments that the species depends on for survival and reproduction. Logging, road construction, and other human activities contribute to the fragmentation of its montane forest habitat.

Conservation Actions:
Conservation actions for Theloderma truongsonense should focus on habitat protection. The preservation of primary montane forests and freshwater streams is crucial for the long-term survival of this species. Further research is needed to better understand the population trends, reproductive biology, and ecological requirements of the species. Expanding protected areas and conducting regular surveys in both known and potential habitats will help ensure the conservation of this species in the future.