Tadung Litter Frog – Leptobrachella tadungensis – (Rowley, Tran, Le, Dau, Peloso, Nguyen, Hoang, Nguyen & Ziegler, 2016)

Science name: Leptobrachella tadungensis – (Rowley, Tran, Le, Dau, Peloso, Nguyen, Hoang, Nguyen & Ziegler, 2016)

Taxonomic:  Animalia>> Chordata>> Amphibia>> Anura >> Megophryidae >> tadungensis

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

Description:

Size and Physical Characteristics: Leptobrachella tadungensis is a small toad, with males measuring between 23.5 and 26 mm in snout-vent length (SVL), while females are slightly larger, with one recorded at 32.1 mm SVL. It has rounded finger tips, a lack of webbing between the toes, and a finely textured dorsal surface. The species has distinct supra-axillary, pectoral, and femoral glands, as well as a prominent black tympanic ring.

Coloration in Life: The dorsal coloration of the toad is dark brown with subtle markings, including dark brown bands on the thighs, tibia, tarsus, and arms. The belly is dark brown with fine white speckling concentrated on the throat, chest, and limbs. The iris is copper-colored with fine black reticulations.

Coloration in Preservative: In preservative, the toad’s vibrant colors fade slightly, but the general pattern of dark brown dorsal coloration and white ventral speckles remains visible.

Distribution and habitat:

Geographic Range: Leptobrachella tadungensis, known as the Ta Dung Litter Toad, is endemic to Ta Dung Nature Reserve in Dak Nong Province, central Vietnam. It inhabits montane forests at elevations between 720 and 1,932 meters above sea level. While currently known only from this area, similar habitats in nearby provinces such as Lam Dong and Dong Nai may also harbor the species.

Elevation: The species has been recorded at elevations ranging from 720 to 1,932 meters above sea level, mainly within the montane evergreen forest zones of Ta Dung Nature Reserve.

Area: The species is restricted to an estimated extent of occurrence (EOO) of 640 km². Its range consists of five or fewer threat-defined locations within the forest, largely limited by dispersal barriers such as mountain ridges.

Habitat: Leptobrachella tadungensis thrives in and around small rocky streams with little flow, located in montane evergreen forests. It prefers the moist, shaded conditions of the forest floor and is closely associated with stream habitats for breeding and calling.

Behaviour and ecology:

Reproductive Biology: The reproductive biology of Leptobrachella tadungensis has not been fully documented. However, like other species in its genus, it is presumed to breed in streams. Males have been recorded calling during the rainy season, particularly in July, suggesting that breeding takes place during this time. A free-swimming larval stage is expected, though tadpoles have not been observed.

Habitat Use: The species is most active during the rainy season, often found near streams and small water bodies. Males call from the ground or under leaf litter in rocky crevices. The toad primarily inhabits undisturbed evergreen forest, relying on the forest floor for foraging and shelter.

Conservation and status:

IUCN Red List Category and Criteria: Leptobrachella tadungensis is currently listed as Endangered under the IUCN Red List criteria B1ab(iii), mainly due to its restricted range and the continuing decline in habitat quality within Ta Dung Nature Reserve.

Population Trend: The population of this species is considered to be decreasing, driven by habitat loss from deforestation and degradation due to agricultural expansion and logging.

Threats: The primary threats to Leptobrachella tadungensis are habitat destruction and fragmentation, particularly from the conversion of montane forest into agricultural land. Logging and forest degradation further contribute to the species’ vulnerability, as it is highly dependent on intact, undisturbed forest habitats.

Conservation Actions: Conservation efforts should prioritize habitat protection within Ta Dung Nature Reserve. It is crucial to halt deforestation and maintain the integrity of montane forests in the region. Additionally, further research is needed to better understand the species’ population size, distribution, and breeding biology.