Tree-dwelling narrow-mouth frog – Microhyla arboricola – Poyarkov, Vassilieva, Orlov, Galoyan, Tran, Le, Kretova & Geissler, 2014

Science name: Microhyla arboricola – Poyarkov, Vassilieva, Orlov, Galoyan, Tran, Le, Kretova & Geissler, 2014

Taxonomic:  Animalia>> Chordata>> Amphibia>> Anura >> Microhylidae >> arboricola

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

Description:

Physical Characteristics: Microhyla arboricola is a small and moderately slender frog. Males typically measure between 13.2 and 15 mm in snout-vent length, while females range from 15.9 to 17 mm. It has a long, triangular head with a pointed snout that protrudes slightly beyond the lower jaw. The eyes are large and protuberant, and the skin on its back is smooth with a few scattered tubercles.

Coloration: In life, Microhyla arboricola has a pinkish-beige dorsal coloration, with light yellow-brown on the anterior dorsum and head. The posterior dorsum darkens to a light ochre, and the sides of the head are slightly darker than the back. Distinct dark brown stripes run from the snout to the eyes, and the ventral surface is greyish-beige, with darker spots on the throat and belly.

Distribution and habitat:

Altitude: Microhyla arboricola is found at elevations between 1,000 and 1,550 meters above sea level (asl).

Range: This species is currently known from Dak Lak and Khanh Hoa Provinces in south-central Vietnam. The estimated extent of occurrence (EOO) is 7,964 km², consisting of one threat-defined location. Although it is likely to be present in other parts of the Annamite Mountains, its distribution remains limited to these areas until further surveys are conducted.

Habitat: Microhyla arboricola inhabits mixed evergreen forests on mountain slopes and ridges. It is often found in water-filled tree hollows, which are crucial for its reproductive cycle. The species relies on forest habitats, especially during the rainy season when breeding occurs.

Behaviour and ecology:

Lifestyle: Microhyla arboricola is terrestrial and associated with montane forests. It is most active during the rainy season when it reproduces. The species is an obligate phytotelm breeder, laying its eggs in tree hollows.

Reproduction: Breeding begins during the rainy season, and males call to attract females. Clutches of up to 30 eggs are laid on the inner walls of water-filled tree hollows, and after hatching, the larvae drop into the water below, where they develop until metamorphosis. This unique tree-hole breeding behavior makes Microhyla arboricola one of the few frog species in the region to practice oophagy (egg-eating) among its larvae.

Feeding: Although specific dietary data is not available, as a member of the Microhylidae family, Microhyla arboricola is likely insectivorous, feeding on small invertebrates.

Conservation and status:

IUCN Red List Category and Criteria: Microhyla arboricola is listed as Vulnerable under the IUCN Red List criteria B1ab(iii), indicating that the species is at risk due to a limited range and declining habitat quality. The assessment was last conducted in October 2015.

Threats: The primary threats to M. arboricola include habitat destruction due to logging, agricultural expansion, and climate change. The species’ restricted distribution makes it particularly vulnerable to habitat loss, which continues to impact the extent and quality of its montane forest habitats.

Conservation Actions: While no specific conservation measures are in place for Microhyla arboricola, it is found within protected areas such as Chu Yang Sin National Park and Hon Ba Nature Reserve. Conservation efforts should prioritize protecting its montane forest habitat, and further research is needed to better understand its population size, distribution, and reproductive ecology.