Jerdon's tree frog (Hyla annectans): range, size and conservation

Jerdon’s tree frog, Hyla annectans, is a small green tree frog of South and Southeast Asia, also known as the Assam treefrog, the Indian hylid frog or the green leaf frog. It is found in Asia south of the Himalayas: northeast India (Assam, Nagaland, Manipur and Meghalaya), northern Myanmar, northern montane Vietnam and southwestern and central China (Yunnan, Guizhou, Sichuan, Hunan), with isolated populations further west in northwestern Thailand and adjacent Myanmar.

Identification

Adults are modest in size: males measure 28-39 mm snout-vent length, females larger at 32-45 mm. The back is green, with a dark lateral streak, light-edged above, that ends in two or three deep black spots near the groin, itself bright yellow; the thighs are yellow with black spots and the belly white, and the two outer fingers and toes are green. Other marks are a circular tongue with a slight notch, a tympanum about half the diameter of the eye, well-developed toe disks, fingers webbed at the base and toes about two-thirds webbed, smooth skin on the back against a granular underside, and a tuberculated fold running from eye to shoulder.

Habitat and range

Across that range it lives in tropical evergreen and deciduous forest, largely arboreal, at elevations of 600-2,500 m, with records as low as 100 m in India; it also turns up in grassland and agricultural land near forest, rather than only deep woodland.

Behaviour and breeding

Breeding is explosive, concentrated into short bursts rather than spread through the season, and takes place in ponds and terraced paddy fields. Males signal with an external subgular vocal sac and carry black nuptial excrescences on the thumb, used to grip females during amplexus. The use of paddy fields alongside natural ponds lets the species breed close to farmland within its forest range.

Conservation

The facts box gives the species’ IUCN category. It is common in parts of its range, notably China, but faces habitat degradation and water pollution as pressures, and in India it is also collected. Many protected areas fall within its range, which spans five countries.

Similar species

No other Hyla species shares this frog’s range in northeast India and the adjacent hills, so confusion is more likely with an unrelated lookalike than with a true relative. Nasutixalus jerdonii, a shrub frog in the family Rhacophoridae, is also called Jerdon’s tree frog and can be confused with Hyla annectans on name alone, though the two are not closely related and belong to different families.