Yunnan Spiny Frog

Males are about 98mm long; females are about 99mm. The head is slightly flat and wide, with round snout, diamond shaped pupils, horizontal grooves behind the eyes, and hardly visible eardrums. The interorbital space is about the same as the width of its eyelid. The body is sturdy. The dorsal surface is grayish or yellowish palm-brown, with ovary shaped tubercles that are aligned from head to end, round granules among tubercles, and small black protrusions on the granules. The ventral surface is grayish white or yellow, with scattered gray marks. The forelimbs are strong with hardly visible strips; hind legs are short, but the heels of hind legs can meet or overlap. Feet fully webbed, with round toe tips. The fringe outside of the fifth toe only connects to the bottom of the toe. Tarsal fold presents. The ventral surface of the female is smooth. Males have nuptial pads on the inner four toes, a pair of large nuptial pads on the chest, an inner vocal sack beneath the throat, but no male glands. Eggs are about 4mm in diameter, gray or black in color. The tadpoles are about 52mm in length, with head-body lengthabout 20mm. The dorsal is palm-brown in color, with scattered dark marks. The tale is light-palm color, with a dull tip. The labial tooth row is often I:4-4 / II:1-1. One row of lower labial papillae located in the middle, and two rows on the sides.

The Yunnan Spiny Frog resides in rocky streams among mountain forests. The species is found in Southern China provinces: Sichuan (Southeast side: Zhaojue, Yayuan, Muli, Dechang, Huili, Huidong, Pazhihua, Laibo, Mianning, Jiulong), Yunan, Guizhou (Weiting, Suiyang, Songtao, Wangmo, Libo, Xingyi), Hunan (Suining), Hubei (Tongshan?) The elevation ranges from 1330 to 2400m asl in China, and from 800 to 1,000m asl at Sa Pa, Vietnam.

The Yunnan Spiny Frog often squat on moss-covered rocks near creeks. The breeding season is long. Patches of eggs or embryos can be found between April and June. Eggs are often in string shape, half-floating in the stream, while attached to the parts of rocks that are merged in water. The tadpoles live in ponds, and often hide beneath rocks or in fallen leaves.

One main issue is over collection for human consumption. The species is also affected by habitat destruction, agricultural expansion, deforestation, water pollution, and infrastructure development due to human settlement.

Collected for human consumption, the number of wild harvest out of total population has decreased over the past five years.

Nanorana yunnanensis, commonly known as Yunnan paa frog, Yunnan spiny frog, Bourret's paa frog or Bourret's frog, is a species of frog in the family Dicroglossidae. It is found in southwestern China, Vietnam, Myanmar, northern Thailand, and likely in the intervening Laos. Its natural habitats are small and large streams in montane forests, scrub vegetation and grasslands, and it has also been found in ditches. It is threatened primarily by collection for human consumption, but also by habitat loss caused by agricultural development and infrastructure development.

Nanorana yunnanensis are relatively large frogs: males grow to a snout–vent length of about 98 mm (3.9 in) and females to 99 mm (3.9 in). Tadpoles are up to 52 mm (2.0 in) in length.