| Golden frog | |
|---|---|
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Amphibia |
| Order: | Anura |
| Family: | Ranidae |
| Genus: | Hylarana |
| Species: | H. aurantiaca |
| Binomial name | |
| Hylarana aurantiaca (Boulenger, 1904) |
|
| Synonyms[1][2] | |
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Hylarana aurantiaca, commonly known as the golden frog, is a species of frog endemic to Sri Lanka and the Western Ghats of India. The species is also known as the Trivandrum frog, the common wood frog, or the small wood frog.
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Hylarana aurantiaca is classified under the genus Hylarana. It belongs to the family of true frogs, Ranidae, under the frog order Anura. Hylarana aurantiaca may be a species complex, but pending revision of its taxonomic status, it is considered a single species. Specimens of golden frogs recovered from Sri Lanka are believed to be another, as of yet, undescribed species.[2]
The species was first described by the Belgian-British zoologist George Albert Boulenger in 1904 as Rana aurantiaca. The type locality of the species is in Trivandrum, and the holotype is preserved in the Natural History Museum (BM 1947.2.2.92 formerly 1903.9.26.1).[3] It was variously classified under the subgenera Hylorana, Hylarana, and Sylvirana while under the genus Rana. It was reclassified under Hylarana when the subgenus was split off from Rana in 2005. It was briefly put in Sylvirana in 2006, but Sylvirana is now considered to be a junior synonym of Hylarana.[4][5]
Golden frogs are small to medium-sized frogs. Mature males grow to 32 to 55.7 mm (1.3 to 2.19 in). Females are larger, growing to 62.6 mm (2.46 in) long.[6]
They have slender bodies with long obtusely pointed snouts. The head is approximately 1 and ⅓ times longer than it is wide. The nares (nostrils) open to the sides, and are about twice as far from the eyes as the tip of the snout.[7] The distance between them is more or less equal to the distance between the eyes. The vomerine teeth are nearer to the choanae than to each other.[8] The tympanum is about the same size as the eye.[9][10] The lower rims of the eyes are reddish in color.[9]
The back (dorsum) of the golden frog is smooth or very finely granulated.[9] It is orange to golden brown in color. It may have small black or brown speckles.[9] A wide dark brown strip at both sides runs from the nostrils to the rear. A narrow but prominent bright yellow or gold-colored fold of skin runs from the back of the eye to the hind legs.[7][10] The upper lip is also golden in color. The underside of the frog is lighter in color than the back, ranging from pale yellow to white.[6][10][11] Younger frogs have brighter colors.[9]
The fingers are long and slender. The first finger is longer than the second, and the third finger is longer than the snout; the tubercles on the underside of the fingers are moderately sized.[8] The tips of the fingers possess enlarged discs, with grooves running around each pad separating the top part from the bottom part.[7][10]
The hind limbs are also long and slender without distinct bars of color. The tibio-tarsal articulation can reach to midway the eye and the snout. The tibia is about six times as long as it is wide and is about half the length of the head and body. It is shorter than the forelimb but is about as long as the foot. The toes are webbed ¾ to ⅔ of the way, with the exception of the outer metatarsals which may be separated almost to the base. The subarticular tubercles are small. They also possess discs at the tips like the fingers.[8]
Males possess an oval humeral gland at the base of the forearms. They also have vocal sacs that visibly inflate when they call.[9]
Golden frogs closely resemble bronzed frogs (Hylarana temporalis) and they are often found together, making it easy to confuse them.[9]
Golden frogs are found in a wide variety of habitats, including lentic (lakes, ponds, and pools) and lotic (rivers, streams, or springs) ecosystems, evergreen forests and scrub, bamboo thickets, coastal areas, and rice paddies.[6][10] They are semi-arboreal and semi-aquatic. Adult golden frogs are commonly found on rocks or perched on leaves and twigs near bodies of water.[9][11]
They are endemic to Sri Lanka and the Western Ghats of India. They can be found 200 to 1,400 m (660 to 4,600 ft) asl in India, and 5 to 660 m (16 to 2,170 ft) asl in Sri Lanka.[2]
Golden frogs are normally nocturnal, though they can become active during light rains in the daytime. The males produce a soft insect-like call. It can be described as "chik chik chik chik chik" or "pti ri ri ri ri" at intervals of 30 seconds.[6][9] Larger males may have lower calls that can be described as "trrrk trrrk trrrrrk".[9] Their main breeding season is between June and July.[10]
The tadpoles are found in stagnant or slow-moving bodies of freshwater.[2] They are brown in color with paler broad tails. They reach a length of 3.1 cm (1.2 in). The body and head of the tadpoles are oval with a rounded snout. The upper blade of the tails extend unto the back. The eyes and nostrils are on the sides, with the nostrils halfway between the eyes and the snout. The opening of the breathing tube is on the upper left side of the body, while the anus is skewed slightly to the right. When fully mature, the tadpoles resemble miniature yellow adult frogs with pinkish tails.[9]
Golden frogs are currently classified as Vulnerable by the International Union for Conservation of Nature and Natural Resources (IUCN). Their numbers are decreasing due to habitat loss. Populations are also highly fragmented due to the development of land for agriculture. They are currently protected in India by legislation.[2]