Polypedates otilophus (File-Eared Tree Frog) is a medium to large sized frog; males range from 64-80 mm and females from 82-97 mm (Inger and Stuebing 1997). The head is triangular (Inger and Stuebing 1997) and longer than it is broad (Malkmus 2002), with a protruding, sharp point at the angle of the jaw (Inger and Stuebing 1997), though somewhat rounded in profile (Malkmus 2002). Pupils are horizontal, with yellowish gray irises (Malkmus 2002). Eye-nostril distance is more than twice the nostril-snout distance (Inger 1966). The tympanum is conspicuous, oval-shaped, with a horizontal diameter 3/4 of the eye diameter (Inger 1966). There is a serrated, bony ridge behind the eye and above the tympanum (Iskandar 2004). Vomerine teeth are present in oblique groups between the choanae, and closer to the choanae than to each other (Inger 1966). The body is generally robust, with slender limbs (Inger 1966), though on Borneo this frog may have a compressed body and long limbs (Malkmus 2002). Skin above is generally smooth and may have whitish spinose asperities (Inger 1966). The sides and abdomen are coarsely granular (Malkmus 2002). There is a small pointed projection at the heel with a smaller one at the elbow (Inger and Stuebing 1997), as well as 4-6 white tubercles below the vent and sometimes a white dermal fringe above it (Inger 1966). Finger tips are expanded into large discs, with the outermost only slightly narrower than tympanum diameter; the toe tips are also expanded, but much less so than the outer finger tips (Inger 1966). Webbing is rudimentary between 1st and 2nd fingers and absent between outer ones; toes are webbed over half to almost full length (Malkmus 2002). Supernumerary tubercles are present on the metacarpals. An oval inner (no outer) metatarsal tubercle is present (Inger 1966). Males have median subgular vocal sacs with round, bilateral openings near the jaw commissures (Inger 1966). Nuptial pads are grayish or yellowish velvety structures on the first and second fingers (Inger 1966). Pink lineae masculinae are present at the dorsal and ventral borders of the obliquus muscle (Inger 1966).
Dorsal coloration varies from light brown or gray to yellowish brown or bright yellow (Malkmus 2002; Iskandar 2004). Ventral coloration is generally cream-colored (Inger 1966) or dirty white (Malkmus 2002). Numerous thin black stripes run down the back from the head; the inguinal region has black lines and dots; and the thighs have 7-11 narrow black bars on the anterior and posterior faces (Malkmus 2002).
Total length of tadpoles reaches a maximum of 80 mm (Malkmus 2002). Tadpoles have spheroidal bodies with the top of the head flattened and dorsolaterally placed eyes, visible from below (Inger 1966). Nostrils are much closer to the tip of the snout than to the eye, with eye-nostril distance equal to the internarial distance(Inger 1966). The tail is convex, deepest at the center and tapering to a long narrow tip, with a weak caudal muscle and both fins deeper than muscle beyond the basal third of the tail (Inger 1966). The spiracle is sinistral and non-tubular, located below the line between the eye and the insertion of the hind limb, and closer to the eye than to the tail (Inger 1966). The anus is dextral and does not reach the margin of the ventral fin (Inger 1966). The oral disc is ventral, subterminal, and about one-third of the body width (Inger 1966). Papillae are found in double, staggered rows along the margin of the lower lip and at the corners of the upper lip, with a gap in papillae at the center of the lower lip (Inger 1966). Labial teeth rows follow the formula 4(2-4)/3 or 5(2-5)/3 (Malkmus 2002). Tadpole beaks are strong, black, and denticulated, with the upper one pronouncedly convex at the center (Inger 1966).
Larvae are yellowish green above and silvery white below; the dorsal fin may also have golden dots (Malkmus 2002). Larvae acquire adult patterning on the body and hind limbs prior to eruption of fore limbs (Inger 1966). Malkmus (2002) notes that P. otilophus larvae are very similar to those of P. macrotis.
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Indonesia, Malaysia
Malaysian region distribution from AmphibiaWeb's database: Sabah, Sarawak
Polypedates otilophus is known from Kalimantan, Sabah, and Sarawak; it also occurs on Sumatra (Inger 1966). This tree frog primarily lives in secondary growth forest, at the edges of primary forest (Inger 1966), as well as in villages, tree plantations, logged areas, and other habitats modified by man (Malkmus 2002). It is a lowland species, occurring from sea level up to 500 m and rarely higher (Malkmus 2002), but apparently has also been recorded at up to 1000 m above sea level (IUCN 2006).
Life History, Abundance, Activity, and Special Behaviors
Polypedates otilophus is generally arboreal and is usually found on vegetation near pools of standing water (Inger and Stuebing 1997). A typical habitat at Kalabakan, Sabah, would be a logged area in which few tall trees remained, separated by a dense tangle of young secondary growth (Inger 1966). Males with nuptial pads call during the months of April, May, and June; ovulated females, foam nests, and larvae of various stages may be observed during the same period (Inger 1966). The full extent of the breeding season is not known (Inger 1966). Males call at night from low vegetation (generally under 2 m from the ground) near small temporary pools (Malkmus 2002). The call is a series of slurred, rasping notes followed by several loud "chucks" (Inger and Stuebing 1997). A call analysis is not available (Malkmus 2002). Females when clasped by males produce a foam nest, made by churning mucus with the hind limbs, which is attached to leaves of shrubs overhanging water (Inger and Stuebing 1997). After hatching the tadpoles wriggle free of the nest and, if the foam mass has not already fallen onto the pool's surface, drop into the water (Inger and Stuebing 1997). At hatching, larvae have fully developed eyes, external gills, open mouth, and oral suckers; labial teeth, papillae, and beaks are absent (Inger 1966). By the third day after hatching, the operculum has closed and oral suckers are still present (Inger 1966). On the fourth day, the first coil of the gut appears (Inger 1966). Beaks and labial papillae are present on the fifth day (Inger 1966).
Adults feed on a variety of insects and spiders (Malkmus 2002), especially large tree crickets (Inger and Stuebing 1997). This species is common (IUCN 2006) and has a distinctive, musty stench, which most people find offensive (Inger and Stuebing 1997).
Trends and Threats
Populations of this species are declining, but not significantly, due to a widely distributed and presumed large population, as well as the ability to tolerate some degree of habitat modification (IUCN 2006).
Relation to Humans
This species was once included in the pet trade (IUCN 2006), but is no longer due to its poor survival in captivity (Iskandar 2004).
Possible reasons for amphibian decline
General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
First described by Boulenger (1893), this species was originally given the name
Rhacophorus otilophus. It was renamed to Polypedates otilophus by
Boulenger, G. A. (1893). ''Descriptions of new reptiles and batrachians obtained in Borneo by Mr. A. Everett and Mr. C. Hose.'' Proceedings of the Zoological Society of London, 1893, 522-528.
IUCN, Conservation International, and NatureServe. (2006). Global Amphibian Assessment: Polypedates otilophus. www.globalamphibians.org. Accessed on 13 May 2008.
Inger, R. F. (1966). ''The systematics and zoogeography of the Amphibia of Borneo.'' Fieldiana Zoology, 52, 1-402.
Inger, R. F., and Stuebing, R. B. (1997). A Field Guide to the Frogs of Borneo. Natural History Publications (Borneo) Limited, Kota Kinabalu.
Iskandar, D. T. (2004). The Amphibians and Reptiles of Malinau Region, Bulungan Research Forest, East Kalimantan: Annotated checklist with notes on ecological preferences of the species and local utilization. Center for International Forestry Research, Bogor, Indonesia.
Liem, S.S. (1970). ''The morphology, systematics, and evolution of the Old World treefrogs (Rhacophoridae and Hyperoliidae).'' Fieldiana, Zoology, 57, 1-145.
Malkmus, R., Manthey, U., Vogel, G., Hoffmann, P., and Kosuch, J. (2002). Amphibians and Reptiles of Mount Kinabalu (North Borneo). Koeltz Scientific Books, Koenigstein, Germany.
Originally submitted by: Cindy Liu (first posted 2008-05-07)
Edited by: Kellie Whittaker (2014-10-29)
Species Account Citation: AmphibiaWeb 2014 Polypedates otilophus: File-Eared Tree Frog <https://amphibiaweb.org/species/4486> University of California, Berkeley, CA, USA. Accessed Jan 28, 2022.
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Citation: AmphibiaWeb. 2022. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 28 Jan 2022.
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