Description
Rhacophorus vampyrus, also known as the vampire treefrog, has a snout-vent length range for males of 42.5 - 44.8 mm and females of 38.9 - 53.4 mm. The head length is almost equal to the head width and the head is slightly wider than the width of the body. The pupils are horizontally elongated and the snout is truncated. The tympanum is barely visible externally and they have a weak supratympanic fold. The body is dorsoventrally compressed and the forelimbs are relatively robust and the hindlimbs are long and slender. The dorsal skin is smooth, the ventral surface of thighs and belly is coarsely granular, and the chest and throat is smooth. The tips of the digits are expanded into well developed large disks that bearing circummarginal grooves. The disks are relatively wide compared to the finger widths. The tips of the toes also have well developed disks with distinct circummarginal grooves but the disks are smaller than those of the fingers. There is moderate webbing between the fingers and toes, although not as extensively as in other Rhacophorids. The relative length of the fingers follows the following pattern: I < II < IV < III and the toes: I < II < III < V < IV. The males have external paired subgular vocal sacs but nuptial pads are absent. There is a pointed projection present at the tibiotarsal articulation, which is approximately 1 mm long (Rowley et al. 2010).

Rhacophorus vampyrus has several morphological features that distinguish it from other Rhacophorid species in the Southeast Asia region. This species has a pale tan to brick red dorsum, white throat, chest and belly, the flanks, anterior and posterior surface of thighs are mostly black, grey to black webbing between the fingers and toes, reduced finger webbing and pointed projections at the tibiotarsal articulations. The most notable attribute that sets this species apart is the unique morphology of the tadpole mouthparts, which bear a pair of keratinized hooks, resembling “fangs”, unseen in any other frog species to date (Rowley et al. 2010).

The dorsal surface of Rhacophorus vampyrus is pale copper-brown with faint darker brown mottling along the back of the frog. The dorsolateral surfaces contain very small, sparse, white and darker brown flecks. The dorsal surface of the lower arms, thigh and tibiotarsus are copper-brown with widespread darker brown barring. The dorsal surface of the hands and feet are copper-brown proximally, fading distally to pinkish-cream on the fingers and toes I-II, and grey on fingers III-IV and toes III-V. There is dark grey to black webbing dorsally. The flanks, upper arms, ventral surface of lower arms, anterior and posterior surface of thighs, and ventral surface of crus are black, and there are small irregular white spots within the black coloration on the flanks and upper arms. The ventral surface of the throat, chest and belly are immaculately white except for black mottling extending slightly onto the lateral margins of the chest at the axilla. The ventral surfaces of the toes and fingers are pale grey. The ventral surface of the webbing is grey with dark grey-black margins. The dorsal coloration of this species varies from pale tan (diurnally) to brick red (nocturnally). The iris is pale yellowish gold with a network of fine dark gold reticulations concentrated around the pupil. The color of this species in preservative is the same as in life, but with the dorsum fading to pale tan (Rowley et al. 2010).

In life, metamorphs are yellowish (Vassilieva et al. 2013).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Viet Nam

View distribution map in BerkeleyMapper.

Distributed in the Langbian Plateau in southern Vietnam. This frog inhabits montane moist evergreen forest between 1470 – 2004 m elevation at Bidoup-Nui Ba National Park in southern Vietnam (Rowley et al. 2010).

Life History, Abundance, Activity, and Special Behaviors
Rhacophorus vampyrus is an arboreal adapted tree frog, capable of gliding by utilizing the webbing between the fingers and toes. This species is oviparous and the embryos develop into a free-living tadpole stage (Rowley et al. 2012).

Reproduction occurs from May to July, during the rainy season. At the time of the species description, males calls and amplexus had not been observed (Rowley et al. 2012).

Adults of this species are phytotelm breeders that deposit foam nests in small tree-holes, located away from streams or ponds. Nests are generally 30 - 120 cm above the ground. They produce clutches of up to 250 eggs. As of 2013, R. vampyrus was the only known Rhacophorus that was known to breed and raise its offspring in tree hollows (Rowley et al. 2012; Vassilieva et al. 2013).

Some form of parental care has been observed as females are known to deposit trophic eggs into the nest to feed young and a male was seen near one nest site on multiple nights (Rowley et al. 2012).

As of 2013, feeding habits in adults have not been reported (Rowley et al. 2012).

Larva
Rhacophorus vampyrus tadpoles at Gosner stage 27 has a total length range of 16.2 - 20.0 mm, a body length range of 3.8 - 6.2 mm, and a tail length range of 11.7 - 14.4 mm. At Gosner stage 34, their total length range is 28.8 - 34.0 mm, body length range is 7.3 - 9.5 mm, and tail length range is 19.8 - 24.6 mm. They have an elongated, depressed body. The small eyes and nostrils are located dorsally, closer to the snout then eye. The snout is depressed dorsoventrally and truncated. The small, prominent nostrils are oval and project dorsolaterally. Neuromasts can be found near the snout and on the ventrolateral surface of the head. The internarial distance is slightly larger than the interorbital distance. The eyes are small, elliptical, and located dorsally with anteriolaterally oriented pupils. The upper edges of the orbits are prominent. The oral disc is anteriorly located, greatly reduced, and non-emarginated. The mouthpart change around Gosner stages 25 - 26 (see below for a full description). However, at stage 27, the upper labium is reduced to one large papilla-like structure on each side, and the upper jaw sheath bears a few huge, widely spaced, hook-shaped serrations that face backwards into the buccal cavity. A lower jaw sheath is absent. Instead there are two large forward facing, keratinized hooks resembling “fangs,” which are bordered laterally by two fleshy papillae on the margin of a reduced lower labium. The tubular, sinistral spiracle is located ventrolaterally at the mid-body, and has a small, hidden, oval opening that is most often only visible from the ventral view. The medial vent tube is a long and narrow with its opening at the base of the tail. The laterally compressed tail has a length that is about 3 times that of the body length, and a pointed tip without a terminal filament. At the base, the muscle width is slightly more than half the height. While the fins are low, the total tail height is above the body. The upper fin is taller than the lower fin. The upper fin starts from the base of the tail, and both fins run parallel to the tail tip (Rowley et al. 2012, Vassilieva et al. 2013).

The mouth parts of the tadpole change at Gosner stages 25 - 27. At stage 24 and 25, the upper jaw appears as a horny arch with 14 - 15 conical serrations that curve toward the mouth. The early fangs appears as two keratinized round crests with 2 - 3 serrations that point dorsally. However the shape of these lower jaw elements varied. In the later 25th stage and into the 26th stage, the upper jaw disappears, sometimes replaced by widely-spaced denticles. The paired keratinized crests, where the lower jaw would normal be, develops into conical denticles. During stage 27 the upper jaw denticles increase in number to 9 - 11 and the base of the denticles enlarge and fuse to form new serrated upper jaw arch. The fangs continue to grown into their ultimate shape. The mouth parts disappear again at stages 41 - 42 (Vassilieva et al. 2013).

Coloration:

In life, the body is uniformly dark brownish grey to medium brown, caused by dark melanophores. The tail and fins are considerably paler than the body - unpigmented in early development and medium slate grey or medium brown at later stages. The keratinized most parts are black. The irises are black with silvery or golden iridophores that are especially dense near the rim of the pupil. Preserved tadpoles are uniformly black (Rowley et al. 2012; Vassilieva et al. 2013).

The species is unique among Rhacophorus because its tadpoles and early-stage metamorphs have fangs and are oophagus (Rowley et al. 2012, Vassilieva et al. 2013).

During the rainy season between May - July 2010, eight foam nests and/or groups of tadpoles were observed, all in water filled tree-holes, 0.3 - 1.2 m above the ground. In nests containing tadpoles or metamorphs, there have been up to 10 individuals observed per tree hole (Rowley et al. 2012).

The length of development from oviposition to hatching and the length of time required for metamorphosis is unclear as tadpoles from many developmental stages have been found in the same tree hollow. Two possible explanations are that there are different developmental times given access to food or multiple clutches were laid in the same hollow (Vassilieva et al. 2013).

Adult female has been observed ovipositing trophic eggs to tadpoles and eggs have been retrieved from the guts of tadpoles, confirming that they are oophagous during the larval stage. It is hypothesized that the fang hooks assist in slicing open unfertilized eggs prior to consumption (Rowley et al. 2012; Vassilieva et al. 2013). The tadpoles do not appear to feed on any alternative foodstuffs (Vassilieva et al. 2013).

Comments

Etymology

References

Rowley, J.J.L, Duong, L.T.T, Dao, T. A., Stuart, B.L., Huy, H.D. 2010. A new tree frog of the genus Rhacophorus (Anura: Rhacophoridae) from southern Vietnam. Zootaxa 2727: 45-55. [link]

Rowley, J.J.L.,Tran, D.T.A., Le, D.T.T., Hoang, H.D., Altig, R. 2012. The strangest tadpole: the oophagous, tree-hole dwelling tadpole of Rhacophorus vampyrus (Anura: Rhacophoridae) from Vietnam. Journal of Natural History Vol. 46, Nos. 47-48, 2969-2978. [link]

Vassilieva, A. B., Galoyan, E. A., Poyarkov, N. A. (2013). "Rhacophorus vampyrus (Anura: Rhacophoridae) reproductive biology: a new type of oophagous tadpole in Asian treefrogs." Journal of Herpetology, 47(4), 607-614. [link]

Species Account Citation: AmphibiaWeb 2024 Rhacophorus vampyrus: Vampire Flying Frog <https://amphibiaweb.org/species/7611> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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