Description
Rhacophorus vampyrus is a recently discovered vampire treefrog with a snout-vent length 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).

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.

Reproduction occurs from July to May. 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. 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. The length of development from oviposition to hatching and the length of time required for metamorphosis to occur have not yet been observed. It is unknown if there exists parental care by the males, the females or both. In nests containing tadpoles or metamorphs, there have been up to 10 individuals observed per tree hole. It is currently unknown if the males call but according to Rowley et al. (2012), a male was seen near one nest site on multiple nights. The mode of amplexus is currently unknown as well. Feeding habits in adults have not been observed but an 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 (Rowley et al. 2012; Vassilieva et al. 2014).

The species is unique among Rhacophorus because its tadpoles and early-stage metamorphs are oophagus and females are known to deposit trophic eggs into the nest to feed young (Rowley et al. 2012, Vassilieva et al. 2014). The tadpoles do not appear to feed on any alternative foodstuffs (Vassilieva et al. 2014).

Larva
Rhacophorus vampyrus tadpoles are 32.8 mm in total length at stage 35 of development. They have an elongate, depressed body, with a tail length that is about 3 times that of the body length, and the tail fin is about as tall as the body and contains a slightly pointed tip. The small eyes and nostrils are located dorsally. They have a sinistral spiracle that is only visible ventrally and they have a long, narrow, medial vent tube. They have a greatly reduced, non-emarginated oral disc, 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 and two large forward facing, keratinized hooks resembling “fangs” which are bordered laterally by two fleshy papillae on the margin of a reduced lower labium (Rowley et al. 2012).

These tadpoles are oophagous and it is hypothesized that these hooks assist in slicing open unfertilized eggs prior to consumption. The morphology of the tadpole gills is currently unknown because no tadpoles at an early stage of development have yet been observed. In life, the body is uniformly dark brownish grey to medium brown with the tail and fins considerably paler than the body. Preserved tadpoles are uniformly black (Rowley et al. 2012; Vassilieva et al. 2014).

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.

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.

Species Account Citation: AmphibiaWeb 2022 Rhacophorus vampyrus: Vampire Flying Frog <https://amphibiaweb.org/species/7611> University of California, Berkeley, CA, USA. Accessed Sep 26, 2023.

Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 26 Sep 2023.

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