Description
Litoria hilli is a medium sized frog, with females larger than males (53.8-54.7mm SVL in females vs. 43.6-49.4mm in males). This frog has fully webbed hands and a snout terminating in a distinct fleshy rostral spike (in both males and females). Eyes are large and protuberant with wide eyelids. The nostrils run closer to the tip of snout than to the eyes. A row of low pustules is found along the margin of the mandible. Two patches of vomerine teeth are present. A tympanic ring is present but covered posterodorsally by a supratympanic skin fold. Hands are fully webbed, with finger length decreasing from 3>4>2>1. Fingertips are flattened into discs that possess circummarginal grooves, and discs are two times wider than the penultimate phalanges on the fingers. Hind legs are moderately long (TL/SVL = 0.50), and toes decrease in length 4>5=3>2>1. All toes are webbed up to the discs, and the discs have distinct circummarginal grooves. The inner metatarsal tubercle is present, but the outer metatarsal tubercle is weakly developed. Skin of dorsal surfaces looks finely granular, with many pustules; ventrum and thigh appear coarsely granular; and anterior portion of thighs and arms are smooth. Below the anus are two dermal flaps surrounded by many pustules. Lateral margins of hands, forearms, feet, and tarsi have crenelated dermal ridges. Pustules are also present on heels and along margin of mandible. In males, nuptial pads bear brown dermal asperities that continue from the wrist to the center of the subarticular tubercle of a hypertrophied Finger I. Males also have relatively larger eyes, a shorter snout, and a longer rostral spike, as well as a vocal sac (Kraus 2007).

In life, the dorsum shows a mixture of yellow-brown, olive-green, and red-brown, with yellow-brown pustules. Specimens may also be more olive-green with indistinct purplish-brown markings, or darker brown with pustules less evident. The posterior surfaces of the thigh, groin, and feet are colored brown-purple. Many white pustules are present on the ventral surfaces of the thighs, and the groin area. The chin, chest, and anterior part of the belly are white. The posterior belly is purplish-brown with white granules, and white pustules surround the anus. A few dark purple flecks are found on the jaw margin. The iris of the eye is tan (Kraus 2007).

In preservative, Litoria hilli appears brown on dorsal surfaces, and retains the white patterns on limbs, chest, and abdomen. Hands and feet have prominent purple-brown pigmentation and the iris looks pale, silvery white (Kraus 2007).

This species of tree frog is readily distinguishable from most other Papuan species of the genus Litoria (except L. prora and L. humboldtorum) in having fully webbed hands and a fleshy rostral spike in both sexes. Litoria hilli differs from these species by its larger size, reduced crenelated fringes on arms and legs, absence of heel lappets, brown-green color pattern, low (vs. well-developed) row of pustules on the jaw margin, and having a tan iris (Kraus 2007).

The tadpole has a depressed and elongated body. Snout is rounded, acutely in lateral view and more broadly in dorsal view. Nares are small and directed anteroventrally. Eyes are dorsolateral and oriented laterally. Oral disc of older tadpoles has marginal papillae in unbroken rows (1-2 anterolateral rows, 2-3 lateral rows, 2-4 posterior rows) and lateral submarginal papillae, and is not emarginate. Labial tooth row formula 2(2)/3, with a small A2 gap. Strongly keratinized, serrated jaw sheaths, with that of the upper jaw slightly curved and that of the lower jaw slightly V-shaped. Tadpole mouthparts are identical to those of L. humboldtorum. Spiracle sinistral and ventrolateral. Vent tube is lacking, with the cloacal aperture flush with the posterior body wall except for the slightly protruding swollen margins of the cloaca. Tails are long and have high fins (Kraus 2007).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Papua New Guinea

View distribution map in BerkeleyMapper.

This species is apparently endemic to a single island in the Louisiade Archipelago, off the southeastern tip of Papua New Guinea. Litoria hilli has been found only on Sudest Island, on the western slopes of Mt. Rio from 130-410m asl; surveys on nearby Louisiade islands (Rossel and Misima) did not find this species. The distribution extends across most of Sudest Island in lowland rainforest areas, but not above 600m where cloud forest predominates. Most specimens of Litoria hilli were collected around the margins of a muddy pond along the shallow, slow-flowing Gesirava River, in primary lowland rainforest. Local inhabitants have also reported observing this species in sago swamps and other areas with standing water, including water-filled pig wallows (isolated from other sources of water) on ridges up to 410m asl (Kraus 2007).

Life History, Abundance, Activity, and Special Behaviors
Adults perch on the upper surfaces of leaves about 1.5–2.5 m above ground, mostly at night but occasionally during the day (Kraus 2007).

Litoria hilli lays its eggs on leaves overhanging small pools. Clutches consist of gelatinous egg masses of 4-46 individual eggs, with each egg encased in a single-layer capsule. Tadpoles were collected from a pig wallow on a ridge at 240m asl on Sudest Island (Kraus 2007).

Comments
The name honors the author of "Cyrano de Bergerac," Edmond Rostand, because of his interest in long-snouted life forms; here the long snout refers to the fleshy rostral spike present on L. rostandi (Kraus 2007).

References

Kraus, F. (2007). ''A new species of treefrog of the genus Litoria (Hylidae) from the Louisiade Islands, Papua New Guinea.'' Herpetologica, 63, 365-374.

Species Account Citation: AmphibiaWeb 2014 Litoria hilli <https://amphibiaweb.org/species/6988> University of California, Berkeley, CA, USA. Accessed Dec 2, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 2 Dec 2024.

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