Friday, January 27, 2023

[Herpetology • 2023] Litoria hastula • A New Species of Torrent-breeding Treefrog (Anura: Pelodryadidae) from the mountains of Papua, Indonesia, with New Records and Observations of Litoria dorsivena (Tyler, 1968)

Litoria hastula 
Oliver, Iskandar & Richards, 2023

photographs by S.J. Richards.

The mountains of New Guinea are home to species-rich but poorly understood communities of stream or torrent-breeding pelodryadid treefrogs. Here we describe a new species of moderately sized torrent-breeding Litoria from the mountains of Papua Province, Indonesia. The new species is most similar to Litoria dorsivena but differs from that species in aspects of body size, skin texture and especially the shape of the snout. Based on recent collections, we also present new data on the distribution and colour in life of L. dorsivena. Both species show marked sexual size dimorphism when compared to most other pelodryadid treefrogs, and the colour pattern of the new species may also vary between males and females. The torrent-breeding treefrogs of New Guinea remain poorly known and, given declines of ecologically similar pelodryadids in Australia, should be a priority group for taxonomic research and population monitoring.

Keywords: Cryptic extinction risk, New Guinea, sexual size dimorphism, taxonomy

Colouration of Litoria hastula sp. nov. in life:
A lateral view of adult male paratype SAMA R72334; B hidden coloration in thighs of male paratype SAMA R72335; C lateral view of adult female paratype MZB Amph.32872; D ventral view of adult female paratype MZB Amph.32872.
All photographs by S.J. Richards.

Litoria hastula sp. nov.

Diagnosis: A species of Litoria that can be distinguished from all congeners by the following unique combination of characters: moderate size and strong sexual size dimorphism (4 adult males 30.4–31.8 mm SVL, one adult female 48.9 mm SVL); snout moderately long (EN/IN 0.69–0.80), with sharply acuminate tip and with concave dorsal surface; canthus rostralis nearly straight, sharply defined; limbs moderately long (TL/SVL 0.55–0.60); finger webbing moderate, not extending beyond third phalanx between Finger 3 and Finger 4; toe webbing extensive, extending to penultimate phalanx between all digits except Toe 1 and Toe 2; dorsal skin relatively smooth with scattered small tubercles; heel with 2–3 distinct conical tubercles; vomeropalatines prominent; vocal slits present in males; dorsal colouration predominately light to mid-brown with scattered darker-brown spots and or blotches; venter largely buff with little to no pattern; and advertisement calls produced in series of 5–7 calls, each comprising a single short note that is unpulsed or slightly pulsatile but may become longer, with discrete pulses, in terminal calls of the series.

Etymology: Latin, “little spear’, combining spear hasta” with the diminutive suffix “-ula” in reference to the elongate and sharply pointed snout of the species.

Details of habitat at the type locality for Litoria hastula sp. nov.:
 A dense and very mossy mid-montane forest, and B small fast-flowing rocky stream. The type series was collected from low vegetation along this stream at night.
 All photographs by S.J. Richards.

Paul M. Oliver, Djoko T. Iskandar and Stephen J. Richards. 2023. A New Species of Torrent-breeding Treefrog (Pelodryadidae: Litoria) from the mountains of Papua, Indonesia, with New Records and Observations of Litoria dorsivena (Tyler, 1968). Vertebrate Zoology. 73: 127-139. DOI: 10.3897/vz.73.e91111