Thursday, September 25, 2014

A new burrow-using, fanged frog from Sarawak

Limnonectes cintalubang, new species (KUHE 47859)
Borneo is famous for its diverse endemic amphibians and the diversity can be expected to increase with the discovery of cryptic taxa. Frogs of the Limmnoectes kuhlii complex have enlarged head with fang-like processes on lower jaw in males, thus they are commonly called fanged frogs. Usually they have a brown dorsum covered by tubercles in variying degrees, and inhabit mountain streams at various altitudes. Limnonectes kuhlii was once considered a wide-ranging species, but is now regarded as a complex of many distinct species that are phylogenetically remote from Javanese L. kuhlii (Tschudi, 1838). Several continental populations have been described as distinct species, studies of Bornean populations have been lacking. Matsui et al. (2014) report finding a new species of this clade during a  recent amphibian survey in Serian, southwestern Sarawak. The frog has a unique coloration, escape behavior, and an unusual natural history.

The new species, Limnonectes cintalubang is subterranean and all specimens were found at night near burrows on the forest floor. When disturbed they immediately disappeared down the burrow. However, they do not seem to dig the hole by themselves, instead they use burrows constructed by other animals. What species dig the burrows used by this frog is unknown.  The skin of the species is exceptionally fragile and tears easily when captured. The eggs of L. cintalubang are creamy white unlike other congeners. Among Bornean frogs creamy white eggs without dark animal hemisphere are known in several  genera and all of them breed in deep shaded microhabitats such as small underground streams, in mud, and under leaf litter on the bottom of deep pools. The authors hypothesize that, L. cintalubang lays its eggs shaded localities, possible in water in the burrows.

Limnonectes cintalubang was found in loose slopes of secondary forests with mixed bamboo and broad-leaf trees, always on the ground. The surface of the ground is flat and sparsely covered by dead leaves, but with plant roots and stones densely packing the shallow layers under the soil surface. Frogs were active after 1930 h and each stayed near a burrow up to ca. 5–10 cm in diameter with a long tunnel at a depth of 50–60 cm, it was impossible to dig out the frog. Although only one of about 20 burrows observed had underground water, there was no pool at the immediate vicinity of the holes. The nearest water body was a stream ca. 8–12 m apart from the area. Males did not call in March, July, or December at the type locality. However, females collected in early July possessed large ovarian eggs, the breeding season is thought to include summer seasons. Other species found in association with the present new species in the forest were: Leptolalax gracilis (Günther, 1872), Leptolalax sp., Meristogenys jerboa (Günther, 1872), Nyctixalus pictus (Peters, 1871), and Polypedates leucomystax (Gravenhorst, 1829).

Matsui, M., Nishikawa, K., & Eto, K. (2014). A new burrow-utilising fanged frog from Sarawak, East Malaysia (Anura: Dicroglossidae). RAFFLES BULLETIN OF ZOOLOGY, 62, 679-687.

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