New species of bird-eating frog discovered in Thailand.
July 2008. The newly recognised frog, known as Limnonectes megastomias has only been found in three remote locations in Thailand. While similar in appearance to other members of the Limnonectes "kuhlii" group, there are several morphological and genetic differences that validate this new discovery.L.megastomias appears to be an aquatic frog that inhabits reliable, year round, streams. The frog has so far been found at medium to high altitudes (600-1500 metres) at Sakaerat Environmental Research Station (SERS), and in Pang Si Da National Park and in the Phu Luang Wildlife Sanctuary.
Appearance
The new frog has a greatly enlarged head and enlarged "fangs" within its mouth. The males of this species have exceptionally large mouths and powerful jaws that appear to be out of proportion with the rest of the animal. Unlike many other species of frogs, the males are larger than the females, at least their heads are larger. The body remains about the same size as in females, but the head continues to grow and gets considerably larger than the females. It certainly gives the appearance that the male is a much larger frog.
David Mcleod writes
The "fangs" are actually odontoid processes. These are outgrowths of the mandible and are found in several members of the genus Limnonectes. Odontoids vary in size and shape in this genus. Some researchers have indicated that males use fangs in male-male combat situations (see Tsuji and Mastui 2002, Journal of Herpetology. 36:3). In L. megastomias I have not directly observe male-male combat, but did observe missing limbs, and scars on limbs that would indicate that males of this species may be engaging in this behavior. The odontoids of L. megastomias are large (4-5 mm in large males), broad, and blunt tipped and they scale with the increased size/maturity of the frog. Odontoids are present in females, but are quite small (1-2 mm in height) as they are in juveniles as well. In some species from the Philippines (e.g. L. macrocephalus) the odontoids are narrower and more "fang" like.
Unusual diet
Limnonectes megastomias is known to consume insects, other frogs, and birds. David Mcleod has been studying the "bird eating", identifying the bird species and other elements of this frog's diet. The feathers of a bird were discovered in the faeces of a batch of frogs he was holding in captivity for a couple of days. These frogs are often observed in the water near the stream bank. It would seem that they sit and wait for prey to come along and then eat opportunistically.
Discovered in a well studied zone
The exciting thing about this discovery is that the research station (SERS) the frog was first found at has been well studied for more than 40 years. It just happened that this frog was living in a very isolated part of the protected study area. Not long after David Mcleod found this frog, two of his colleagues found similar specimens at two nearby locations. It is exciting to realize that in a country (and at a field station) as well studied as Thailand (and SERS), that there are still new taxa being discovered, even relatively large animals like this frog. There is a lot that we don't know about L. megastomias and other closely related frogs in terms of their natural history, reproductive biology, and other aspects of their ecology. We don't know if populations of these frogs are stable or in decline. We just don't know enough about them yet.
Unusually, the males are larger than the females, et least their heads are larger . . . The body remains about the same size as in females, but the head continues to grow and gets considerably larger than the females. It certainly gives the appearance that the male is a much larger frog.
Courtesy of
David S. McLeod
Department of Ecology and Evolutionary Biology, and Natural History
Museum & Biodiversity Research Center
University of Kansas
The full scientific paper was published in Zootaxa.
