A paper describing 12 new frog species, and reporting three rare species thought to have been extinct, has been published in the international taxonomic journal Zootaxa by Indian zoologists led by S. Das Biju of the University of Delhi.
The discovery of these new and rare species was facilitated by the distinct and unique voices or calls of the male frogs.
In effect, these calls alerted the scientists to the fact that the calls could indicate new species of frogs.
Based on the structure and other features of the calls, the populations of these frogs were confirmed to belong to new species, and were described as such by the research team of S. Das Biju.
Biju says there are now 336 species of frogs in India, but thinks that this number is only half of what exists in the wild.
As far as I know, the recognition of new frog species mainly on the basis of the calls of the males (females do not call) has been made as early as the early 1990s.
Walter C. Brown, Arvin Diesmos and I described five new species of forest frogs (genus Platymantis) from the Mount Maquiling and Mount Banahao areas on Luzon Island. The papers describing these species were published by the California Academy of Sciences, San Francisco, California.
One of these species had been confused with the well-known species of the genus for a long time, until we showed through its advertisement calls that it was a distinct speciesnot by its appearance but by its calls as heard by the human ear, and as analyzed with a sonograph.
From that time on, recording of calls as a diagnostic feature of frog species has become a routine procedure for our taxonomic work on Philippine frogs, which could reach up to 150 species from the present 107 known species.
Frog calls are now included in the formal description of frog species.
A search of the literature on frog calls showed that calls have ecological functions as interpreted by frog specialists. But none of the papers reviewed so far talks about the taxonomic application of the studies on frog calls.
Our earlier work showed the usefulness of frog calls in distinguishing different species long before the work of Indian zoologists described above.
Further research on frog calls are needed to determine the individual variations of calls of a population of a species. It is important to know whether there are “dialects” of subgroups found in different areas of a species’ range.
In birds, experiments have shown the existence of these dialects in crows, as demonstrated by the failure of a subgroup to react to a warning call of another subgroup. Ornithologists have used bird calls to identify species in the wild for some time.
