New genus of tree frog found in Andaman Islands and Northeast India
A team of Indian, Indonesian, Chinese and Thai researchers led by Prof SD Biju of University of Delhi has found a new genus of the Old world tree frog family Rhacophoridae. The new genus Rohanixalus is named after the Sri Lankan taxonomist Rohan Pethiyagoda. The findings were published in the article titled ‘New insights on the systematics and reproductive behaviour in tree frogs of the genus Feihyla, with description of a new related genus from Asia (Anura, Rhacophoridae)’ in the current issue (12 November 2020) of Zootaxa, an international journal of animal systematics.
The scientists studied multiple aspects, such as the external morphology of adults and tadpoles, phylogeny, calls, and breeding biology of several tree frog species widely distributed across South, Southeast, and East Asia and confirmed that they represent a new genus. Frogs of this genus are known to inhabit forested as well as human-dominated landscapes right from Northeast India, Andaman Islands, Myanmar, Thailand, Malaysia, Indonesia, Vietnam, Laos, and Cambodia, up to southern China. Rohanixalus is the 20th recognized genus of the family Rhacophoridae and currently comprises eight out of the 422 known Old World tree frog species found in Asia and Africa.
Frogs of the new genus are characterized by a rather small and slender body (size about 2 to 3 cm long), a pair of contrastingly colored lateral lines on either side of the body, minute brown speckles scattered throughout the upper body surfaces, light green colored eggs laid in arboreal bubble-nests, and several unique behavioral traits including maternal egg attendance. Based on DNA studies, the new genus is also revealed to be a distinct evolutionary lineage from all previously known tree frog genera. During the breeding season, these tiny reddish-brown frogs can be found in large aggregations on bushes and shrubs (about 1 to 4 meters high) surrounding water bodies. Scientists believe that many more unnamed Rohanixalus species are likely to be present and future dedicated efforts are required to fully understand the existing species diversity in this new genus.
This is the first time a tree frog species, Rohanixalus vittatus (Striped Bubble-nest frog), is reported from the Andaman Islands of India. Even though the amphibian fauna of Andamans has been frequently surveyed in the recent years, this frog was so far not reported, despite being commonly found in wayside areas of North and Middle Andaman Islands. New findings, such as this frog, indicate that the amphibian inventory of the region is still far from being complete.
“Our discovery of a treefrog member from Andaman Islands is unexpected and once again highlights the importance of dedicated faunal surveys and explorations for proper documentation of biodiversity in a mega diverse country like India. This finding also uncovers an interesting new distribution pattern of tree frogs that provides evidence for faunal exchange between Andamans and the Indo-Burma region” said Prof. SD Biju.