Guwahati: Over ninety-six amphibian species are in Arunachal Pradesh but there are still many who are hopping and crawling in its diverse and unique habitats.
All this has been documented in the study “Fauna of Eastern Himalayas- Amphibians of Arunachal Pradesh” by Bikramjit Sinha and Bhaskar Saikia of Zoological Survey of India, which is an updated inventory of amphibian diversity of Arunachal Pradesh collating existing information on amphibian diversity of the state and also highlighting the potential gap areas.
The book was released during the inaugural function of the Research Advisory Monitoring Committee(RAMC) meeting of ZSI held in the Shillong Centre of ZSI recently.
It was released by Nameeta Prasad, Joint Secretary, MoEFCC, New Delhi; Dr. S. C. Gairola, former PCCF and HoFF, Maharastra and chairman of RAMC of ZSI, in the presence of ZSI Director Dr. Dhriti Banerjee and other dignitaries.
Amphibians are frogs, toads, newts, and salamanders.
After the Western Ghats, Northeast India, including Arunachal Pradesh, is known as the major centre of amphibian biodiversity of the Indian subcontinent.
The authors say amphibian diversity in this biodiversity-rich area has remained under-explored and unexplored due to the inaccessibility of difficult hilly terrain, lack of communication network, and similar other reasons. Of late, however, there has been some good news, thanks largely to the untiring efforts of dedicated herpetologists from the region as well as the country.
However, this entire information lies scattered in individual reports. “Our study is a sincere effort to collate the existing information on amphibian biodiversity of Arunachal Pradesh, and also to highlight the potential gap areas,” the authors say.
Arunachal Pradesh lies in one of the 35 biodiversity hotspots of the world, the Eastern Himalayas, and is uniquely situated in the transition zone between the Eastern Himalayas and Indo-Burmese biodiversity hotspots, Palearctic and Oriental biogeographic region, and the Himalayas and Peninsular India.
The current amphibian diversity of Arunachal Pradesh stands at 96 species under 38 genera, 10 families, and all the 3 living orders.
A two-year research study was undertaken by scientists from ZSI from April 2016 to 2018, in which more than 100 localities in 28 locations spread across 8 districts were surveyed.
Some of the protected areas covered during the study period are Itanagar Wildlife Sanctuary, Tale Wildlife Sanctuary, Mehao Wildlife Sanctuary, and Pakke Tiger Reserve. Different typical ecosystems like grasslands, tropical to temperate forests, alpine areas and high-altitude lakes were also surveyed during the study.
Interestingly, 25 out of the 96 species are endemic to Arunachal Pradesh and in the state, the highest endemicity was found in the Lower Subansiri district.
“The most abundant area in terms of amphibian diversity richness, among our study areas, is Lower Subansiri District, with 25 species collected by the authors during the course of the study. This only reiterates that a whole lot of interesting amphibian fauna is hopping and crawling in the diverse and unique habitats of this Himalayan state, which are yet to be recorded,” the study says.
Even the second record of endemic species such as Polypedales subansiriensis and Rhacophorus subansiriensis as reported in this study after their description way back in 2009 is also recorded in the same district, more specifically from a 10 sq. km area of the type locality in the Apatani Plateau of Ziro Valley. The next highest endemicity of three species was found in the Namdapha Tiger Reserve of Changlang district.
From the conservation context, the amphibians of the state are represented by one endangered species (Xenophrys medogensis), one nearly threatened species (Nanorana annandalii), four vulnerable species (Amolops anigiaoensis, Ingerana borealis, Pterorana khare, and Theloderma moloch), 37 species are categorized under the least concern category of which four species are endemic to India. The conservation status of the rest of the species is either not evaluated (26 spp.) or data deficient (20 spp.).
Out of the 26 not evaluated species, 16 species are either endemic to India or North-east or Arunachal Pradesh or a particular area like Tale Wildlife Sanctuary and Namdapha Tiger Reserve. Further, out of 20 data-deficient species, six are endemic to the region. Ironically some of these have not been evaluated or are data deficient but endemic species such as Philautus kempii, Kurixalus naso, Nanorana gammii, and similar others have been described more than 100 years ago. However, till now we do not have any clue about their population status.
This perhaps indicates a future potential area of research in amphibians of the state. The evaluation of the endemic species, particularly those restricted to a particular area like Polypedates subansiriensis and Rhacophorus subansiriensis, needs immediate attention as their critical habitats are under severe threat from rapid urbanisation and modernisation.
Besides these interesting observations, we are of the opinion that there are vast areas of the State, yet to be surveyed thoroughly vis-a-vis amphibian study. The higher reaches of the Himalayas stretched along the entire length of the state are yet to be surveyed for studying their faunal elements.
During the course of our study, the authors have observed that the upper reaches of the Eastern Himalayas of the State (except Tawang, Upper Subansiri, Upper Siang, and Upper Dibang Valley districts) are hardly represented in our data. “Very little is known about the amphibian diversity from these areas. Correspondingly, that is also true of the altitudinal distribution of amphibians above 2500 m, where very little information could be gathered by the authors. This study helps us in identifying the gap areas as far as amphibian research is concerned,” the study says.
“During the course of this study, we have come across a number of specimens that could potentially be new to science. We hope that further studies on these specimens will lead to the description of new species. In this regard, the present list of species in this book will result in an upward revision in the near future,” Bhaskar Saikia, one of the authors, told EastMojo.
The scientists say, “What has been documented during the course of this current study is the tip of the iceberg. With the limited number of surveys and the studies on the backlog collections, these have resulted in many new species, new country and state records.”
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