Phylogenetic position of the poorly known montane cascade frog Amolops monticola (Ranidae) and description of a new closely related species from Northeast India

ABSTRACT

The phylogenetic position of Amolops monticola, a cascade frog species known for over 150 years, remains unknown. Yet over the years new taxa have been frequently described in the ambiguously recognised A. monticola species group, based on morphology and presumed phylogenetic affinities. Here we report fresh collections of A. monticola from the Indian Himalayas and clarify its identity with new molecular and morphological evidence. Furthermore, our surveys in the Northeast Indian State of Arunachal Pradesh have led to the discovery of another new species in the A. monticola group from Siang River basin encompassing the Adi hills (historically known as Abor hills). The new species, formally described as Amolops adicola sp. nov., is morphologically distinguished from its congeners by a suite of characters that include adult size, body colouration and markings, skin texture, snout shape, foot webbing and digit tip morphology, in addition to significant morphometric distinctness observed in principal component analysis. Phylogenetically, the new species is recovered as a well-supported sister taxon of A. monticola, based on Bayesian and maximum likelihood inferences as well as Bayesian Poisson Tree Processes (bPTP) species delimitation analysis using 2001 bp of mitochondrial DNA (16S rRNA, cytochrome c oxidase subunit I and NADH dehydrogenase 2). It differs from other known members of the group by considerable genetic distances in the studied loci: ≥ 4.3% at 16S, ≥ 6.1% at COI and ≥ 7.0% at ND2. The study also shows for the first time the phylogenetic affinities of another Indian member of the A. monticola group, A. kohimaensis. Altogether, the new insights resolve the long-existing enigma surrounding A. monticola and facilitate a better understanding of systematic relationships within the large A. monticola species group. Our findings also emphasise the need for further dedicated studies on the cascade frogs of Northeast India.

KEYWORDS:

• Anura
• Amolops monticola species group
• Amolops kohimaensis
• bioacoustics
• Himalaya biodiversity hotspot
• integrative taxonomy
• redescription

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Author contributions

SDB, SG, AD and BLS conceived and designed the study; AD, NGP and SDB collected material in the field; SG, SDB and NGP generated data in the laboratory; SG, SDB, NGP and BLS analysed the data; SDB prepared figures and illustrations; SDB and SG wrote the manuscript draft; BLS, NGP and AD reviewed and edited the manuscript drafts; all authors approved the final draft.

Acknowledgements

The authors are grateful to the state forest departments for study permits to AD (Arunachal Pradesh: No. CWL/GEN/13(95)/11-12/Pt.V/438-40; Nagaland: No. CWL/GEN/96(vol-III)/550 and Sikkim: F.No. 78/GOS/FEWMD/BDR/APCCF52); Barry Clarke and David Gower (NHM, London), and Kailash Chandra and Kaushik Deuti (ZSI, Kolkata) for access to museum specimens and support to SDB; Robin Suyesh for support in call analysis; Bitupan Boruah for field work; and Sandra Goutte and Zhiyong Yuan for photographs of A. chunganensis (Figures 2(c) and 7) and A. wenshanensis (Figure 2(b)), respectively. AD is thankful to the Abor expedition team members Dhritiman Mukherjee, Manoj Nair, Bivash Pandav, Vivek Sarkar and Navendu Page. AD and NGP thank the Director, Dean, and S. Sathyakumar of the Wildlife Institute of India for support.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed here.

ZooBank registration

This published work and the nomenclatural acts it contains have been registered in ZooBank, the online registration system for the International Commission on Zoological Nomenclature (ICZN). The ZooBank LSIDs (Life Science Identifiers) can be resolved and the associate information can be viewed through any standard web browser by appending the LSID to the prefix http.//zoobank.org. The LSID for this publication is urn:lsid:zoobank.org:pub:B2BEB68E-EE55-4FD8-91BB-E71A8CEAD319. The LSID for the new species is urn:lsid:zoobank.org:act:9968D3D8-9846-4BF5-8CA2-AE0CF5DE71EC.

Additional information

Funding

This research was partially supported by the following funding: Hem Chand Mahindra Foundation’s financial support to AD for undertaking the Abor expedition; DST-NMSHE Grant (DST Grant Number: DST/SPLICE/CCP/NMSHE/TF-2/WII/2014[G]) from the Department of Science and Technology, Government of India, to AD and NGP for undertaking field work in Sikkim; DU-DST Purse Grant from the Department of Science and Technology, Government of India, to SDB; CSIR-Research Associateship [CSIR No. 09/045(1694)/2019-EMR-I] from the Council of Scientific and Industrial Research, Government of India to SG.