Shedding light on taxonomic chaos: Diversity and distribution of South Asian skipper frogs (Anura, Dicroglossidae, Euphlyctis)

Abstract

A known haven of amphibian diversity, South Asia is also a hotspot of taxonomic confusions. Vastly distributed from Saudi Arabia to Myanmar, the dicroglossid genus Euphlyctis (“skittering” or “skipper” frogs) is a representative example. Combining phylogenetic analyses with 16S barcoding and genome size variation of 403 frogs from 136 localities, we examined genetic diversity and distributions across the whole range of Euphlyctis, with a particular focus on taxonomic and nomenclatural issues. We recovered two deeply divergent mitochondrial clades totalling ten lineages that we considered as species, and eight could be attributed valid taxonomic names and junior synonyms. The first clade (subgenus Phrynoderma) is confirmed in South India, Bangladesh and Sri Lanka, and comprises six species: E. karaavali, E. hexadactyla, E. aloysii, E. kerala and two undescribed taxa. Five are endemic to the Western Ghats biodiversity hotspot and four of them form the E. aloysii species complex. The second clade (subgenus Euphlyctis) extends across South Asia and neighbouring regions, and comprises four species: E. ehrenbergii, E. jaladhara, and two widespread lineages erroneously called “E. mudigere” and “E. kalasgramensis” in recent literature, while their oldest valid names appear to be E. cyanophlyctis and E. adolfi, respectively. Additional analyses on this pair of taxa highlighted strong phenotypic resemblance, notable intraspecific phylogeographic structure, and an extensive contact zone along the southern slopes of the Himalaya, with putative signs of genetic introgression. Through an independent investigation of the historical literature, we identified overlooked issues and misconceptions regarding the status of many old and recent taxa, and proposed solutions, such as transferring “E. ghoshi” to the genus Limnonectes. Our study illustrates how range-wide genetic barcoding can clarify taxonomic confusions, and we call to solve remaining issues prior to the description of new taxa.

Key words:

• Euphlyctis adolfi
• Euphlyctis cyanophlyctis
• genetic barcoding
• genome size
• phylogeography
• systematics
• Phrynoderma
• taxonomy
• Western Ghats biodiversity hotspot

Acknowledgments

This study was only possible thanks to the key contribution of Ukrainian PhD candidate G Mazepa, who declined authorship, and we dedicate this paper to him. We are also grateful to J Polaková for her help with the lab work; J Streicher (NHMUK [BMNH]), G Ramakrishna, BHCK Murthy and K Deuti (ZSI) for granting access to collections and curatorial assistance during the visits of SM; R. Khot (BNHS) for accessioning RGK specimens; K. Sunagar and P. Karanth (Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, Karnataka, India) for molecular lab facilities and lab support to RGK; D. Kamei and T. Sangma for assistance in the field to RGK. Fieldwork and specimen collection permits were delivered by the Department of Forests and Environment, Government of Meghalaya (No: FWC/G/173/Pt-II/295 dated May 8, 2014), Department of Environment and Forest of Arunachal Pradesh, Government of Arunachal Pradesh (No: CWL/G/13(95)/2011-12/Pt./2156-57 dated January 21, 2015), Department of Environment, Forest and Climate Change, Government of Nagaland (No: CWL/Gen/97/102-105 dated May 02, 2013 and No: CWL/Gen/97/659-661 dated February 04, 2014) to RGK. CD was supported by the Research Fund for International Scientists (RFIS) of the National Natural Science Foundation of China (NSFC) (N°3211101356). SM was partially supported by an Irish Research Council-Marie Skłodowska-Curie CAROLINE Fellowship (CLNE/2017/482). VKP and RGK were supported by the Rufford Foundation Small Grant (N°35454-1 and N°15255-1, respectively). DJ was supported by the Slovak Research and Development Agency (contract N°APVV19-0076). LJB and DAM were supported by the Zoological Institute of Russian Academy of Sciences (N°122031100282-2). Field trips of LJB, DAM, DVS and SNL to the Western Himalaya in 2011, 2013, 2015, and 2017 were organized by the Center for Himalayan Research, St. Petersburg Association of Scientists and Scholars. The data associated with this paper are available in Supplemental material - Files S1–S2, and new sequences were deposited in GenBank.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental material

Supplemental material for this article can be accessed here: https://doi.org/10.1080/14772000.2022.2102686.

Associate Editor: Dr David Gower