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| Leptobrachium mechuka Leptobrachium somani Sarmah, Garg, Tajo, Upadhyaya, Hanken & Biju, 2026 |
Abstract
Of the 39 currently recognized species in the Slender Armed Frog genus Leptobrachium, four are reported from India, Leptobrachium aryatium, L. bompu, L. smithi, and L. sylheticum. Based on new collections, we review these reported species by integrating molecular, morphological, and behavioral data. Our comparative analyses of external and internal morphology as well as molecular data and acoustic properties reveal two new species-level lineages from the Lower Dibang Valley and Shi Yomi districts of Arunachal Pradesh, India, which we describe here as new species. Phylogenetically, Leptobrachium mechuka sp. nov. and Leptobrachium somani sp. nov. are members of the L. bompu species group, but they are distinct from L. bompu sensu stricto by DNA sequence divergence in the 16S mitochondrial rRNA gene of 3.6–4.2% and 4.5–4.7%, respectively. A population previously identified as L. cf. bompu from Medog County, China, is also assignable to Leptobrachium mechuka sp. nov. Each new species is distinguished from congeners by a combination of diagnostic morphological characters, including in the case of Leptobrachium somani sp. nov., a unique advertisement call comprising two distinct call types; unicolored silvery white iris; moderately large webbing between toes; and ventral coloration. Leptobrachium mechuka sp. nov. on the other hand, is distinguishable by its head length equal to width; nostril equidistant from the snout tip and the eye; internarial distance equal to the distances from nostril to eye and from nostril to snout tip; distance from the tip of inner metatarsal tubercle to the tip of first toe shorter than the length of inner metatarsal tubercle itself; and frontoparietals separated at the midline by a moderate fontanelle. Analyses of multiple new populations representing members of the L. smithi group reveal that L. smithi is absent from the Indian fauna; all previous records attributed to this species from India instead represent L. aryatium or L. sylheticum. These discoveries highlight the prevalence of taxonomic misidentifications in the absence of detailed systematic studies as well as the underestimation of diversity in the genus Leptobrachium, not only from India but across its known range. Our results underscore the need for dedicated surveys that document amphibian diversity in underexplored regions of Northeast India.
Keywords: Amphibia, Arunachal Pradesh, Bioacoustics, Cranial osteology, Integrative taxonomy, Leptobrachium bompu group, Leptobrachium smithi group, Mitochondrial phylogeny, Northeast India, Tadpoles
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| Phylogenetic relationships of the genus Leptobrachium and geographical distribution of species in India. |
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| Geographical distributions of five Leptobrachium species herein recognized to occur in India. |
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| Distribution of Leptobrachium bompu and L. smithi species groups in South and Southeast Asia. |
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| Holotype and paratype of Leptobrachium mechuka sp. nov. in life. (A–J) Holotype ZSI A16315: (A) Dorsolateral view. (B) Dorsal view. (C) Ventral view. (D) Lateral view. (E) Posterior view of thighs. (F) Dorsal view of thighs. (G) Ventral view of hand. (H) Enlarged view of palmar tubercles on hand. (I) Ventral view of foot. (J) Dorsal view of foot. (K) Referred specimen (SDBDU 2025.6768) Dorsolateral view. (L, M) Paratype (ZSI A16316). (L) Dorsolateral view. (M) Enlarged view of eye. Photographs: T. Tajo. |
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| Holotype and paratypes of Leptobrachium somani sp. nov. in life. (A–D) Dorsolateral view: (A) Paratype (ZSI A16335). (B) Paratype (ZSI A16336). (C) Referred specimen (SDBDU 2025.6773). (D) Holotype (ZSI A16333). (E–G) Paratype (ZSI A16336): (E) Frontal view. (F) Lateral view of head. (G) Enlarged view of eye. Photographs: S.D. Biju. |
Leptobrachium mechuka sp. nov.
Leptobrachium somani sp. nov.,
A.N. Dikshit Akalabya Sarmah, Sonali Garg, Tage Tajo, Radhakrishna Upadhyaya K., James Hanken and S.D. Biju. 2026. Abundance in Secret: A Review of the Genus Leptobrachium (Anura, Megophryidae) in India, with Descriptions of Two New Species. PeerJ. 14:e20397. DOI: doi.org/10.7717/peerj.20397 [January 9, 2026]