Unearthing the Fossorial Tadpoles of the Indian Dancing Frog Family Micrixalidae

PLoS One. 2016 Mar 30;11(3):e0151781. doi: 10.1371/journal.pone.0151781. eCollection 2016.

Abstract

Tadpoles of the monotypic Indian dancing frog family Micrixalidae have remained obscure for over 125 years. Here we report the discovery of the elusive tadpoles of Micrixalus herrei from the sand beds of a forested stream in southern Western Ghats, and confirm their identity through DNA barcoding. These actively burrowing tadpoles lead an entirely fossorial life from eggs to late metamorphic stages. We describe their internal and external morphological characters while highlighting the following features: eel-like appearance, extensively muscularized body and tail, reduced tail fins, skin-covered eyes, delayed development of eye pigmentation in early pre-metamorphic stages (Gosner stages 25-29), prominent tubular sinistral spiracle, large transverse processes on vertebrae II and III, ankylosed ribs on transverse processes of vertebra II, notochord terminating before the atlantal cotyle-occipital condyle junction, absence of keratodonts, serrated well-formed jaw sheaths, and extensive calcified endolymphatic sacs reaching sacrum posteriorly. The tadpole gut contains mostly fine sediments and sand. We discuss the eel-like morphology and feeding habits of M. herrei in the context of convergence with other well-known fossorial tadpoles. This discovery builds the knowledge base for further comparative analyses and conservation of Micrixalus, an ancient and endemic lineage of Indian frogs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anura / anatomy & histology
  • Anura / physiology*
  • DNA Barcoding, Taxonomic
  • Feeding Behavior / psychology*
  • Larva / anatomy & histology
  • Larva / physiology
  • Metamorphosis, Biological / physiology*
  • Ribs / anatomy & histology
  • Ribs / physiology*
  • Spine / anatomy & histology
  • Spine / physiology*

Grants and funding

This research was funded by DU/DST ‘2009/868’ (Government of India); MoEF ‘23/3/2007-RE’ (Government of India); CEPF ‘Project 55918/2009’ (USA); and University of Delhi ‘R&D 2012/917’ grants to SDB. MM is supported by the National Research Council (NRC-11-124). SG is supported by a research fellowship from the Council for Scientific and Industrial Research, India (CSIR No. 9/45(1381)/2015-EMR-I).