Molecular Identification and Description of the Tadpole of Leptobrachella melanoleuca (Matsui, 2006) (Amphibia: Anura: Megophryidae)

Abstract

Identifying tadpoles will significantly enhance future studies on life histories, behavior, ecology, and distribution of amphibian species. This study provides a detailed morphological and buccopharyngeal description of Leptobrachella melanoleuca tadpoles, utilizing DNA barcoding for accurate identification. Ten tadpoles, measuring 15.0±1.22 mm (range: 12.0–16.6 mm) in body length, were collected from Khlong Saeng Wildlife Sanctuary, Surat Thani Province, southern Thailand. Mitochondrial gene sequences, including 12S rRNA, tRNA-Val, and 16S rRNA, showed less than 0.1% divergence from adult L. melanoleuca in GenBank and our adult specimens, confirming the identification. Both tadpoles and adults were found in a small rocky stream. The tadpoles exhibit dark brown coloration with brown blotches in life, while preserved specimens show significant fading. The tadpoles’ external morphology includes a translucent abdomen, darkened throat, and dark gray chest. The tail musculature is gray with light brown spots, and the fins are slightly transparent. Buccopharyngeal anatomy revealed a semicircular prenarial arena with knobby projections, narrow choanae, and a densely pustular buccal roof arena. The buccal floor features triangular tongue anlage, trapezoidal prelingual arena, and large buccal floor arena papillae. The Keratodont Row Formula (KRF) is recorded as 1:2–2/0 or 2+2/0, with black jaw sheaths. These findings contribute significantly to our understanding of tadpole morphology in the genus Leptobrachella, providing a crucial reference for future taxonomic and ecological studies of this and related species.