Morphology identification and DNA barcoding of frogs species in the Mekong delta

Abstract

This study was aimed to identify species names of some wild and cultured frogs in the Mekong Delta using morphological and DNA barcoding approaches. Cultured frogs were collected from An Giang (80) and Dong Thap (22), wild frog from Soc Trang (7) and Can Tho (2), and crab-eating frogs from Soc Trang (25). Frog samples were first identified by external morphological features and measured morphometric parameters. Then, 23 samples from four populations/species were sequenced their COI gene. Results of the external morphology show that body features and morphological indices of cultured frogs from An Giang and Dong Thap were totally similar, while they differed from wild frogs in only index (nostril to upper jaws). Crab-eating frogs were completely distinct, with 20/26 indices significantly different form the others. The alignment of COI sequences with GenBank and Bold systems databases showed that crab-eating frog samples were identified as Fejervarya cancrivora. The cultured and wild frogs both matched with Hoplobatrachus rugulosus, with discrepancies among published sequences; therefore, their species level could not be solved. However, K2P genetic distance between the cultured and wild frog was high (0.167 ± 0.018), indicating that they could be different species. Broader research coevering both Thailand and more part of Vietnam is needed to identify frog species.