Phylogeny, Diversity, and Distribution of Micryletta (Anura: Microhylidae) in Myanmar

Aryeh H Miller,George R Zug,Justin L Lee,Guinevere O U Wogan,Daniel G Mulcahy

doi:10.1643/h2020100

Abstract

The microhylid genus Micryletta, often called Paddy Frogs, is a taxonomically modest group of frogs currently comprised of eight species distributed across India, China, and Southeast Asia. None of the recent investigations into this group have explicitly focused on the diversity of these frogs in Myanmar, a critically undersampled region previously thought to contain only one species of Micryletta, M. inornata. Recent field expeditions to Myanmar conducted by the authors have resulted in the discovery of numerous populations of Micryletta in the northern and southern portions of the country in Kachin State and Tanintharyi Region, respectively. In this study, we investigate the status of these populations, their taxonomic identities, and broadly assess the diversity of this enigmatic group of frogs in Myanmar. Using comparative morphological and molecular data, we find the diversity of Micryletta in Myanmar has been poorly appreciated, which we demonstrate with the discovery of M. aishani, a species previously only known from neighboring India, and M. lineata, a species originally described from Peninsular Thailand. Our investigation into the taxonomic status of M. lineata demonstrates the validity in the recognition of this species, which is supported with evidence derived from morphology, geography, and molecular data. We additionally provide a detailed re-description of this species based on novel specimens from southern Myanmar. We also document M. inornata sensu stricto in Myanmar, sympatric with M. lineata, bringing the total to three species of Micryletta occurring in Myanmar.

Highlights

The microhylid genus Micryletta, often called Paddy Frogs, is a taxonomically modest group of frogs currently comprised of eight species distributed across India, China, and Southeast Asia
In both the 16S and cytochrome-oxidase I (COI) phylogenies, sympatric Tanintharyi populations of M. inornata and M. lineata were placed into two, distantly related clades: 1) two specimens (USNM 587625, 587901) were placed in a clade with topotypic M. inornata sensu stricto, in the COI reconstruction sister to all other Paddy Frogs (UFBoot 1⁄4 91), and in the 16S reconstruction sister to M. aishani, M. cf. inornata, M. erythropoda, and M. lineata (UFBoot 1⁄4 72); and 2) all remaining Tanintharyi specimens were placed in a separate clade nested deeper in the tree sister to M. erythropoda with moderate to high support (UFBoot 1⁄4 80; UFBoot 1⁄4 98)
The discovery of M. inornata sensu stricto in southern Myanmar is perhaps more surprising given that it is otherwise known from approximately 700 km south in Sumatra

Summary

Introduction

The microhylid genus Micryletta, often called Paddy Frogs, is a taxonomically modest group of frogs currently comprised of eight species distributed across India, China, and Southeast Asia. Alhadi et al (2019) used mitochondrial sequence data (16S rRNA) to determine the phylogenetic position of topotypic Sumatran populations of M. inornata relative to other Asian Micryletta, which were recovered as sister to a larger clade composed of M. erythropoda, M. steinegeri, and multiple other clades containing candidate species previously considered to belong to M. inornata. During recent surveys conducted by us in the northern province of Kachin State (GOUW) and the southern province of Tanintharyi Region (DGM), we discovered novel populations of microhylid frogs matching the diagnosis of Micryletta (Dubois, 1987) We leverage these specimens to investigate diversity of this genus in Myanmar, which we supplement with additional natural history museum specimens and previously published sequence data from populations across mainland Southeast Asia and Sundaland. Using morphological and molecular data, we examine the status of M. inornata in Myanmar, and investigate intra- and interspecific variation within this group throughout Southeast Asia

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Results

Conclusion