Consequences of parallel miniaturisation in Microhylinae (Anura, Microhylidae), with the description of a new genus of diminutive South East Asian frogs

Abstract

The genus Microhyla Tschudi, 1838 includes 52 species and is one of the most diverse genera of the family Microhylidae, being the most species-rich taxon of the Asian subfamily Microhylinae. The recent, rapid description of numerous new species of Microhyla with complex phylogenetic relationships has made the taxonomy of the group especially challenging. Several recent phylogenetic studies suggested paraphyly of Microhyla with respect to Glyphoglossus Günther, 1869, and revealed three major phylogenetic lineages of mid-Eocene origin within this assemblage. However, comprehensive works assessing morphological variation among and within these lineages are absent. In the present study we investigate the generic taxonomy of Microhyla–Glyphoglossus assemblage based on a new phylogeny including 57 species, comparative morphological analysis of skeletons from cleared-and-stained specimens for 23 species, and detailed descriptions of generalized osteology based on volume-rendered micro-CT scans for five species–altogether representing all major lineages within the group. The results confirm three highly divergent and well-supported clades that correspond with external and osteological morphological characteristics, as well as respective geographic distribution. Accordingly, acknowledging ancient divergence between these lineages and their significant morphological differentiation, we propose to consider these three lineages as distinct genera: Microhylasensu stricto, Glyphoglossus, and a newly described genus, Nanohylagen. nov.

Two new cryptic species of Microhyla Tschudi, 1838 (Amphibia, Anura, Microhylidae) related to the M. heymonsi group from central Vietnam

“…Our matrilineal genealogy is consistent with those of Matsui et al (2011), Peloso et al (2016), Nguyen et al (2019), Garg et al (2019), and Gorin et al (2020Gorin et al ( , 2021. The BI and ML genealogy showed that the monophyly of Microhylinae was not supported and the relationships among microhylid subfamilies remained unresolved (Nguyen et al 2019) (Fig.…”

“…Our matrilineal genealogy was consistent with previous studies based on mt DNA (e.g., Matsui et al 2005Matsui et al , 2011Hasan et al 2012;Matsui et al 2013;Howlader et al 2015;Wijayathilaka et al 2016;Seshadri et al 2016;Yuan et al 2016;Khatiwada et al 2017;Nguyen et al 2019;Garg et al 2019;and Hoang et al 2020). As shown in previous molecular analyses (Matsui et al 2011;Peloso et al 2016), Asian Microhyla species were divided into two geographical subgroups: the Southeast Asian subgroup was recently named as Nanohyla by Gorin et al (2021), with eight known species: N. annamensis, N. annectens, N. hongiaoensis, N. marmorata, N. nanapollexa, N. perparva, N. petrigena, and N. pulchella; and Pan-Asian, including all other South, Southeast, and East Asian members (Fig.…”

“…The genus Microhyla Tschudi, 1838 currently contains 44 species, which are distributed from India and Sri Lanka eastwards to the Ryukyu Archipelago of Japan and southwards to Indonesia (Hoang et al 2020;Gorin et al 2021;Frost 2021). Recently, Gorin et al (2021) described a new genus Nanohyla from the Microhyla -Glyphoglossus assemblage (currently called the Microhyla -Nanohyla -Glyphoglossus assemblage).…”

“…The genus Microhyla Tschudi, 1838 currently contains 44 species, which are distributed from India and Sri Lanka eastwards to the Ryukyu Archipelago of Japan and southwards to Indonesia (Hoang et al 2020;Gorin et al 2021;Frost 2021). Recently, Gorin et al (2021) described a new genus Nanohyla from the Microhyla -Glyphoglossus assemblage (currently called the Microhyla -Nanohyla -Glyphoglossus assemblage). Recent studies have discovered highly divergent mitochondrial DNA lineages indicating a high degree of undiagnosed diversity in the genus (Hasan et al 2012(Hasan et al , 2014(Hasan et al , 2015Howlader et al 2015;Matsui et al 2005Matsui et al , 2011Matsui et al , 2013Seshadri et al 2016;Wijayathilaka et al 2016;Yuan et al 2016;Zhang et al 2018;Nguyen et al 2019;Li et al 2019;Poyarkov et al 2019;Hoang et al 2020).…”

A new species of the genusMicrohylaTschudi, 1838 (Amphibia: Anura: Microhylidae) from eastern India with notes on Indian species

“…The genus Microhyla Tschudi, 1838 is the most widely distributed group across Asia. Currently the genus is comprised of 52 recognised species (Li et al, 2019; Biju et al, 2019; Gorin et al,2021) of which 13 species are known to occur in India, only four from north east region, one from Andaman and others from Western Ghats and southern states of India. Occurrence of M. pulchra and M. butleri in India is doubtful (Garg et al, 2019).…”