Cryptic diversity within the Megophrys major species group (Amphibia: Megophryidae) of the Asian Horned Frogs: Phylogenetic perspectives and a taxonomic revision of South Asian taxa, with descriptions of four new species

Abstract

The Megophrys major species group (MMSG) is composed of typically medium to large sized frogs. Within the genus, it is the most geographically widespread clade ranging from the western Himalayas to southern Indochina. In this study, we examined in detail the extent of cryptic diversity within the MMSG-Indian populations based on molecular data (up to ten genes) using multigene concatenation and coalescent-based phylogenetic techniques, species delimitation analyses and extensive morphological data.Molecular evidence suggests a high level of hidden cryptic diversity within the MMSG, particularly within the M. major species complex (MMC), highlighting overlapping distributions, a case of potential mitochondrial transfer between two species, and tree topology discordance between phylogenetic methods and mitochondrial and nuclear data sets. Most analyses indicated distinct eastern and western clades in the MMC, and that the western clade may further divide into a northern and a southern subclade.A detailed taxonomic review of Indian members of the Megophrys major species group is provided. Previously undocumented complex nomenclatural issues involving known species are highlighted and resolved. Megophrys monticola is taxonomically redefined for the first time as a valid species since its synonymy with M. parva in 1893. The taxonomic status of two recently described species, Xenophrys katabhako and X. sanu are discussed in light of increased molecular and morphological sampling, and are synonymised with M. monticola. Megophrys monticola and M. robusta are redescribed based on their original type specimens and recently collected material. Megophrys major is neotypified and M. robusta lectotypified to remove prevailing nomenclatural instability. Four new large sized Indian MMC species are formally described from the Northeast Indian states of Arunachal Pradesh, Meghalaya and Nagaland, and Myanmar. All South Asian MMSG species are morphologically diagnosed from known congeners in the group. The geographic distributions of all taxa discussed are significantly redefined based on the revised taxonomy and extensive literature review. Morphological and molecular evidence suggests that Megophrys major sensu stricto might be endemic to Northeast India; M. glandulosa is formally removed from the Indian and Bhutan species checklists. Numerous misidentifications in literature are highlighted and corrected. In order to reduce future misidentifications of species reported from surrounding regions, high definition images of the holotypes of three Chinese species, M. glandulosa, M. medogensis and M. zhangi are provided for the first time, and a detailed description of Myanmar specimens of M. glandulosa is also given. This study provides the principle foundation for further research into the taxonomic status of the remaining, currently undescribed MMC taxa from Southeast Asia.

On the systematic status of the genus Oriocalotes Günther, 1864 (Squamata: Agamidae: Draconinae) with the description of a new species from Mizoram state, Northeast India

“…Jerdon (1870) notes that he was aware that several of the localities given by the brothers Schlagintweit were erroneous "probably from the displacement of labels". Furthermore, collection localities associated with some of Jerdon's specimens from "Sikkim" have also been demonstrated to have been mislabeled for species otherwise found only in the Khasi Hills (Biju et al 2016;Mahony et al 2018). Jerdon (1870) also admits to not having seen this species, despite presenting specimens to the BMNH (NHMUK) soon after.…”

Multiple data revealed two new species of the Asian horned toad Megophrys Kuhl & Van Hasselt, 1822 (Anura, Megophryidae) from the eastern corner of the Himalayas

“…The morphological comparisons between adults of the two groups were not applicable in this work because no adults of the high-elevation groups were collected. The scenario of phylogenetical discordance between different gene datasets was also found in M. monticola (Mahony et al 2018). The mechanism of two discovered cases of introgression from southeastern Himalayan is fascinating for further study.…”

“…nov. in the same stream, indicating the "sympatric but phylogenetically distant" model. These biogeographical patterns have often been found in Megophrys (Mahony et al 2018;Liu et al 2018;Wang et al 2019), indicating a complicated picture of biogeographical history of this taxonomically diverse toad group.…”

“…What's more, molecular phylogenetic studies still put forward dozens of cryptic species in the group (Chen et al 2016;Liu et al 2018). Misleading taxonomic judgements without precise and adequate comparisons and insufficient field work often hinder the discovery of cryptic diversity in the group (Mahony et al 2018;Liu et al 2018). Hence, comprehensive examinations with multiple data (e.g., molecular phylogenetic, morphological, and bioacoustics data) are needed for describing new taxon and furtherly recognizing underestimated species diversity in this diverse group.…”

A new Megophrys Kuhl & Van Hasselt (Amphibia, Megophryidae) from southeastern China

“…It currently contains 92 recognised species (Frost 2019), and noticeably, 37 species were described in the last decade (See species list of Megophrys in Frost 2019). The genus is suggested to harbour both cryptic diversity and highly localised species diversification (Chen et al 2017;Mahony et al 2017Mahony et al , 2018Liu et al 2018). For example, in the genus, just in China, 41 cryptic species were suggested by molecular phylogenetic analyses in , and six of them were subsequently described (Li et al 2018;Wang et al 2019).…”