[Herpetology • 2017] Evolutionary History of the Asian Horned Frogs (Megophryinae): Integrative Approaches to Timetree Dating in the Absence of a Fossil Record

DOI: 10.1093/molbev/msw267  

Molecular dating studies typically need fossils to calibrate the analyses. Unfortunately, the fossil record is extremely poor or presently non-existent for many species groups, rendering such dating analysis difficult. One such group is the Asian horned frogs (Megophryinae). Sampling all generic nomina, we combined a novel ∼5kb dataset composed of four nuclear and three mitochondrial gene fragments to produce a robust phylogeny, with an extensive external morphological study to produce a working taxonomy for the group. Expanding the molecular dataset to include out-groups of fossil represented ancestral anuran families, we compared the priorless RelTime dating method with the widely used prior based Bayesian timetree method, MCMCtree, utilising a novel combination of fossil priors for anuran phylogenetic dating. The phylogeny was then subjected to ancestral phylogeographic analyses, and dating estimates were compared with likely biogeographic vicariant events. Phylogenetic analyses demonstrated that previously proposed systematic hypotheses were incorrect due to paraphyly of genera. Molecular phylogenetic, morphological and timetree results support the recognition of Megophryinae as a single genus, Megophrys, with a subgenus level classification. Timetree results using RelTime better corresponded with the known fossil record for the outgroup anuran tree. For the priorless in-group, it also outperformed MCMCtree when node date estimates were compared with likely influential historical biogeographic events, providing novel insights into the evolutionary history of this pan-Asian anuran group. Given a relatively small molecular dataset, and limited prior knowledge, this study demonstrates that the computationally rapid RelTime dating tool may outperform more popular and complex prior reliant timetree methodologies.

Keywords: amphibian, phylogenetics, taxonomy, biogeography, timetree, Megophryidae, India, Asia.

Stephen Mahony, Nicole M. Foley, S.D.Biju and Emma C. Teeling. 2017. Evolutionary History of the Asian Horned Frogs (Megophryinae): Integrative Approaches to Timetree Dating in the Absence of a Fossil Record.  Molecular Phylogenetics and Evolution.  DOI: 10.1093/molbev/msw267 

[Herpetology • 2013] Three New Species of Horned Frogs, Megophrys (Amphibia: Megophryidae); Megophrys ancrae, M. vegrandis & M. oropedion, from Northeast India, with a resolution to the identity of Megophrys boettgeri populations reported from the region

Megophrys ancrae sp. nov. and Megophrys vegrandis sp. nov. from Arunachal Pradesh;  Megophrys oropedion sp. nov. from the Shillong Plateau, eastern Meghalaya, northeastern India

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Abstract

Northeast India is a well-established region of biological importance but remains poorly understood with regards to the species level identifications of many of its extant amphibians. In this study we examined small sized frogs from the genus Megophrys recently collected from remote and suburban forests in the northeast Indian states of Meghalaya and Arunachal Pradesh, from which we have identified three new species. Megophrys vegrandis sp. nov., Megophrys ancrae sp. nov. and Megophrys oropedion sp. nov. are compared with all known congeners from India and surrounding regions from which they differ based primarily on a combination of morphological characters. Megophrys boettgeri is removed, and Megophrys minor added to the Indian amphibian checklist, through critical review of all literature pertaining to the former species, and the discovery of an overlooked historical report of the latter species.

Two of the new species, Megophrys ancrae sp. nov. and Megophrys vegrandis sp. nov. are known from low and mid elevations within two large protected forests in Arunachal Pradesh, both with poorly studied amphibian fauna. Contrastingly, Megophrys oropedion sp. nov. is currently known only from small forested areas on the upper reaches of the Shillong Plateau. The importance of the Shillong Plateau as an area of known high amphibian endemicity is highlighted in the light of the miniscule proportion of its land area afforded government protection, raising concerns about the future conservation of its still poorly known species.

Key words: Amphibian; taxonomy; morphology; chresonymy; Megophryinae; Megophrys parva; baluensis; montana; Philautus kempii

Mahony, Stephen, Emma C. Teeling & S. D. Biju. 2013. Three New Species of Horned Frogs, Megophrys (Amphibia: Megophryidae), from Northeast India, with a resolution to the identity of Megophrys boettgeri populations reported from the region. Zootaxa. 3722(2): 143-169.

http://mapress.com/zootaxa/2013/f/z03722p169f.pdf

[Herpetology • 2011] Xenophrys (Megophrys) takensis • western Thailand | X. (M.) damrei • south Cambodia

Xenophrys (Megophrys) takensis

Abstract

Two new species of the genus Megophrys are described from historical collections presented by Malcolm A. Smith to The Natural History Museum, London, in the early twentieth century. These specimens were previously misidentified as Megophrys parva, a widespread Asian species apparently comprised of a species complex. Megophrys damrei sp. nov., from the Bokor Plateau in the Cardamom Mountains of southern Cambodia and Megophrys takensis sp. nov., from Ban Pa Che, Tak Province, in western Thailand, are herein distinguished morphologically from all congeners from their respective and neighbouring countries. These, or further specimens representing either species, do not appear to have been reported on by other authors in the past and the conservation status of the two new species remains to be assessed. An attempt to locate both species at and near their respective type localities was successful for Megophrys takensis sp. nov., allowing the documentation of observations in the wild and live colouration. This study highlights the importance of examining historical museum collections often overlooked in recent decades by modern taxonomists.

Key words: Xenophrys, taxonomy, new species, Thailand, Cambodia, amphibian

Megophrys takensis sp. nov.

2 new: Xenophrys (Megophrys) takensis • western Thailand

Xenophrys (Megophrys) damrei • southern Cambodia

Megophrys damrei sp. nov.

FIGURE 5. Megophrys takensis sp. nov. adult male in life, not collected, from Taksin Maharat National Park; A. lateral view, B. dorsolateral view, C. stream habitat at observation site, D. view of forest from above the canopy.

Mahony, S. 2011. Two new species of Megophrys Kuhl & van Hasselt (Amphibia: Megophryidae), from western Thailand and southern Cambodia. Zootaxa 2734: 23–39