A new species of the horned toad Megophrys Kuhl &amp; Van Hasselt, 1822 (Anura, Megophryidae) from southwest China

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Abstract

A new species of the genus Megophrys is described from Guizhou Province, China. Molecular phylogenetic analyses based on mitochondrial DNA and nuclear DNA sequences all strongly supported the new species as an independent clade sister to M. minor and M. jiangi. The new species could be distinguished from its congeners by a combination of the following characters: body size moderate (SVL 43.4–44.1 mm in males, and 44.8–49.8 mm in females; vomerine teeth absent; tongue not notched behind; a small horn-like tubercle at the edge of each upper eyelid; tympanum distinctly visible, rounded; two metacarpal tubercles on palm; relative finger lengths II < I < V < III; toes without webbing; heels overlapping when thighs are positioned at right angles to the body; tibiotarsal articulation reaching the level between tympanum and eye when leg stretched forward; in breeding males, an internal single subgular vocal sac in male, and the nuptial pads with black spines on dorsal surface of bases of the first two fingers.

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We studied the importance of proper model assumption in the context of Bayesian phylogenetics by examining >5,000 Bayesian analyses and six nested models of nucleotide substitution. Model misspecification can strongly bias bipartition posterior probability estimates. These biases were most pronounced when rate heterogeneity was ignored. The type of bias seen at a particular bipartition appeared to be strongly influenced by the lengths of the branches surrounding that bipartition. In the Felsenstein zone, posterior probability estimates of bipartitions were biased when the assumed model was underparameterized but were unbiased when the assumed model was overparameterized. For the inverse Felsenstein zone, however, both underparameterization and overparameterization led to biased bipartition posterior probabilities, although the bias caused by overparameterization was less pronounced and disappeared with increased sequence length. Model parameter estimates were also affected by model misspecification. Underparameterization caused a bias in some parameter estimates, such as branch lengths and the gamma shape parameter, whereas overparameterization caused a decrease in the precision of some parameter estimates. We caution researchers to assure that the most appropriate model is assumed by employing both a priori model choice methods and a posteriori model adequacy tests.

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Phylogenetic systematics and biogeography of hummingbirds: Bayesian and maximum likelihood analyses of partitioned data and selection of an appropriate partitioning strategy.

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Rapid diversification and dispersal during periods of global warming by plethodontid salamanders.

David Wake, D R Vieites, Mi-Sook Min (2007)

A phylogeny and timescale derived from analyses of multilocus nuclear DNA sequences for Holarctic genera of plethodontid salamanders reveal them to be an old radiation whose common ancestor diverged from sister taxa in the late Jurassic and underwent rapid diversification during the late Cretaceous. A North American origin of plethodontids was followed by a continental-wide diversification, not necessarily centered only in the Appalachian region. The colonization of Eurasia by plethodontids most likely occurred once, by dispersal during the late Cretaceous. Subsequent diversification in Asia led to the origin of Hydromantes and Karsenia, with the former then dispersing both to Europe and back to North America. Salamanders underwent rapid episodes of diversification and dispersal that coincided with major global warming events during the late Cretaceous and again during the Paleocene-Eocene thermal optimum. The major clades of plethodontids were established during these episodes, contemporaneously with similar phenomena in angiosperms, arthropods, birds, and mammals. Periods of global warming may have promoted diversification and both inter- and transcontinental dispersal in northern hemisphere salamanders by making available terrain that shortened dispersal routes and offered new opportunities for adaptive and vicariant evolution.

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Author and article information

Journal

Title: ZooKeys

Abbreviated Title: ZK

Publisher: Pensoft Publishers

ISSN (Electronic): 1313-2970

ISSN (Print): 1313-2989

Publication date Created: June 22 2020

Publication date (Electronic): June 22 2020

Volume: 943

Pages: 119-144

Article

DOI: 10.3897/zookeys.943.50343

SO-VID: 050c4025-4c8d-4e6b-9933-fa21e506f4d6

License:

http://creativecommons.org/licenses/by/4.0/

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