True Frog

True frogs is the common name for the frog family Ranidae. They have the widest distribution of any frog family. They are abundant throughout most of the world, occurring on all continents except Antarctica. The true frogs are present in North America, northern South America, Europe, Africa (including Madagascar), and Asia. The Asian range extends across the East Indies to New Guinea and a single species (the Australian wood frog (''Hylarana daemelii'')) has spread into the far north of Australia.

Typically, true frogs are smooth and moist-skinned, with large, powerful legs and extensively webbed feet. The true frogs vary greatly in size, ranging from small—such as the wood frog (''Lithobates sylvatica'')—to large.

Many of the true frogs are aquatic or live close to water. Most species lay their eggs in the water and go through a tadpole stage. However, as in most families of frogs, there is large variation of habitat within the family. There are also arboreal species of true frogs, and the family includes some of the very few amphibians that can live in brackish water.

Evolution

The Ranidae are related to several other frog families that have Eurasian and Indian origins, including Rhacophoridae, Dicroglossidae, Nyctibatrachidae, Micrixalidae, and Ranixalidae. They are thought to be most closely related to the Indian-endemic Nyctibatrachidae, from which they diverged in the early Eocene. However, other studies recover a closer relationship with the Dicroglossidae.

It was previously thought that the Ranidae and their closest relatives were of Gondwanan origins, having evolved on Insular India during the Cretaceous. They were then entirely restricted to the Indian subcontinent until the late Eocene, when India collided with Asia, allowing the Ranidae to colonize Eurasia and eventually the rest of the world. However, more recent studies instead propose that the Ranidae originated in Eurasia, and their close relationship with India-endemic frog lineages is due to those lineages colonizing India from Eurasia during the Paleogene.

Systematics

The subdivisions of the Ranidae are still a matter of dispute, although most are coming to an agreement. Several former subfamilies are now recognised as separate families ( Petropedetidae, Cacosterninae, Mantellidae, and Dicroglossidae). The genus ''Rana'' has now been split up and is much reduced in size.

While too little of the vast diversity of true frogs has been subject to recent studies to say something definite, as of mid-2008, studies are going on, and several lineages are recognizable.
* The genus '' Staurois'' is probably a very ancient offshoot of the main Raninae lineage.
* ''Amolops'' has been generally delimited as a monophyletic group.
* '' Odorrana'' and ''Rana'' plus some proposed minor genera (which probably ought to be included in the latter) form another group.
* A group including ''Clinotarsus'', '' Huia'' in the strict sense and '' Meristogenys''
* An ill-defined assemblage of '' Babina'', ''Glandirana'', '' Hylarana'', ''Pulchrana'', ''Sanguirana'', and ''Sylvirana'', as well as ''Hydrophylax'' and ''Pelophylax'', which are probably not monophyletic. Some authorities have treated them as junior synonyms of the genus '' Hylarana''.
The following phylogeny of some genera was recovered by Che ''et al''., 2007 using mitochondrial genes.

Genera

Most of the subfamilies formerly included under Ranidae are now treated as separate families, leaving only Raninae remaining. The following genera are recognised in the family Ranidae:

* ''Abavorana'' Oliver, Prendini, Kraus, and Raxworthy, 2015
* '' Amnirana'' Dubois, 1992
* ''Amolops'' Cope, 1865
* '' Babina'' Thompson, 1912
* ''Chalcorana'' Dubois, 1992
* ''Clinotarsus'' Mivart 1869
* ''Glandirana'' Fei, Ye, and Huang, 1990
* '' Huia'' Yang, 1991
* ''Humerana'' Dubois, 1992
* ''Hydrophylax'' Fitzinger, 1843
* '' Hylarana'' Tschudi 1838
* ''Indosylvirana'' Oliver, Prendini, Kraus, and Raxworthy, 2015
* '' Lithobates'' Fitzinger, 1843
* '' Meristogenys'' Yang, 1991
* '' Nidirana'' Dubois, 1992
* '' Odorrana'' Fei, Ye, and Huang, 1990
* '' Papurana'' Dubois, 1992
* ''Pelophylax'' Fitzinger 1843
* '' Pseudorana'' Fei, Ye, and Huang, 1990
* '' Pterorana'' Kiyasetuo and Khare, 1986
* ''Pulchrana'' Dubois, 1992
* ''Rana'' Linnaeus, 1758
* ''Sanguirana'' Dubois, 1992
* '' Staurois'' Cope, 1865
* '' Sumaterana'' Arifin, Smart, Hertwig, Smith, Iskandar, and Haas, 2018
* ''Sylvirana'' Dubois, 1992
* '' Wijayarana'' Arifin, Chan, Smart, Hertwig, Smith, Iskandar, and Haas, 2021

''Incertae sedis''

A number of taxa are placed in Ranidae ''incertae sedis'', that is, their taxonomic status is too uncertain to allow more specific placement.
* "''Hylarana''" ''chitwanensis'' (Das, 1998)
* "''Hylarana''" ''garoensis'' (Boulenger, 1920)
* "''Hylarana''" ''latouchii'' (Boulenger, 1899)
* "''Hylarana''" ''margariana'' Anderson, 1879
* "''Hylarana''" ''montivaga'' (Smith, 1921)
* "''Hylarana''" ''persimilis'' (Van Kampen, 1923)

See also

*Halipegus eccentricus, a monoecious, digenea parasitic trematode commonly found in true frogs in North America

References

* (2004): ''Encyclopedia of Reptiles & Amphibians'' (2nd ed.). Fog City Press.
* (2006): Amphibian Species of the World Version 3
Petropedetidae Noble, 1931
American Museum of Natural History, New York, USA. Retrieved 2006-AUG-05.
* (2006): The amphibian tree of life. Bulletin of the American Museum of Natural History. Number 297. New York.
* (2007) Constraints in naming parts of the Tree of Life. '' Mol. Phylogenet. Evol.'' 42 (2): 331–338. PDF fulltext

* (2005): Phylogeny of the New World true frogs (''Rana''). '' Mol. Phylogenet. Evol.'' 34 (2): 299–314. PDF fulltext

* (2009): Taxonomic freedom and the role of official lists of species names. ''Herpetologica'' 65: 115-128.
* (2007): "''Fine del prodromo d'erpetologia siciliana'' ". ''Specchio delle Scienze, o, Giornale Enciclopedico di Sicilia'' 2: 102-104. (Ranidae, new family). (in Italian).

{{Authority control

*
Taxa named by Constantine Samuel Rafinesque