True frog


The true frogs, family Ranidae, 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, and Asia. The Asian range extends across the East Indies to New Guinea and a single species 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 —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 with 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.

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. 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.
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:
A number of taxa are placed in Ranidae incertae sedis, that is, their taxonomic status is too uncertain to allow more specific placement.