This extremely diverse family of frogs contains more than 800 species in approximately 50 genera. Leptodactylids occur primarily in the neotropics (tropical America and West Indies), with a few representatives in both northern and southern temperate America.
Leptodactylids are a wildly heterogeneous group of frogs for which not a single synapomorphy has been proposed. In all likelihood, Leptodactylidae includes multiple evolutionary lineages (see paragraph below on phylogeny). Most leptodactylids lack ribs, have teeth on their upper jaw, eight holochordal-procoelous presacral vertebrae, and an astragalus and calcaneum that are fused only at their ends. Amplexus may be axillary or inguinal. Adult size ranges from 10 to 250 mm snout-vent length. Leptodactylids are found from sea level to above tree line, with representative habits including fossorial, terrestrial, arboreal and aquatic. Diploid number ranges from 18 to 36, and some species are polyploid.
Leptodactylids are split into four subfamilies. Ceratophryinae (the "wide-mouthed toads") is a small group of large-headed, aggressive, carnivorous frogs. The horned frog, Ceratophrys calcarata, has been observed undulating its toes behind its head to lure prey to its mouth. Hylodinae is also a restricted group, its main claim to fame being that it has been hypothesized as a dendrobatid ancestor on the basis of similar cranial morphology and shared t-shaped terminal phalanges. If this hypothesis were true, Leptodactylidae would certainly not be monophyletic. Members of the subfamily Leptodactylinae are primarily terrestrial, foam-nest building frogs. By secreting mucus from their skin and reproductive tracts, which they then beat into a foam with their legs, reproductively mature individuals produce nests that protect the young from desiccation and other physical risks. In several species, a parent remains with the non-feeding tadpoles at the nest. Frogs of the genus Physalaemus have undergone extensive study for several decades now, work which has produced new advances in sexual selection and ecological theory.
The fourth subfamily, Telmatobiinae, is by far the largest and most diverse, and is probably not monophyletic. The genus Telmatobius is confined to the Andean highlands, and some of the 30 species live exclusively in alpine lakes at 4000 m altitude. The genus Eleutherodactylus, with more than 500 species, is itself perhaps not monophyletic. These frogs range from 12 to 80 mm snout-vent length, and may be semi-aquatic, terrestrial, or arboreal. Direct development of terrestrial eggs is the rule in Eleutherodactylus, the rare exceptions being viviparous and internally fertilized, an extremely rare character in frogs. Egg attendance by a parent is probably common.
Leptodactylids are unambiguously placed in the Neobatrachia, but relationships among the families of these "advanced" frogs is controversial at best. Most authors identify a superfamily, alternately called Bufonoidea or Hyloidea, which includes all the neobatrachians that are not Ranoids or Microhyloids. Leptodactylids are clearly part of Bufonoidea, but the monophyly of Leptodactylidae is in much doubt. Leptodactylids have been considered by some authors to be those non-myobatrachid bufonoids that lack synapomorphies that characterize other families, such as intercalary cartilages (Hylidae, Pseudidae, Centrolenidae), or a Bidder's organ (Bufonidae). The remaining small families in Bufonoidea (Rhinodermatidae, Brachycephalidae, Sooglossidae, Heleophrynidae) have derived features that distinguish them from the leptodactylids. Within Leptodactylidae, three of the four subfamilies appear to be monophyletic, but Telmatobiinae almost certainly is not. Within the Bufonoidea, Leptodactylidae is analagous to the Ranidae within the Ranoidea: both families represent a diverse, paraphyletic group of non-treefrogs. The leptodactylids are the new world counterparts to the primarily old world ranids.
Fossil leptodactylids are widespread in Cenozoic deposits throughout South America. Additionally, Pleistocene fossils have been recovered in North America and the West Indies.
Adler, K., and T. R. Halliday, editors. 1986. Reptiles and Amphibians. Torstar Books Inc., New York.
Cannatella, D. 1996. Leptodactylidae: Tree of Life. (Website.) http://tolweb.org/tree?group=Leptodactylidae&contgroup=Neobatrachia
Cogger, H. G., and R. G. Zweifel, editors. 1998. Encyclopedia of Reptiles and Amphibians, 2nd edition. Academic Press, San Diego.
Duellman, W. E., and L. Trueb. 1986. Biology of Amphibians. Johns Hopkins University Press, Baltimore, MD.
Lynch, J. D. 1971. Evolutionary relationships, osteology, and zoogeography of leptodactyloid frogs. Misc. Publ. Mus. Nat. Hist. Univ. Kansas (53):531-238.
Pough, F. H., R. M. Andrews, J. E. Cadle, M. L. Crump, A. H. Savitzky, and K. D. Wells. 1998. Herpetology. Prentice-Hall, Inc., Upper Saddle River, NJ.
Stebbins, R. C., and N. W. Cohen. 1995. A natural history of amphibians. Princeton University Press, Princeton.
Zug, G. R. 1993. Herpetology: an introductory biology of amphibians and reptiles. Academic Press, San Diego.
Heather Heying (author).
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
having the capacity to move from one place to another.