Hyloids

Allophrynidae. Allophryne (one genus, one species) is an enigmatic treefrog of the Guianas in South America. It superficially resembles the hylids and centrolenids, but some authors have allied it with the bufonids. Its reproductive mode is unknown.

Brachycephalidae. The brachycephalids are a group of miniature frogs in coastal southeastern Brazil (two genera, five species) with reduced digits. They have direct development within terrestrial eggs, and one genus has a peculiar osseous shield on its back.

Bufonidae. The "true" toads (32 genera, 423 species) are variable, from delicate treefrog-like forms to giant toads about the size of a pie plate. Primitive bufonids lay individual eggs, but members of Bufo and its near allies (the large majority of the species in the family) generally lay strings of eggs. A number of taxa lack feeding tadpoles, some are direct developers, and some are ovoviviparous.

Heleophrynidae. The ghost frogs (one genus, five species) are frogs of moderate size that inhabit high gradient rocky streams. They would likely have been placed in the Lepto-dactylidae had they occurred in South America, or in the Myobatrachidae had they occurred in Australia. However, because they are South African endemics, most authors have treated them as a distinct family.

"Leptodactylidae." The "Leptodactylidae" are a collection of New World hyloid frogs (48 genera, 1,068 species), very likely paraphyletic with at least some of the other groups of hyloids, and characterized by lacking the derived characteristics of other groups. Lep-

todactylids are found from the southern United States and the Antilles to the southern tip of South America. The largest vertebrate genus, the rainfrogs of the genus Eleutherodactylus, are in this group (approximately 680 species), but the diversity in leptodactylids in terms of body plan and reproductive mode varies from the large-headed predatory Ceratophrys; to the obligately aquatic members of Telmatobius, which live their lives on the bottom of Andean lakes; to the rain frogs that live primarily in leaf litter in cloud forests. Primitively, the lepto-dactylids have aquatic eggs and larvae, but all members of the eleutherdactylines have direct development within terrestrial eggs; at least one member, Eleutherodactylus jasperi (likely now extinct), is viviparous.

"Myobatrachidae." The myobatrachid frogs (22 genera, 120 species) are an extremely variable collection of hyloid species found in Australia and New Guinea that lack any of the obvious derived features associated with other neobatrachian families. As such the Myoba-trachidae are likely artificial. Reproductive modes are similarly variable in the group. Rheobatrachus, the endangered gastric-brooding frogs, are members of this nominal group, and a few exhibit nonfeeding tadpoles in nests; others have direct development in terrestrially laid eggs, although most of the species have free-living tadpoles and are otherwise similar to the "Leptodactylidae."

Sooglossidae. The Sooglossidae (two genera, three species) are a taxon of hyloid frog restricted to the Seychelles Islands of the Indian Ocean, and clearly these represent ancient relicts of the breakup of Gondwana-land. The eggs are laid on the land, and there is either direct development (Sooglossus) or nonfeeding tadpoles that are carried on the back of the adult (Nesomantis).

Rhinodermatidae. The rhinodermatids (one genus, two species) are a peculiar group of hyloid frogs found in the temperate forests of southern Chile and Argentina. They exhibit a peculiar reproductive mode in that they lay terrestrial eggs, and the hatching larvae are collected by the male, who broods them in his vocal pouches.

Hylidae. The Hylidae (treefrogs) (40 genera, 900 species) have their diversity predominantly in South America, Central America, and tropical southern North America, with other centers of diversity in the Australo-Papuan region, and with a few species found in temperate North America, Eurasia, and North Africa. The physical, physiological, and ecological diversity of the treefrogs is enormous, with arboreal and terrestrial members. Some treefrogs have bizarre helmet-shaped skulls, and some of the leaf frogs are unique in excreting uric acid like birds. Most species have aquatic eggs and larvae, but one large radiation in South America has young that develop directly in pouches on the back; in two of those the dorsal pouches penetrate through the axial musculature into the abdominal cavity.

Centrolenidae. The glass frogs (3 genera, 135 species) are another group of treefrogs in tropical Central and South America, in areas of high-gradient streams. Many species have translucent to transparent ventral skin that allows the beating heart to be seen clearly.

Pseudidae. The paradox frogs (two genera, nine species) are a small group of aquatic hyloid frogs most likely evolutionarily within the Hylidae, but the evidence so far is meager. These frogs inhabit the tropical lowlands of South America. Aquatic eggs develop into huge tadpoles ("paradox frog" from this aspect of their life history) that transform into relatively small adult frogs.

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