Leptodactylidae

• 1. Introduction

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  The Leptodactylidae carry a name built from Greek words meaning a bird or other animal with slender toes. They are the southern frogs, a family scattered across Mexico, the Caribbean, and Central and South America. There are 206 species among them, sorted into 13 genera. Some of these frogs burrow into the ground. Others swim, others climb trees, and others live their whole lives on land. A few build nests out of foam. So how did a single family come to fill so many different kinds of homes? Why has its very definition kept shifting in recent years? And what does a frog that hatches into a foam nest do while it waits to grow up?

• 2. Slender Toes, Many Homes

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  The southern frogs most likely split from other hyloids during the Cretaceous, branching off into their own deep lineage. From that ancient divergence came a family that refused to settle on one way of living. Its members include terrestrial frogs that stay on the ground and burrowing frogs that work into the soil. The family also holds aquatic frogs suited to water and arboreal frogs that climb. Each of these forms inhabits a wide range of habitats, so the family spreads across many distinct environments rather than clustering in one. That spread reaches from Mexico down through Central and South America, with a presence in the Caribbean as well. The breadth of these living arrangements raises a separate puzzle, one about how the family is counted and named.

• 3. A Family Redrawn

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  Recent years brought major taxonomic revisions to the Leptodactylidae, reshaping where its borders fall. The most consequential change moved the former subfamily Eleutherodactylinae out entirely, reclassifying it into its own family, the Eleutherodactylidae. After that split, the Leptodactylidae settled at 206 species across 13 genera. As of December 2019, the Amphibian Species of the World sorts those genera into three subfamilies. The largest is Leptodactylinae Werner, 1896, with 96 species, holding genera such as Leptodactylus Fitzinger, 1826 and Adenomera Steindachner, 1867. Close behind is Leiuperinae Bonaparte, 1850, with 90 species, including Physalaemus Fitzinger, 1826 and Pleurodema Tschudi, 1838. Smallest is Paratelmatobiinae Ohler and Dubois, 2012, with 13 species, among them Crossodactylodes Cochran, 1938 and Rupirana Heyer, 1999. One form sits outside all three, listed as incertae sedis: the frog catalogued as "Leptodactylus" ochraceus Lutz, 1930.

• 4. Nests Of Foam

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  Several genera within the Leptodactylidae lay their eggs in foam nests, a habit that sets them apart. These nests turn up in crevices, on the surface of water, and on forest floors. Among all frogs, the foam nests of this family are some of the most varied. The placement of the nest shapes what happens next for the young. When eggs hatch in a nest resting on the forest floor, the tadpoles stay put inside it. They do not eat during this time, waiting within the nest until metamorphosis transforms them. That patience inside a froth of foam is one of the quieter strategies in a family already known for its range, and the same family has left traces far older than any living nest.

• 5. Traces In Stone

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  Fossils of Leptodactylidae have been found in Maastrichtian India, a record carried in rock rather than in living populations. The Maastrichtian belongs to the close of the Cretaceous, the same broad era when the family most likely diverged from other hyloids. That a southern frog family should leave fossils in India points to a distribution in the deep past unlike its modern spread across the Americas. The living frogs cluster in Mexico, the Caribbean, and Central and South America today. The stone, by contrast, remembers them somewhere else entirely.