''Elachistocleis'' is a genus of

microhylid The Microhylidae, commonly known as narrow-mouthed frogs, are a geographically widespread family (biology), family of frogs. The 683 species are in 63 genera and 11 subfamilies, which is the largest number of genera of any frog family. Evolution ...

frog A frog is any member of a diverse and largely Carnivore, carnivorous group of short-bodied, tailless amphibians composing the order (biology), order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-f ...

s found in southern America from Panama southwards. Their common name is oval frogs, although for historic reasons not all species are named so. eb application 2013. Berkeley, California
''Elachistocleis''
AmphibiaWeb, available at http://amphibiaweb.org/. (Accessed: 29 November 2013).

Taxonomy

A 2021 study found that the genus originated in the

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

during the

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

, and contains two distinct

clades A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, t ...

that diverged from one another during the

Middle Miocene The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene. The sub-epoch lasted from 15.97 ± 0.05 Ma to 11.608 ± 0.005 Ma (million y ...

. They dispersed throughout

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

following the drying-out of the

Pebas mega-wetland system Pebas District is one of four districts of the province Mariscal Ramón Castilla in Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the St ...

, aided by the

Amazon basin The Amazon basin is the part of South America drained by the Amazon River and its tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries of Bolivi ...

and other hydrological systems. Recent taxonomic evidence indicates that the type species, '' E. ovalis'', is a ''

nomen nudum In taxonomy, a ''nomen nudum'' ('naked name'; plural ''nomina nuda'') is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published with an adequate descr ...

'', as it has no

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

, type locality, and its description lacks detail. The name has been applied to many ''Elachistocleis'' populations across South America, which are all now considered to represent

undescribed species In taxonomy, an undescribed taxon is a taxon (for example, a species) that has been discovered, but not yet formally described and named. The various Nomenclature Codes specify the requirements for a new taxon to be validly described and named. U ...

(with one of these from

Trinidad Trinidad is the larger and more populous of the two major islands of Trinidad and Tobago. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is often referred to as the southernmos ...

and northern

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

being described as '' E. nigrogularis'' in 2021). In addition, another ''Elachistocleis'' identified from Trinidad in a 1980 study likely represents another undescribed species.

Species

The following species are recognised in the genus ''Elachistocleis'':

References

Microhylidae Amphibians of Central America Amphibians of South America Amphibian genera Taxa named by Hampton Wildman Parker {{Microhylidae-stub