''Elachistocleis'' is a genus of

microhylid The Microhylidae, commonly known as narrow-mouthed frogs, are a geographically widespread family of frogs. The 683 species are in 57 genera and 11 subfamilies. Evolution A molecular phylogenetic study by van der Meijden, et al. (2007) has estima ...

frog A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...

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 Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

during the

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

, and contains two distinct

clades In biology, a clade (), also known as a monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach to taxonomy ...

that diverged from one another during the

Middle Miocene The Middle Miocene is a sub-epoch of the Miocene epoch (geology), epoch made up of two Stage (stratigraphy), stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene. The sub-epoch lasted from 15.97 ± 0. ...

. They dispersed throughout South America following the drying-out of the Pebas mega-wetland system, aided by the

Amazon basin The Amazon basin is the part of South America drained by the Amazon River and its tributary, 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 ...

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

nomen nudum In Taxonomy (biology), 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 ...

'', as it has no

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

, 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, more populous island of the Republic of Trinidad and Tobago, the country. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is the southernmost island in ...

and northern Venezuela 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