''Stefania evansi'' is a species of

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 ...

in the family

Hemiphractidae The Hemiphractidae are a family of frogs from South and Central America. Previously, this group had been classified as a subfamily (Hemiphractinae) under family Hylidae. More recent research classifies these genera into their own family, or som ...

. ''Stefania evansi'' is, along with other closely related frogs, known for its unusual reproductive mode where females carry the eggs and juveniles on their back. It is sometimes known under common names Groete Creek carrying frog, Groete Creek treefrog, or Evans' stefania (the "treefrog" designation can be misleading as ''Stefania'' are no longer included in the family

Hylidae Hylidae is a wide-ranging family of frogs commonly referred to as " tree frogs and their allies". However, the hylids include a diversity of frog species, many of which do not live in trees, but are terrestrial or semiaquatic. Taxonomy and ...

). These names refer to its type locality, Groete Creek in the region

Essequibo Islands-West Demerara Essequibo Islands-West Demerara (Region 3) is a Regions of Guyana, region of Guyana. It is situated around the Essequibo River, the largest river in Guyana that lies between the Orinoco and Amazon River, Amazon rivers of South America. It is bor ...

Guyana Guyana, officially the Co-operative Republic of Guyana, is a country on the northern coast of South America, part of the historic British West Indies. entry "Guyana" Georgetown, Guyana, Georgetown is the capital of Guyana and is also the co ...

, where the

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 ...

was collected by one Dr. R. Evans.

Distribution and habitat

''Stefania evansi'' is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

and distributed in forested lowlands of west-central Guyana at altitudes below . Frogs collected at higher altitudes probably represent ''

Stefania scalae ''Stefania scalae'' is a species of frog in the family Hemiphractidae. It is found in Guyana, Venezuela, and possibly Brazil. Its natural habitats are subtropical or tropical moist montane forests, river A river is a natural stream of ...

'', a species that was for a while considered to be

synonymous A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

with ''Stefania evansi''. It generally occurs in habitats with low human impact and is not considered threatened.

Description

''Stefania evansi'' is one of the largest members of the genus: males grow to up to in snout–vent length and females to . ''Stefania evansi'' is dimorphic with respect to colouration: one morph is plain, and the other one is striped. A single brood can contain both morphs.

Reproduction

As is typical for the genus, female ''Stefania evansi'' carry the eggs on their back and juveniles develop fully on their mother's back. The eggs and juveniles are exposed but adhere to a mucus layer. Brood size is variable: among 11 recorded clutches, it is 11–30 eggs and increases with female size; 30 eggs is the highest brood size recorded in the genus. Eggs containing tailed, gilled larvae measure in diameter. Eggs hatch on the female's back as froglets, without a free-living larval stage. Juveniles stay on their mother's back until they are about in length, although smaller ( SVL) independent juveniles can also be found. It is speculated that the juveniles leave their mother's back when the resorption of the gill stalks is complete, coinciding with the consumption of all yolk. Juveniles may leave their mother also prematurely, showing residual gill stalks and yolk in their bellies, in response to stress caused by handling or predation. The duration of development and brooding is not known, but is assumed to require about 2–3 months. Breeding seems more frequent during—but not strictly restricted to—the rainy season.

References

{{Taxonbar, from=Q265441 Stefania Amphibians of Guyana Endemic fauna of Guyana Taxonomy articles created by Polbot Amphibians described in 1904