Santa Cruz dwarf frog (Physalaemus soaresi)

Santa Cruz dwarf frog
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Santa Cruz dwarf frog fact file

Santa Cruz dwarf frog description

GenusPhysalaemus (1)

The Santa Cruz dwarf frog (Physalaemus soaresi) is a small amphibian known only from two locations in south-eastern Brazil (2). Like related Physalaemus species, it has relatively smooth skin, a rather pointed snout, and lacks webbing on the toes (3) (4). The body of the Santa Cruz dwarf frog is brownish, with a dark stripe along the sides (3).

Snout-vent length: c. 2.2 cm (2)
c. 1.05 g (2)

Santa Cruz dwarf frog biology

Very little information is available on the biology of the Santa Cruz dwarf frog. Like other Physalaemus species, it is likely to lay its eggs in a foam nest (1) (3) (4) (7), which is produced by mucus secretions from the female that are kicked into a foam by the male (7). The foam nest is laid on the surface of shallow, temporary pools (1) (7), and may be attached to those other females, creating large egg masses which are less likely to dry out (7). The males of Physalaemus species call to attract females, usually while floating in water (4).


Santa Cruz dwarf frog range

Until recently, the Santa Cruz dwarf frog was known only from a single location, at Horto Florestal de Santa Cruz, in the state of Rio de Janeiro, Brazil (1) (5) (6). However, it was recently recorded at a second location, at Serra do Mendanha, in Rio de Janeiro state. This species had also previously been collected from another area at Barro Branco, but is now believed to be extinct there (2).


Santa Cruz dwarf frog habitat

The Santa Cruz dwarf frog inhabits the Atlantic forest region of Brazil. It is thought to have originally occurred in primary forest, but extensive habitat destruction means it is now found only in disturbed, secondary forest (1) (2).

Santa Cruz dwarf frogs are usually found near ponds within forest, and have been recorded at elevations close to sea level and at around 130 metres above sea level (1) (2).


Santa Cruz dwarf frog status

The Santa Cruz dwarf frog is classified as Endangered (EN) on the IUCN Red List (1).

IUCN Red List species status – Endangered


Santa Cruz dwarf frog threats

The Santa Cruz dwarf frog has a small population and a very limited range, and is currently threatened by habitat loss (1) (2). The Atlantic forest of Brazil has been largely destroyed by deforestation, agriculture, plantations, urbanisation, infrastructure development and wildfires (6) (8), and Brazil’s amphibians may also face threats from disease, invasive species and climate change (6) (9).

In addition to various forms of human disturbance, such as urban expansion, the forests inhabited by the Santa Cruz dwarf frog are being converted to eucalyptus plantations and to agriculture (1) (2). This species is listed as Endangered on the list of threatened Brazilian fauna (10).


Santa Cruz dwarf frog conservation

The Santa Cruz dwarf frog is found in the Florestal Nacional Mario Xavier protected area, but this site needs improved management and protection (1). The new location at which this species was found is partially within the Parque Natural Municipal da Serra do Mendanha, but the areas the Santa Cruz dwarf frog probably inhabits are still under threat (2).

Recommendations for the conservation of Brazil’s amphibian species include better habitat protection, environmental education, captive breeding programmes and further research (6). More information may be needed on the distribution, biology and ecology of the Santa Cruz dwarf frog before more specific conservation action can be taken for this little-known amphibian.


Find out more

Find out more about conservation in the Atlantic forest:



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Atlantic forest
A highly biodiverse region found along the east coast of South America, comprising several different vegetation types, including high-altitude grassland, and lowland and montane forest.
Primary forest
Forest that has remained undisturbed for a long time and has reached a mature condition.
Secondary forest
Forest that has re-grown after a major disturbance, such as fire or timber harvest, but has not yet reached the mature state of primary forest.


  1. IUCN Red List (January, 2011)
  2. Pontes, J.A.L., Pontes, R.C., Santa-Fé, C.P., Lima, V.M. and Rocha, C.F.D. (2010) Amphibia, Anura, Leiuperidae, Physalaemus soaresi Izecksohn, 1965: New record, distribution extension and geographic distribution map. Check List, 6(1): 159-161.
  3. Nascimento, L.B., Caramaschi, U. and Cruz, C.A.G. (2005) Taxonomic review of the species groups of the genus Physalaemus Fitzinger, 1826 with revalidation of the genera Engystomops Jiménez-da-la-Espada, 1872 and Eupemphix Steindachner, 1863 (Amphibia, Anura, Leptodactylidae). Arquivos do Museu Nacional, Rio de Janeiro, 63(2): 297-320.
  4. Lynch, J.D. (1970) Systematic status of the American leptodactylid frog genera Engystomops, Eupemphix, and Physalaemus. Copeia, 1970(3): 488-496.
  5. Frost, D.R. (2011) Amphibian Species of the World: An Online Reference. American Museum of Natural History, New York. Available at:
  6. Silvano, D.L. and Segalla, M.V. (2005) Conservation of Brazilian amphibians. Conservation Biology, 19(3): 653-658.
  7. Wells, K.D. (2007) The Ecology and Behavior of Amphibians. University of Chicago Press, Chicago.
  8. Conservation International: Biodiversity Hotspots - Atlantic Forest (January, 2011)
  9. Gascon, C., Collins, J.P., Moore, R.D., Church, D.R., McKay, J.E. and Mendelson III, J.R. (2007) Amphibian Conservation Action Plan. IUCN/SSC Amphibian Specialist Group, Gland, Switzerland and Cambridge, UK. Available at:
  10. Ministério do Meio Ambiente (2003) Lista das Espécies da Fauna Brasileira Ameaçadas de Extinção. IBAMA, Brasil. Available at:

Image credit

Santa Cruz dwarf frog  
Santa Cruz dwarf frog

© Ivan Sazima

Ivan Sazima
Museu de Zoologia
Caixa Postal 6109
Universidade Estadual de Campinas
13083-970 Campinas
São Paulo


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