Description Males are approximately 30 mm long and females are slightly larger. The skin of the túngara frog is brown and pustular, giving it a toadlike appearance that is reflected in its scientific name (Ryan 1985).
No teeth are present on the maxilla and premaxilla; tubercles are present on the dorsum in a variable pattern that may include large tubercles in longitudinal rows, chevrons, or both large and small tubercles randomly scattered (Cannatella and Duellman 1984). It also has a tuberculate tympanic membrane and the first finger is longer than the second.
Mexico to Colombia and Venezuela, generally in lowland areas (up to 1,540 m asl) (Santos-Barrera et al. 2008). Found in savannahs as well as both natural and disturbed humid lowland and montane forest, tropical dry forest, and open environments such as pastures. Can tolerate secondary growth and forest edges. Often found near ponds, both natural and man-made. It also makes use of smaller bodies of water such as ditches, puddles, and potholes.
Life History, Abundance, Activity, and Special Behaviors Engystomops pustulosus lays its eggs in foam nests, generally under cover, in pools. The foam nests are believed to prevent egg desiccation during brief periods without rain (Ryan 1985).
Laying eggs under cover may help avoid predation (Tarano 1998). Eggs are laid in a variety of habitats, including disturbed areas.
However, pond use is correlated with proximity to other ponds, making this species vulnerable to habitat fragmentation (Marsh et al. 1999).
Males call at night while floating in the water. The call has two components: a whine and 0-6 chucks. Studies show that females prefer the calls with the chucks incorporated, but males of this species are preyed upon by the fringe-lipped bat (Trachops cirrhosus) which homes in on the chucks, providing an interesting case of sexual selection opposing natural selection (Ryan 1985).
Trends and Threats This species is generally quite common in Central and South America and can occupy diverse habitats, including disturbed ones. It is not common in Belize or in southwestern Campeche, Mexico. It does not seem to be currently threatened. Its range overlaps with a number of protected areas (Santos-Barrera et al. 2008).
Comments Can frogs with foam nests help make biofuels? The long-lasting foam nests of the Túngara frog (Engystomops pustulosus) help protect its tadpoles. Now a team of researchers has designed a novel artificial photosynthesis system suspended in a foam, using the Túngara frog surfactant protein Ranaspumin-2. The system could produce up to 10-fold more biofuel per hectare than plants and could be used on rooftops and nonarable land (Wendell et al. 2010).
Cannatella, D.C. and Duellman, W.E. (1984). ''Leptodactylid frogs of the Physalaemus pustulosus group.'' Copeia, 1984(4), 902-921.
Marsh, D.M., Fegraus, E.H., and Harrison, S. (1999). ''Effects of breeding pond isolation on the spatial and temporal dynamics of pond use by the Tungara Frog, Physalaemus pustulosus.'' Journal of Animal Ecology, 68, 804-814.
Ryan, M.J. (1985). The Túngara Frog: A Study in Sexual Selection and Communication. University of Chicago Press, Chicago.
Ryan, M.J., Rand, A.S., and Weigt, L.A. (1996). ''Allozyme and advertisement call variation in the Tungara frog, Physalaemus pustulosus.'' Evolution, 50(6), 2435-2453.
Santos-Barrera, G., Solís, F., Ibáñez, R., Wilson, L. D., Savage, J., Bolaños, F., Lee, J., Chaves, G., Señaris, C., Acosta-Galvis, A., and Hardy, J. 2008. Engystomops pustulosus. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.1. www.iucnredlist.org. Downloaded on 29 March 2010.
Tárano, Z. (1998). ''Cover and ambient light influence nesting preferences in the Túngara Frog Physalaemus pustulosus.'' Copeia, 1998(1), 250-251.
Wendell, D., Todd, J., and Montemagno, C. (2010). ''Artificial photosynthesis in ranaspumin-2 based foam.'' Nano Letters, DOI: 10.1021/nl100550k.
Written by Michelle Knapp (mknapp AT fas.harvard.edu), Harvard University First submitted 2003-01-09 Edited by Kellie Whittaker (2010-03-29)