Vitreorana eurygnatha is a small glass-frog (SVL 17-23 mm). The snout is rounded, short and truncated, not spatulated, lacking an upper lip ridge, nostrils near terminal; vomerine teeth are absent. Eyes directed forward, and prominently elevated. The tympanum is usually partially hidden to almost entirely hidden, diameter about 1/2 eye diameter. A single vocal sac, males with vocal slits. The finger and toe discs are large, truncate or rounded-truncate, and larger than tympanum; glandular pad on inner side of thumb. Dorsal texture smooth or very finely granular with regularly spaced pigment cells; belly smooth with transparent ventral skin through which the internal organs are visible. Tarsal fold is absent. Cloacal flap rather broad, notched mesially, flanked behind by indefinite, flattened, cloacal pads, with some few enlarged granules on ventral surface. The bones are green in life (Taylor and Cochran 1955; Heyer 1978; Heyer et al. 1990; Cisneros-Heredia and McDiarmid 2007). Cisneros-Heredia and McDiarmid (2007) provided a brief description of the internal morphology.
The larval oral apparatus is anteroventral, oral disc with a single row of marginal papillae, without denticles. The body is ovoid in dorsal view with a narrow and muscled tail, almost 2 times and a half the body length. Fins low, dorsal fin origin at the body-tail juncture. The eyes and nostrils are dorsal and very small. Spiracle sinistral, mid-way on side, extremely posterior almost at the end of the body. Length at Gosner stage 42: 50.4 mm. The color in life varies from light red to yellowish (Heyer 1985; Altig and McDiarmid 1999).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Brazil
The species is distributed along the Atlantic Rain Forest in the Serra do Mar and Serra da Mantiqueira in the States of Bahia, Espírito Santo, Rio de Janeiro, eastern Minas Gerais, São Paulo, Parana and Santa Catarina, in eastern Brazil, above 1,700 m. Vitreorana eurygnatha lives associated with forest streams on primary forests (Heyer 1985; Freitas et al. 2004, 2007).
Life History, Abundance, Activity, and Special Behaviors
Vitreorana eurygnatha lives inside forests near small streams (usually 1-2 m in wide). Males call at night on low vegetation and shrubs in the rainy season from August to January (Heyer et al. 1990; Haddad and Sazima 1992; Ribeiro et al. 2005). The advertisement call was described by Heyer et al. (1990) and can be heard in Haddad et al. (2003). The call is given sporadically; call duration 0.04-0.1 s.This species lays a few eggs directly on the surface of leaves hanging above swift streams. On hatching, the tadpoles fall into the streams where they complete metamorphosis (mode 25 of Haddad and Prado, 2005; Izecksohn and Carvalho-e-Silva 2001). The adults frequently occur at low densities, usually one or two per linear meter of stream (Heyer et al. 1988; pers. obs).
The tadpoles typically live in brooks where they are found burrowing in the leaf litter, mud, sticks and sand at the stream bottom, usually near turbulent waters (Haddad and Sazima 1992).
Trends and Threats
Its range is within protected areas, like the Parque Estadual Nova Baden, at Lambari-MG, Parque Estadual de Ibitipoca, at Lima Duarte-MG, Parque Nacional da Serra da Bocaina, São José do Barreiro-SP, Parque Estadual da Serra do Mar, Ubatuba-SP, Parque Nacional da Tijuca, in Rio de Janeiro-RJ. There are reports of population decline of H. eurygnathum in several mountain environments in southeastern Brazil, including the Serra do Japi, the Estación Biologica de Boracéia, Santa Teresa and Tijuca, where this species has not been seen since the 1980s. These declines are likely due to pollution and/or drastic climate changes (Heyer et al. 1988; Weygoldt 1989; Izecksohn and Carvalho-e-Silva 2001; Eterovick et al. 2005), but recent analysis did not detect infection by the fungus Batrachochytrium dendrobatidis (Carnaval et al. 2006).
Possible reasons for amphibian decline
General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Drainage of habitat
Subtle changes to necessary specialized habitat
Long-distance pesticides, toxins, and pollutants
Climate change, increased UVB or increased sensitivity to it, etc.
The epithet eurygnathum probably comes from the junction of two greek words: eurus, meaning "wide" and gnathos, meaning "jaw" or "mouth", that is, wide mouth.
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Bergallo, H. G., Rocha, C. F. D., Alves, M., and Van Sluys, M. (2000). A Fauna Ameaçada de Extinção do Estado do Rio de Janeiro. Faperj and UERJ Press, Rio de Janeiro.
Carnaval, A. C. O. de Q., Puschendorf, R., Peixoto, O. L., Verdade, V. K., and Rodrigues, M. T. (2006). ''Amphibian chytrid fungus broadly distributed in the Brazilian Atlantic rain forest.'' EcoHealth, 3(1), 41-48.
Cisneros-Heredia, D. F., and McDiarmid, R. W. (2007). ''Revision of the characters of Centrolenidae (Amphibia: Anura: Athesphatanura), with comments on its taxonomy and the description of new taxa of glassfrogs.'' Zootaxa, 1572, 1-82.
Eterovick, P. C., Carnaval, A. C. O. Q., Borges-Nojosa, D. M., Silvano, D. L., Segalla, M. V., and Sazima, I. (2005). ''Amphibian declines in Brazil: an overview.'' Biotropica, 37(2), 166-179.
Freitas, M. A., Silva, T. F. S., and Argôlo, A. J. S. (2004). ''Geographic distribution. Hyalinobatrachium eurygnathum (Rio Glass Frog).'' Herpetological Review, 35, 281.
Freitas, M. A., Silva, T. F. S., and Fonseca, P. (2007). ''Geographic distribution Hyalinobathrachium eurygnathum. Amargosa, Bahia.'' Herpetological Review, 38, 475-476.
Haddad, C. F. B., Giovanelli, J. G. R., Giasson, L. O. M., and Toledo, L. F. (2005). Guia sonoro dos anfíbios anuros da Mata Atlântica (Sound guide of the Atlantic rain forest anurans). Audio CD. NovoDisc Mídia Digital da Amazônia, Manaus.
Haddad, C. F. B., and Prado, C. P. A. (2005). ''Reproductive modes in frogs and their unexpected diversity in the Atlantic Forest of Brazil.'' BioScience, 55, 207-217.
Haddad, C. F. B., and Sazima, I. (1992). ''Anfíbios anuros da Serra do Japi.'' História Natural da Serra do Japi: Ecologia e Preservação de uma Área Florestal no Sudeste do Brasil. P. C. Morellato, eds., Unicamp, Campinas.
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Izecksohn, E., and Carvalho-e-Silva, S. P. (2001). Anfíbios do Município do Rio de Janeiro. Editora UFRJ, Rio de Janeiro.
Ribeiro, R. S., Egito, G. T. B. T., and Haddad, C. F. B. (2005). ''Chave de identificação: anfíbios anuros da vertente de Jundiaí da Serra do Japi, Estado de São Paulo.'' Biota Neotropica, 5(2), 235-247.
Ruiz-Carranza, P.M. and Lynch, J.D. (1991). ''Ranas Centrolenidae de Colombia I: Propuesta de una nueva clasificación genérica.'' Lozanía, (57), 1-30.
Taylor, E.H., and Cochran, D.M. (1953). ''Frogs of the family Centrolenidae from Brasil.'' The University of Kansas Science Bulletin, 35, 1625-1656.
Weygoldt, P. (1989). ''Changes in the composition of mountain stream frog communities in the Atlantic Mountains of Brazil: Frogs as indicators of environmental deteriorations?'' Studies on Neotropical Fauna and Environment, 24, 249-255.
Written by Diogo Borges Provete (dbprovete AT gmail.com), Department of Zoology and Botany, Universidade Estadual Paulista, campus São José do Rio Preto-SP, Brasil
First submitted 2008-09-12
Edited by Keith Lui (2009-06-24)
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