Vitreorana uranoscopa is a small glass-frog (SVL 19,5 - 25,8 mm). The snout in dorsal view is rounded and spatulate, truncated in lateral view; upper lip with a dermal ridge; vomerine teeth are absent. Eyes directed forward, latero-dorsally located. Nostrils almost terminal. The small tympanum is covered above, distinct below, diameter about ï¿½ eye diameter. Males with a single vocal sac, and vocal slits. The finger and toe discs are truncate and larger than tympanum; glandular pad on inner side of thumb. Subarticular tubercles distinct and single. A small inner metatarsal tubercle. Distinct forearm fold, shallowly scalloped or not. Dorsal texture smooth or very weakly granular; belly smooth with transparent ventral skin through which the internal organs are visible. Intricate ornamentation involving enameled tubercles, folds, and crenulated flaps. The bones are green in life (Taylor and Cochran 1955; Cei 1980; Heyer 1985; Heyer et al. 1990; Cisneros-Heredia and McDiarmid 2007). Cisneros-Heredia and McDiarmid (2007) provided a brief overview of the internal morphology.
The tadpoles are typical of those from brooks, where they are found burrowing in the leaf litter, mud, sticks and sand at the stream bottom, usually near turbulent waters. The oral apparatus is anteroventral, oral disc emarginate, LTRF 2(2)/2, 2(2)/2(1) or 2(2)/3, denticles very small, rows often incomplete. Single row of papillae. The body is ovoid in dorsal view with a narrow and muscled tail. Fins low, dorsal fin originates at the body-tail juncture. The eyes and nostrils are dorsal and very small. Spiracle sinistral, mid-way on side, posterior about 4/5 distance on side. Length at Gosner stage 41: 46.7 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
V. uranoscopa lives associated with low flowing forest streams (or near waterfalls) on primary forests, and is less commonly found on secondary growth and forest edges. The species is distributed along the Atlantic Rain Forest (Semi-deciduous Atlantic Forest, Floresta Ombrï¿½fila Mista and in the Floresta Ombrï¿½fila Densa) in the Serra do Mar and Serra da Mantiqueira in the States of Espï¿½rito Santo, Rio de Janeiro, Minas Gerais, Sï¿½o Paulo, Paranï¿½, Santa Catarina, and Rio Grande do Sul in eastern Brazil, and in the provincia de Missiones in Argentina up to 1,200 m (Heyer 1985; Carvalho-e-Silva et al. 2008).
Known from eastern Brazil, along eastern Sï¿½o Paulo, Espï¿½rito Santo, Rio de Janeiro, eastern Minas Gerais, Paranï¿½, Santa Catarina and Rio Grande do Sul reaching northern Provincia de Missiones, in Argentina.
Life History, Abundance, Activity, and Special Behaviors
Vitreorana uranoscopa is found in forests near small to moderate streams with rocky bottoms. The adults frequently occur at low densities, usually one per 500m of stream, with a peak abundance of four calling males (Canelas and Bertoluci 2007). Lucas et al. (2008) recorded five individuals in the reproductive season along 100 m of a forest stream in central Rio Grande do Sul. Hartmann et al. (2005) reported visual signaling in this frog. Males performed limb lifting, apparently used to defend territory, then avoiding physical combat, as seen in other taxa of glass-frogs. Males call at night on low vegetation (from 150 cm up to 2.5 m above ground) and shrubs in the rainy season from August to January (Heyer et al. 1990); or November to March, according to Canelas and Bertoluci (2007), who noticed a pronounced peak in breeding in December (Cerezoli 2008) and inferred that this species is an explosive breeder. The advertisement call was described by Heyer (1985) and can be heard in Haddad et al. (2003). The call is given sporadically; call duration 0.04-0.1 s. Dominant frequency between 4500-5000 Hz, 3-6 pulses per note.
This species lays a single layer of a few eggs (often 29-32) directly on the upper surface of leaves hanging above streams. Upon hatching, the tadpoles fall into streams where they continue development (Mode 25 of Haddad and Prado 2005; Izecksohn and Carvalho-e-Silva 2001).
V. uranoscopa and H. eurygnathum co-occur in two localities of southeastern Brazil, but according to Heyer (1985) there is a divergence in habitat use between these frogs: H. eurygnathum is found in narrow streams and rivulets, while V. uranoscopa is found in wider ones. This suggestion remains to be confirmed.
Trends and Threats
Its range is within protected areas, like Parque Nacional da Serra da Bocaina, Sï¿½o Josï¿½ do Barreiro-SP, Parque Estadual da Serra do Mar, Ubatuba-SP, Parque Estadual de Caetetus, at Gï¿½lia-SP, Parque Nacional da Tijuca, at Rio de Janeiro-RJ, Reserva do Patrimï¿½nio Natural Serra do Caraï¿½a, at Catas Altas-MG, Reserva Rio das Pedra, at Mangaratiba-RJ, RPPN Salto Morato, at Guaraqueï¿½aba-PR, Parque Estadual Mata dos Godoy, and at Londrina-PR, Floresta Nacional de Chapecï¿½, at Chapecï¿½-SC. Recent analysis did not detect infection by the fungus Batrachochytrium dendrobatidis (Carnaval et al. 2006). There are reports of population declines in the surroundings of Rio de Janeiro (Izecksohn and Carvalho-e-Silva 2001), but there were not continuous surveys in the area, and this information may not reflect the real situation (Eterovick et al. 2005).
Possible reasons for amphibian decline
General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Dams changing river flow and/or covering habitat
Subtle changes to necessary specialized habitat
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Canelas, M. A. S., and Bertoluci, J. (2007). ''Anurans of the Serra do Caraça, southeastern Brazil: species composition and phenological patterns of calling activity.'' Iheringia, 97, 21-26.
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Lucas, E.M. and Fortes, V.B. (2008). ''Frog diversity in the Floresta Nacional de Chapecó, Atlantic Forest of southern Brazil.'' Biota Neotropica, 8(3), 51-61.
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.
Originally submitted by: Diogo B. Provete (first posted 2009-01-10)
Edited by: Keith Lui (2010-05-16)
Species Account Citation: AmphibiaWeb 2010 Vitreorana uranoscopa: Humboldt's Glass Frog <https://amphibiaweb.org/species/1829> University of California, Berkeley, CA, USA. Accessed Mar 20, 2023.
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Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 20 Mar 2023.
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