Wednesday 4 October 2017

Scinax onca: A new species of Treefrog from Brazil.

Treefrogs of the genus Scinax are found from from Mexico in the North to central Argentina and Uruguay in the South. Over 70 species of this genus have been described,including 28 species from Amazonia, making it one of the largest genera of Treefrogs, with many undescribed species still thought to be present in less well explored areas. One such area is the Purus-Madeira Interfluve (area between the Purus and Madiera rivers, both tributaries of the Amazon), of Amazonas State in Brazil, where seven putative undescribed species are thought to be present. This area is currently crossed by an abandoned section of highway, though there have been recent plans to redevelop this road, raising concerns about logging and habitat loss, a major cause of species decline and loss for a variety of groups, including Treefrogs.

In a paper published in the journal ZooKeys on 4 October 2017, Miquéias Ferrão of the Programa de Pós-Graduação em Ecologia at the Instituto Nacional de Pesquisas da Amazônia, Jiří Moravec of the Department of Zoology at the National Museum in Prague, Rafael de Fraga, also of the Programa de Pós-Graduação em Ecologia at the Instituto Nacional de Pesquisas da Amazônia, Alexandre Pinheiro de Almeida of the Programa de Pós-Graduação em Zoologia at the Universidade Federal do Amazonas, Igor Luis Kaefer of the Instituto de Ciências Biológicas, also at the Universidade Federal do Amazonas, and Albertina Pimentel Lima of the Coordenação de Biodiversidade at the Instituto Nacional de Pesquisas da Amazônia, describe a new species of Scinax from the middle to southern part of the Purus-Madeira Interfluve.

The new species is named Scinax onca, where 'onca' refers to the Jaguar, Pantera onca, which was encountered numerous times during fieldwork in the Purus-Madeira Interfluve, and to the blotchy pattern of the species. Females of the species are larger than the males, reaching 35.5−40.4 mm, compared to 31.3−34.5 mm, and are variable in colouration, though generally brown and blotchy, and in addition are capable of changing colour to some extent, generally becoming darker and more blotchy when disturbed.

Colour in life of Scinax onca from the Purus-Madeira Interfluve, Brazilian Amazonia. (A)–(B), adult male from the kilometre 350 of the BR-319 highway, State of Amazonas, (C)–(D) adult female from municipality of Porto Velho, State of Rondônia, (E)–(F) adult female from the Floresta Estadual Tapauá Reserve, municipality of Tapauá, State of Amazonas. Photographs (A)–(D) and (F) were taken after transport of the specimens to the camp, while the image of (E) was taken immediately in the field. Ferrão et al. (2017).

The species was found at four localities, two in areas of closed forest with emergent trees (taller trees that rise above the tree canopy) in the central part of the Interfluve and two areas of open lowland rainforest with frequent Palm Trees in the southern part. They were encountered near temporary ponds following periods of heavy rain, where the males gathered on nearby plants to sing. Tadpoles of the species are ovoid in dorsal view, triangular in lateral view, and silvery-green in colour with large dark brown spots.

 Tadpole of Scinax onca from the middle Purus-Madeira Interfluve. Specimen collected at kilometre 350 of the BR-319 highway, municipality of Beruri, State of Amazonas, Brazil. From top to bottom: dorsal, ventral, and lateral views of preserved tadpole in developmental Stage 37. Scale bar 5 mm. Ferrão et al. (2017).

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