A new rheophilic South American darter (Crenuchidae: Characidium) from the rio Juruena basin,Brazil, with comments on morphological adaptations to life in fast-flowing waters |
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| Authors: | Angela M Zanata Willian M Ohara Osvaldo T Oyakawa Fernando C P Dagosta |
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| Institution: | 1. Instituto de Biologia, Universidade Federal da Bahia, Salvador, Brazil;2. Departamento de Engenharia de Pesca, Universidade Federal de Rondônia, Presidente Médici, Brazil;3. Laboratório de Ictiologia, Museu de Zoologia da Universidade de São Paulo, São Paulo, Brazil;4. Faculdade de Ciências Biológicas e Ambientais, Universidade Federal da Grande Dourados, Dourados, Brazil |
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| Abstract: | Characidium iaquira, a new species from the upper rio Juruena, rio Tapajós basin, Brazil, is described. The new species can be promptly distinguished from all congeners by having a unique v-shaped dark mark lying along the caudal-fin extension, in medium- and large-sized specimens, and a remarkable iridescent green colouration in life. Characidium iaquira is closely related to Characidium crandellii and Characidium declivirostre by sharing unambiguous synapomorphies such as branchiostegal membranes united to each other across the isthmus, a scaleless area extending from the isthmus to the pectoral girdle, and dermal flaps surrounding anterior and posterior naris independent, but touching each other distally. Morphological specializations of the paired fins in the three riffle-dwellers species are discussed, including the wing-like shape, robustness, and inclination of the pectoral fin. |
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| Keywords: | Amazon Characidium crandellii Characidium declivirostre Characiformes pectoral fin |
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