 |
| Characidium iaquira Zanata, Ohara, Oyakawa & Dagosta, 2020 DOI: 10.1111/jfb.14485 |
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.
Keywords: Amazon, Characidium crandellii, Characidium declivirostre, Characiformes, pectoral fin
 |
| Live specimens of Characidium iaquira from rio Juruena sub basin, upper rio Tapajós basin, Mato Grosso, Brazil: (a) holotype, MZUSP 125780, 64.6 mm standard length, lateral and dorsal views; (b) paratype, MZUSP 125644, 48.4 mm standard length, lateral view. |
 |
| Aquarium specimens of Characidium iaquira |
 |
| (a) Characidium iaquira, holotype, MZUSP 125780, 64.6 mm standard length, rio Juruena sub basin, upper rio Tapajós basin, Mato Grosso, Brazil, ventral view of the anterior portion of the body. (b) Characidium cf. declivirostre, MZUSP 122324, 68.8 mm standard length, rio Juma basin, Amazonas, Brazil, ventral view of the anterior portion of the body. (c) Characidium iaquira, holotype, dorsal view of the pectoral fin, white arrow indicates swollen membrane covering basal portion of fin and black arrow indicates posteriormost rays abutting body wall. |
Characidium iaquira sp. n.
Etymology: The specific name iaquira comes from the Tupi language, meaning green (Miranda, 1942), in allusion to the remarkable iridescent green colouration of body of the species in life. A noun in apposition.
Angela M. Zanata, Willian M. Ohara, Osvaldo T. Oyakawa and Fernando C. P. Dagosta. 2020. 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. Journal of Fish Biology. DOI: 10.1111/jfb.14485
