Temporal distribution and early development of Moenkausia cf. gracilima (Lucena & Soares, 2016) (Osteichthyes, Characidae) in the Upper Paraná River, Brazil.

Joyce Andreia Dos Santos, Joyce Andreia dos Santos, Márcia Sayuri Iquematsu, Claudemir Martins Soares, Eliana Maria Galdioli, Kleber Faria da Silva, Valmir Alves Teixeira, Andréa Bialetzki


Abstract: Aim: To characterize the early development and temporal distribution of larvae and juveniles of Moenkhausia cf. gracilima. Methods: Samples were taken quarterly in twenty-five sites in the Upper Paraná River floodplain between August 2013 and May 2015. The samples were taken under the water surface at night using 0.5 mm mesh plankton nets. In the laboratory, samples were sorted, identified and separated into larval (preflexion, flexion and postflexion) and juvenile periods. Results: A total of 248 individuals was collected; ninety-nine percent in the Saraiva Lagoon, suggesting that the entire life cycle of this species occurs in this environment, and that the reproductive period takes place between December and April, since the postflexion larvae were found until May. However, the occurrence of juveniles between February and May indicates probable batch spawning. Among the 95 individuals used for ontogenic description, 82 were larvae and 13 juveniles. Larvae may be characterized by irregular pigmentation in the upper region of the head, mouth, and body, increasing throughout development; upper lobe of the caudal fin more pigmented than the lower lobe, only visible in postflexion larvae; terminal mouth; anal opening located anterior to the median region of the body and total number of myomers ranging from 34 to 40 (15 to 20 pre and 16 to 23 postanal), while juveniles have characteristics similar to adults The total number of fin rays is: P. 11-16, V. 7-11, D, 9-11 and A. 21-23. Conclusion: Growth analysis indicated important changes in larval morphology that may be associated with the ecomorphological characteristics of the species. The morphological separation of larvae of M. cf. gracilima from other small characids, mainly in the early stages of development is difficult by the overlap of traits, suggesting the use of other variables, mainly morphometric, for the separation of species.


Fish, ichthyoplankton, ontogeny, Saraiva Lagoon.

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