Ontogenia inicial e ecologia trófica de Tatia jaracatia (Siluriformes: Auchenipteridae), do baixo Rio Iguaçu

Abstract

The objective of this study was to describe the initial ontogeny and allometric growth patterns of Tatia jaracatia, from the Iguaçu River basin, State of Paraná, Brazil. A total of 137 larvae and 12 juveniles were evaluated for morphometric, meristic and growth coefficient characters. Yolk larvae and pre-flexion larvae were not sampled. In the larvae at the flexion stage the standard length ranged from 7.5 to 9.3 mm, the number of pre-anal myomers corresponded from 7 to 9 and the post-anal from 18 to 22, with concentrated pigmentation at the upper and lateral region from the head. Post-flexion larvae present standard length ranges from 8.2 to 14.9 mm, the number of myomers ranged from pre-anal ranging from 7 to 13, and the post-anal from 18 to 24. At this stage, increased pigmentation throughout the body, with greater concentration in the dorsolateral region of the body and tail. In the juvenile period all the rays of the fins are already formed, they present light brown coloration, with spots of beige to yellowish staining on the sides of the body. The species presented a discontinuous isometric body growth with higher growth rates after the break point, represented by the post-flexion larvae. The important information obtained in this study in relation to the morphological characteristics of the species could help in the correct identification of the species in its natural environment, a task that is difficult to predict, since morphological similarities occur between family specimens and genus.