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

Abstract

Aim: To analyze temporal distribution of larvae and juveniles and the early development and 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, mainly in the Saraiva Lagoon, suggesting that the entire life cycle of this species occurs in this environment. 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. Conclusions: According to the distribution of developmental periods it is possible to conclude that this species reproduces in the summer, preferably in lagoons. Growth analysis indicated important alterations in larval morphology (metamorphosis) that may be associated with the ecomorphological characteristics of the species. The morphological separation of larvae of M. cf. gracilima from other larvae of small characids, especially at preflexion and flexion stages may be complicated by the overlap of traits, suggesting the use of other variables, mainly morphometric, for the separation of the species.

Early ontogeny of yellowtail tetra fish Astyanax lacustris (Characiformes: Characidae)

“…In the vitelline larval stage, the larvae have a large yolk sac and the eyes are developed, but without pigmentation, and the subterminal mouth is also observed but not yet open. It is possible to verify the absence of gills similar to the works of Santos et al (2017).…”

“…(1997), Bryconamericus stramineus for Galuch et al. (2003) and Moenkausia cf gracilima for Santos et al (2017).…”

“…Comparing A. lacustris to the other Characidae of the upper Paraná River basin with known initial ontogeny, it presents 32–40 myomeres, against 36–38 of Bryconamericus stramineus (Galuch et al., 2003), 32–35 of Serrasalmus spilopleura , 36–39 Serrasalmus marginatus (Cavicchioli, Nakatani, & Shibatta, 1997) and 34–40 Moenkausia cf. gracilima (Santos et al, 2017), demonstrating that this character can be one of the parameters to be used to assist in the separation of the larvae of these species in the natural environment.…”

“…Kendall, Ahlstrom, and Moser (1984) report that each species has a distinct pigmentation pattern, the size, and location of the melanophores being genetically determined. For characids, the pigmentation pattern is very similar, with the initial larvae being less pigmented than the more developed ones (Anjos & Anjos, 2006; Çelik et al., 2012; Galuch et al., 2003; Montoya, Arias, & Oliveira‐Angel, 2010; Nakatani et al., 2001; Park et al., 2014; Walter, 2012; Mattox, Hoffmann, & Hoffmann, 2014; Santos et al, 2017; Ferreira‐Marinho, 2017). However, at the end of the larval period (postflexion), A. lacustris larvae have conspicuous spots, both in the humeral region and in the caudal peduncle, similar to those found in adults, becoming an important character in the identification of individuals during their initial development.…”

“…Studies of small species are still poorly known (Anjos & Anjos, 2006; Çelik, Celik, Cirik, Gurkan, & Hayretdag, 2012; Ferreira‐Marinho, 2017; Galuch, Suiberto, Nakatani, Bialetzki, & Baumgartner, 2003; Mattox, Hoffmann, & Hoffmann, 2014; Park et al., 2014; Santos et al, 2017; Walter, 2012). However, it is an important tool for a better understanding of biology (Nakatani et al., 2001) and systematic and/or phylogenetic position of species (Assega, Birindelli, Bialetzki, & Shibatta, 2016; Ferreira Marinho, 2017; Mattox et al, 2014), as well as for studies of identification and evaluation of fishing resources (Nakatani et al., 2001) and in aquaculture production systems (Bialetzki, Garcia, & Orsi, 2016; Martinez & Bolker, 2003).…”