Variações morfológicas de três populações de Hoplias malabaricus (Bloch, 1794) (Ostariophysi; Characiformes; Erythrinidae) no estado do Rio de Janeiro

Abstract

Hoplias malabaricus is a fish species of the Erythrynidae family widely distributed, occuring in all large watersheds from South America which drains into Atlantic Ocean. Glaciations that occur in Pleistocene resulted in successive regressions and transgression of the sea level, and such variation gave shape to a serie of the present coastal independent drainages forming complex fluvial networks. This probably favored the spread of the aquatic biota, forming communities with populations continuously distributed, among them, Hoplias malabaricus. This species have wide distribution, sedentary habits, non-migratory behaviour and have high karyotipic variability already recorded in the current literature, which result in some confusion in its taxonomic position. These particularities make H. malabaricus a good exemple to test models of geographic morphologic variations, resultant from effects of marine vicariance transgression in the late Pleistocene. This study amis to assess eventual morphological changes in H. malabaricus in three areas close geographycally (far about 70 km from each other): the rivers Paraíba do Sul and Guandu, and Red lagoon, locvated in Marambaia Isle, all of them located in Rio de Janeiro State. A total of 39 morphological and 6 meristics characters were examined, with some of them compared to head lenght and others compared to total standard. Morphometric raw data were analysed using ANCOVA to compare for differences in regressions slopes and y-intercept. To avoid distortions associated to size effect, morphometrics raw data were transformed by using the Thorpe methodology. Means size of the characters were compared among fishes from the three areas by using ANOVA, followed by a Tukey post-hoc test. Character that showed significant differences according to ANOVA and ANCOVA were used to compare among the populations. Principal Component Analysis and Discriminant Analysis were used to determine eventual geographic patterns to separete specimens among the spatial factor. Specimens from Red Lagoon had comparatively higher head, fins size than the rivers species. Specimens from Guandu have comparatively larger fin base, while specimens from Paraiba do Sul have dorsal fin a more distal position. On the other hand, meristic characters did not separate specimens from the vii three areas. According to morphometric differences it is possible to discriminate the three groups of H. malabaricus, especially the population from Red Lagoon, and a closer proximity for populations from Guandu and Paraíba do Sul river.