Genetic evidence for two species of the genus Pimelodus Lacépède, 1803 (Siluriformes, Pimelodidae) in the Iguaçu River (Brazil)

The existence of reproductive isolation between two morphs of catfish, endemic to the Iguaçu River (Brazil), was examined by enzyme starch gel electrophoresis. Tissues of 19 catfish (Pimelodus ortmanni) and 15 of a similar morph (Pimelodus sp.), which differs from P. ortmanni by presenting larger and more scattered dusky spots on its skin, were analyzed. A Nei's (1978) genetic identity of 0.551 was determined by the analysis of 22 enzyme loci. The loci EST*1, EST*2, GDH*1, GPI*1, GPI*2, IDH*1, MDH*1, MDH*2, and PGM*1 were fixed for different alleles in each morph, that is, no heterozygote was found for these loci. The enzymatic patterns observed for the two morphs indicate both that the taxa are reproductively isolated and that they in fact represent separate species

Biochemical taxonomy of Crenicichla (Pisces: Perciformes: Cichlidae) of the Iguaçu River, Brazil

Samples of Crenicichla iguassuensis and a morph from the Iguaçu River which differed from C. iguassuensis by its lips morphology were examined by isozyme starch electrophoresis technique. The analysis of 27 enzyme loci exhibited a genetic identity of 0.993 between the two morphs. No diagnostic locus was found that permitted to distinguish the two Crenicichla morphs. The data obtained in this investigation did not support the existence of two distinct species for this genus in the Iguaçu River, which suggested that the morphs stood for two polymorphic forms of Crenicichla iguassuensis