Diversidade dos characiformes (osteichthyes, ostariophysi) do rio Guamá

Abstract

The Guamá River presents favorable conditions for high biodiversity along its 700 km length, from its headwaters at Serra do Coroados to its mouth in the Guajará Bay. This subproject aims to elaborate an inventory of the fish fauna of the river and its tributaries, and to comment descriptively on the taxonomic groups of the Characiformes order (e.g, The material was collected in the region of Ourérn, in the middle course of the river, using nets and puçás, and then fixed in 10% formalin and preserved in 70% ethanol. The variation in the water level of the river between the dry and flood seasons considerably modifies the composition of the fauna. A total of approximately 3500 individuals were examined, and of these at least 60% belonged to the order Characiformes. The families with the highest representation were Characidae and Curimatidae. The families Anostomidae, Lebiasinidae, Chilodontidae, Erythrinidae, Hemiodontidae, and Ctenoluciidae were much less populated. Among the caracids, the subfamily Tetragonopterinae showed the highest number of species, with at least four significant genera: Moenkhausia, Hyphessobrycon, Astyanax, and Bryconops. In terms of numbers of individuals per taxonomic group, the Curimatidae indicated greater representativeness: at least three genera were identified from them: Cyphocharax, Psectrogaster, Steindachnerina. A new occurrence was also registered for the species Cyphocharax spilurus, previously mentioned only in the Guianas and Rio Branco. A functional key for the identification of Characiformes of the region was developed using morphometric and meristic measurements, dental formula (size, number and shape of teeth) and color patterns.