The ichthyofauna from Presidente Olegário Karst area, Minas Gerais state, with emphasis on subterranean species

Abstract

Ichthyofauna from the karstic area of Presidente Olegário, north-central of Minas Gerais state, was studied on several occasions (two epigean streams and three caves), showing a moderate richness: 12 species recorded, distributed on Characiformes, Siluriformes and Cyprinodontiformes orders. Two species were recorded cohabiting the same subterranean stream, however, both are non-troglomorphic: the small catfish Trichomycterus brasiliensis and the small armoured catfish Parotocinclus sp.; the first one also occupying a reach of a vadose tributary from Vereda da Palha cave. The occurrence of individuals of different ranges of body size/age indicates that they are completing their life cycles in the hypogean realm, and are possibly troglophilic fishes (species able to live and complete their life cycle in the epigean and subterranean relams). Indeed, for Parotocinclus species was recorded a population variability for melanic pigmentation, which can represent an early stage of isolation and differentiation in the subterranean environment.