Fauna cavernícola brasileira: composição e caracterização preliminar

Abstract

In this study a number of caves from various Brazilian limestone regions were surveyed. The information gathered expands and improves that of our preliminary article, allowing a reasonable good picture of the Brazilian cave fauna. There doesn't seem to be any striking difference between the composition of the Brazilian cave fauna and that of the other tropical regions that have been studied. Animals commonly found throughout the studied area include: Phalangopsidae crickets, Reduviidae heteropterans, Polydesmida and Juliformida millipedes, Opilionida Laniatores, and spiders, particularly Scytodidae, Ctenidae, Theridiosomatidae and Pholcidae. Among the vertebrates the commonest are barts and catfishes. Amblypygi are common in all regions except Sao Paulo State, which is outside the group geographical distribution. Cockroaches are frequent in the warm caves to the north of Vale do Ribeira (Sao Paulo State) where these animals are rarely seen. The cave fauna of the Vale do Ribeira is better Known than that of other Brazilian regions. Those small secretive species often found in Vale do Ribeira are probable also common elsewhere: beetles (partilarly the Carabidae, Leiodidae Catopinae, and, to a lesser exyent, the Pselaphidae and Otilodactylidae); dipterans (in special Chironomidae and Keroplatidae); and typically soil animals like collembolans and earthwormos. The sandstone cave fauna is basically the same found in limestone. The only difference seems to be the larger amount of batguano found in the former, conditioning larger populations of guano-feeding arthropods such as crickets and juliformid millipedes. The fauna of the entrance and twilight zone is characterized by the predominance of the Arachnida like opilionids Goniosominae and spiders Pholcidae, and heteropterans Reduviidae; the only typical dipteran of this fauna is the larval form of the fungus gnat Neoditomyia sp. (Mycetophiloidea). It was also observed a stratification within the studied cave communities as a result of the preference of various species toward determined substrates. As in other tropical regions, terrestrial predator troglobites are rare in Brazil, in contrast with temperate caves, characterized by a larger number of such species (particularly among the spiders and beetles). For Brazil only a genus of carabid beetle (Schizogenius spp ), an unidentified species of pselaphidae beetle and some pseudoscorpions, among the terrestrial predators, have been found bearing troglomorphic characters. The Brazilian troglobites are mainly aquatic organisms (catfishes and crustaceans) or terrestrial detritivores/omnivores like isopods and polydesmide millipeds.