Caracterização e distribuição de Elmidae (Insecta, Coleoptera) no Rio da Fazenda, Floresta da Tijuca, Rio de Janeiro, RJ

Abstract

ln a study carried out on Elmidae in a first order stream at Tijuca Forest, Rio de Janeiro, RJ (Brazil), samples were taken from four substrate types: litter from pools, hard rocks, sand and litter from riffles. A total of 1542 individuals, being 246 adults and 1296 larvae, of 7 species: Austrolimnius laevigatus (Grouvelle, 1889), Cylloepus sp., Gonielmis sp., Heterelmis sp., Macrelmis sp., Neoelmis sp. and Phanocerus clavicornis Sharp, 1882. All taxa were redescribed. Pertinent characters for recognition of the various taxa are illustrated. Litter from riffles showed the highest abundance per substrate and winter presented the highest abundances among seasons. Gonielmis is for the first time reported to Brazil. Based on the biomass of the most abundant species, two life cycle patterns were found. Heterelmis sp. presented smaller larvae predominating in summer and later instars appearing in winter. On the other hand, Phanocerus clavicornis presented the later instars appearing in summer and smaller larvae in winter. Apparently the main environmental variables affecting Elmidae spatial and temporal distribution were temperature and water level.