This work was begun to provide keys to the aquatic insect species known
from Brazil. The original goal was to include all genera known from
South America and all species from Brazil, but for most groups, the
scope was expanded to encompass all species in South America, and, in
many cases, to include terrestrial species of orders that include both
terrestrial and aquatic taxa. In no case is a taxonomic reVlSlon of any
group undertaken, although recommendations for such revisions are
included, and the probable synonymy of nominal species still treated as
valid in the literature is noted. Two different approaches are employed
according to the taxon being treated. For phylogenetic groups
encompassing overwhelmingly or exclusively aquatic species, such as the
orders Odonata and Ephemeroptera or the families Dytiscidae and
Culicidae, keys are provided to distinguish all genera and species known
to occur in South America. An effort has been made to include every
identifiable species so that the user of the key can determine with
reasonable certainty whether or not his specimen belongs to a species
that has already been described or whether it is one that is not yet
known to science.