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
some cases, to include terrestrial species of orders comprising both
terrestrial and aquatic taxa. In no case is a taxonomic rev1s10n of any
group undertaken, although recommendations for such revisions are
included where appropriate, and probable synonymy of nominal species
still treated as valid in the literature is noted. Two different
approaches will be employed according to the taxon being treated. For
phylogenetic groups encompassing overwhelmingly or exclusively aquatic
species, such as the orders Plecoptera 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. Where feasible, complete keys will be
prepared for groups containing both aquatic and terrestrial species that
do not encompass an extraordinarily large number of species. This has
already been done for the order Collembola.