Updates on the taxonomy of Ilyobius nubilus (Navs, 1933) (Megaloptera: Sialidae: Sialinae) and Ilyobius brasiliensis (Navs, 1936) from southeastern Brazil.

Species of the Neotropical genus Ilyobius Enderlein, 1910 (Megaloptera: Sialidae) are rare and poorly known because adults are infrequently collected in the field and the larvae have restricted habitat in the stream, facts that make obtaining specimens difficult to access for study. Herein we redescribe the female, describe the male and the larva of Ilyobius nubilus (Navs, 1933) based on specimens collected on the coast of So Paulo State. Adults were obtained mainly by rearing larvae in laboratory condition until adult emergence.

A new species of Ilyobius Enderlein, 1910 (Megaloptera: Sialidae) from a threatened region in the Mantiqueira Mountain range (Brazil).

A new species of Ilyobius Enderlein, 1910 (Megaloptera: Sialidae) from the Brazilian Atlantic Forest is described based on male, female, and larva. Ilyobius erebus sp. nov.