A new species of Macrostemum Kolenati (Trichoptera: Hydropsychidae), with updated key to Neotropical species of the genus and new caddisfly records from Northeastern Brazil.

In this study, a new species of Macrostemum is proposed based on adult males from Pernambuco state, Brazil. The new species can be diagnosed from its congeners mainly by the segment X with apex acuminate in lateral view, having a pronounced, narrow, deep, and U-shaped incision in dorsal view, by the presence of subbasal lateral setal warts, and by the dumbbell-shaped phallotremal sclerite in dorsal view. A key of male Neotropical Macrostemum species is also presented. Additionally, we provide five new caddisfly records for the Pernambuco state (Cernotina longispina, Helicopsyche tapadas, Macronema fragile, Triplectides gracilis, and Triplectides neotropicus); two of them constitute new records for the Brazilian Northeast region (Helicopsyche tapadas and Triplectides neotropicus), with Helicopsyche tapadas being recorded for the first time in the country. [ABSTRACT FROM AUTHOR]