BackgroundDiversity and distribution of Neotropical aquatic insects is still poorly known, with many species to be recorded and many others to be described, due to the small number of taxonomists and sparse faunistic studies. This knowledge is especially poor in the Caatinga Domain in Northeastern Brazil, even though, this region may have played an important historical role in the spatial evolution of faunas of forested areas in northern South America.New informationAquatic insect checklists of 96 species from Parque Nacional de Ubajara (Ceará State, Brazil) and 112 species from Parque Nacional de Sete Cidades (Piauí State, Brazil) are presented, representing the following taxa: Elmidae, Epimetopidae, Hydrophilidae, and Torridincolidae (Coleoptera), Hemerodromiinae (Diptera: Empididae), Ephemeroptera, Gerromorpha and Nepomorpha (Hemiptera), Odonata, Plecoptera, and Trichoptera. Because of the scarce number of biological inventories in Northeastern Brazil, several new distributional records (of species, genera, and families) for Brazil, Northeastern Brazil, and Ceará and Piauí states are provided. In addition, several undescribed species were detected, being 26 from Ubajara and 20 from Sete Cidades. Results represent a significant increase to the known fauna of these states, ranging from 13%-70% increase for Ceará and 41% to 91% increase for Piauí. Although both parks are relatively close to each other and within the Caatinga domain, their aquatic fauna display a very high complementarity (89% species), possibly due to structural differences of water bodies sampled in each park. Rarefaction curves based on quantitative light trap samples suggest a much higher expected species richness of aquatic insects at Sete Cidades than at Ubajara National Park. Discussion on biogeographical affinities of this sample of the Caatinga fauna is provided.

Macrelmis is a genus distributed in the Palearctic, Nearctic and Neotropical regions. Currently there are 40 species, 20being recorded from Brazil but only two from Rio de Janeiro State. Herein two new species of Macrelmis are describedand figured: Macrelmis fluminensis sp. nov. and Macrelmis friburguensis sp. nov. A new record of Macrelmis isis from Rio de Janeiro State is given.

The genus Austrolimnius Carter & Zeck has its greatest known diversity in Oceania, but its fauna in the Americas is poorlyknown. In this paper, two new species—Austrolimnius uncatus sp. nov. and A. bocainensis sp. nov.—are described and illus-trated based on adult specimens collected at Serra da Bocaina National Park, São José do Barreiro Municipality, São PauloState, and Nova Friburgo Municipality, Rio de Janeiro State, Brazil. Austrolimnius uncatus sp. nov. is characterized by the longsetae on the mesotarsus, the medial expansion of the hind tibiae, and the hook-like shape of the male genitalia. Austrolimniusbocainensis sp. nov. can be recognized by the absence of setae on the mid-tarsus, the cylindrical hind tibiae, and the slightlycurved genitalia with few setae. A pictorial key for the Brazilian species of the genus is given. New records of Brazilian species of the genus are reported.

The genus Xenelmis is found in the Nearctic and Neotropical regions. Currently, seven out of thirteen species are registered from Brazil. Here, two new species of Xenelmis from Brazil are described and illustraded-Xenelmis sinecarina sp. nov. and Xenelmis granatoides sp. nov. Additionaly, X. granata and X. micros are characterized and illustrated.

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