Two new species of Sminthurididae (Hexapoda, Collembola, Symphypleona) from Brazil with notes on Denisiella Folsom & Mills and Sphaeridia Linnaniemi

Two new species of Sminthurididae, Sphaeridiapiauiensis Medeiros & Bellini, sp. nov. and Denisiellapiracurucaensis Silva, Medeiros & Bellini, sp. nov. from Piaui state, Brazil, are herein described and illustrated. Sphaeridiapiauiensissp. nov. resembles species of the irmleri group, like S.irmleri Bretfeld & Gauer, S.fibulifera Bretfeld & Gauer, and S.peruensis Bretfeld & Schulz, by its complex male ventral tube without asymmetrical structures or medial process. However, it differs from them by the combination of the male tibiotarsus III with a leaf-shaped IIpe chaeta and a regular IIIpi chaeta, ventral tube with 1+1 chaetae, and the absence cuticular hooks on the furca. Denisiellapiracurucaensissp. nov. resembles its congeners without the nasal organ, especially D.colombiana Ospina & Palacios-Vargas, by the presence of spiniform chaetae at least on the second antennal segment of the females, four serrated spines on tibiotarsus III, and the ventral dens chaetotaxy, but D.piracurucaensissp. nov. differs from the latter especially by the presence of 8+8 eyes and the shape of the male proximal tibiotarsal organ. To describe both species all Neotropical Sphaeridia and all described Denisiella species were surveyed, presenting notes on both genera, comparative tables, and keys for these taxa.