Rheocricotopus (Psilocricotopus) sirventorum sp. n. is described and figured based on a male from Mato Grosso, Brazil. It is tentatively placed in subgenus Psilocricotopus Sæ,ther as it has a triangular, subapical crista dorsalis and a rounded superior volsella. However, the new species apparently lacks acrostichals and has 40 dorsocentrals in 1-4 irregular rows.
Chironomidae; Orthocladiinae; Rheocricotopus; Psilocricotopus; new species; Mato Grosso; Brazil; Neotropical region
