Micropsectra Kieffer, 1909 is described and diagnoses presented for the imaginal (♂♂), pupal and larval stages; females of the notescens-group are described. The genus contains at present 83 species of which 9 are described on females. The type material for 16 of these species has not been found. 142 species which have been listed under Micropsectra are presented in alphabethical order. This list contains: name of author, reference to description. name of original genus, present status of species, reference to the paper in which this was listed, collection in which the type material is deposited. Morphological characteristics, evolutionary trends and phylogenetic relationships of Micropsectra are discussed. The genera Rheotanytarsus, Parapsectra, Krenopsectra, Micropsectra and Paratanytarsus form a monophyletic group within the tribe Tanytarsini. The group is referred to as the Micropsectra series. Rheotanytarsus, the most plesiomorphic genus in the series, has a worldwide distribution. This supports the conclusions reached by the morphological analysis. The genera Parapsectra and Krenopsectra are only known from the Palaearctic and Nearctic Regions. The great majority of Micropsectra species are found in the Palaearctic and Nearctic Regions. A smaller number of species occur in the northern part of the Oriental Region, which has the same environmental conditions as the adjacent areas of the Palaearctic Region. Two doubtful species have been reported from India. Genus Paratanytarsus has a wider distribution but clearly has its origin on the northern hemisphere. The habitat selection in the Micropsectra series is studied and compared with the phylogeny. The species within the plesiomorphic genera Rheotanytarsus, Parapsectra and Krenopsectra are found in streams and springs. In the more apomorphic genus Micropsectra many of the species occur in these types of habitats, though there are also a comparatively high number of species occurring in lakes. Paratanytarsus, the most apomorphic genus contains species which inhabit shallow standing waters. It seems probable that the ancestor of the Micropsectra series was an inhabitant of running water. A lectotype is designated for Tanytarsus retusus Goetghebuer.