Cryptovelia terrestris n. gen., n. sp. (Brazil), Darwinivelia fosteri n. gen., n. sp. (Galapagos Is.), Mniovelia kuscheli n. gen., n. sp. (New Zealand), and Cavaticovelia n. gen. (type-species: Speovelia aaa Gagné & Howarth, 1975; Hawaii) are described. The phylogenetic relationships between the mesoveliid genera are discussed in the light of characters revealed by the new taxa. Habitat preferences of mesoveliids include humid terrestrial and/or marginal aquatic habitats, which probably are the most ancestral, and lava-tubes, coastal caves, intertidal marine habitats, and the plant-covered freshwater surface, which probably are the derived kinds of habitats. A classification of the Mesoveliidae with a check list of genera and species is presented. Two subfamilies are recognized: Madeoveliinae (with two genera) and Mesoveliinae (seven genera). The biogeography of the Mesoveliidae is finally discussed.