ABSTRACT Taxonomic revisionary notes and identification keys are presented for two species-groups of wasps of the genus Mischocyttarus, subgenus Phi. Material of the M. wagneri and M. barbatus groups, including types, was examined in several collections, resulting in description of one new species for the first mentioned group (M. camanducaia sp. nov.), and several new synonymies for both groups as follows (senior synonym in bold): [Mischocyttarus mourei Zikán 1949 = Mischocyttarus laneiZikán 1949 = Mischocyttarus plaumanniZikán 1949]; [Mischocyttarus declaratusZikán 1935 = Mischocyttarus confirmatusZikán 1935 = Mischocyttarus brackmanniZikán 1949 = Mischocyttarus alternatusZikán 1949 = Mischocyttarus cabaunaZikán 1949]; [Mischocyttarus barbatus Richards 1945 = Mischocyttarus ecuadorensisZikán 1949 = Mischocyttarus pedunculariusZikán 1949]. In addition, several cases are demonstrated of changing in group content, with species being moved into and out of groups as required. Both groups are distributed on the highlands of Central and South America, with the M. wagneri group being endemic to southeastern areas of the continent.