The non-Palaearctic species of the genus Phthitia Enderlein are revised, including descriptions of 30 species, of which 19 are described as new by the first author: P. antillensis, P. bicalyx, P. cercipilus, P. mulroneyi, P. digiseta, P. digistylus, P. lineasterna, P. lobocercus, P. luteocercus, P. luteofrons, P. megocula, P. merida, P. nigrifacies, P. notthomasi, P. obunca, P. occimosa, P. ovicercus, P. quadricercus, and P. spinicalyx. The genera Kimosina Roháček and Aubertinia Richards are newly placed in synonymy with Phthitia, and the following new combinations are given for species previously in Kimosina: Phthitia chilenica (Duda), P. antipoda (Roháček), P. rennelli (Harrison), P. thomasi (Harrison), P. empirica (Hutton), P. levigena (Spuler), P. plumosula (Rondani), P. spinosa (Collin), P. pappi (Roháček), P. glabrescens (Villeneuve), P. ciliata (Duda), P. longisetosa (Dahl), P. sicana (Munari), P. soikai (Munari), and Archicollinella dolichoptera (Richards). Phthitia sanctaehelenae (Richards) is given as a new combination for Aubertinia sanctaehelenae Richards. Limosina phycophila Richards is a new junior synonym of Archicollinella caerulea (Duda). A key, illustrations, descriptions of adults, distribution maps, and a phylogeny are provided for all New World and Pacific species. The puparium of P. empirica is described. A lectotype is designated for P. chilenica.