Nearly 400 species and subspecies of phlebotomine sand flies in the medically important genus Lutzomyia are identified by taxonomic keys to the adults and by associated illustrations. References to existing and new information on their geographic distributions (with maps), biology, and disease relationships are included.The following 9 new species in the genus are described: caminoi Young & Duncan, christenseni Young & Duncan, clitella Young & Perez, falcata Young, Morales & Ferro, gibba Young & Arias, nemorosa Young & Perez, reinerti Young & Duncan, sinuosa Young & Duncan, and torvida Young, Morales & Ferro. The previously unknown females of moucheti, omagua and pelloni are described. New junior synonyms include spinosa Floch & Abonnenc (= damascenoi Mangabeira) and tikalensis Leon (= permira Fairchild & Hertig). The status of nuneztovari anglesi Le Pont & Desjeux as a subspecies of n. nuneztovari is rejected. The subgenus Xiphomyia of Artemiev 1991 is a junior homonym of Xiphomyia of Alexander 1916. The subspecies name, cruzi of Gonzalez & Garcia-Avila 1981, is a junior homonym of cruzi of Mangabeira 1938. Lutzomyia paulwilliamsi Martins, Falcão & Silva is a junior synonym of Lutzomyia monticola (Costa Lima).