Nine new species of Nilothauma Kieffer, N. hamadae sp. nov., N. jupau sp. nov., N. karitiana sp. nov., N. leccii sp. nov., N. marianoi sp. nov., N. mateusi sp. nov., N. txukuyana sp. nov., N. werekena sp. nov. and N. yekwana sp. nov. are described and figured, based on adult males collected in Brazil and N. maya sp. nov. on an adult male from Mexico; N. terena sp. nov. is described as male, pupa and larva based on a reared specimen from Brazil. Nilothauma aleta Roback, 1960 and N. duena Roback, 1960 are re-described and recorded from Brazil. Nilothauma longissimum Mendes & Andersen, 2009 is transferred to Beardius Reiss & Sublette, 1985 and the diagnosis of Nilothauma is emended. New records of thirteen Neotropical Nilothauma species are given and a key to the males of all known species of Nilothauma is provided.