A new species of Neoalcathous Wang & Huang, 1989, N. annamica sp. nov., is described from Central Vietnam, extending the distribution of the genus to this country. A translation of the description of the genus originally in Chinese is given and the genus is transferred to the subfamily Aphaeninae. The habitus and male genitalia of the species are comprehensively illustrated and an identification key to the species of the genus is provided, as well as a distribution map. A specimen from China, Yunnan, is also recorded from photographs.