The genus Planinasus Cresson is revised and includes 18 extant and one fossil species. We clarify the status of the three previously described species and describe 15 new species as follows (type locality in parenthesis): Planinasus aenigmaticus (Colombia. Bogota: Bogota (04°35.8'N, 74°08.8'W)), Planinasus neotropicus (Panama. Canal Zone: Barro Colorado Island (09°09.1'N, 79°50.8'W)), Planinasus kotrbae (Ecuador. Orellana: Rio Tiputini Biodiversity Station (0°38.2'S, 76°08.9'W)), Planinasus miradorus (Brazil. Maranhão: Parque Estadual Mirador, Base da Geraldina (06°22.2'S, 44°21.8'W)), Planinasus tobagoensis (Trinidad and Tobago. Tobago. St. John: Parlatuvier (11°17.9'N, 60°39'W)), Planinasus xanthops (Ecuador. Orellana: Rio Tiputini Biodiversity Station (0°38.2'S, 76°8.9'W)), Planinasus argentifacies (Peru. Madre de Dios: Río Manu, Pakitza (11°56.6'S, 71°16.9'W; 250 m)), Planinasus insulanus (Dominican Republic. La Vega: near Jarabacoa, Salto Guasara (19°04.4'N, 70°42.1'W, 680 m)), Planinasus nigritarsus (Guyana. Conservation of Ecological Interactions and Biotic Associations (CEIBA; ca. 40 km S Georgetown; 06°29.9'N, 58°13.1'W)), Planinasus atriclypeus (Brazil. Rio de Janeiro: Rio de Janeiro, Floresta da Tijuca (22°57.6'S, 43°16.4'W)), Planinasus atrifrons (Bolivia. Santa Cruz: Ichilo, Buena Vista (4-6 km SSE; Hotel Flora y Fauna; 17°29.95'S, 63°33.15'W; 4-500 m)), P. flavicoxalis (West Indies. Dominica. St. David: 1.6 km N of junction of roads to Rosalie and Castle Bruce (15°23.8'N, 61°18.6'W)), Planinasus mcalpineorum (Mexico. Chiapas: Cacahoatan (7 km N; 15°04.1'N, 92°07.4'W)), Planinasus nigrifacies (Brazil. São Paulo: Mogi das Cruzes, Serra do Itapeti (23°31.5'S, 46°11.2'W)), Planinasus obscuripennis (Peru. Madre de Dios: Río Manu, Erika (near Salvación; 12°50.7'S, 71°23.3'W; 550 m)). In addition to external characters, we also describe and illustrate structures of the male terminalia and for Planinasus kotrbaesp. n., the internal female reproductive organs. Detailed locality data and distribution maps for all species are provided. For perspective and to facilitate genus-group and species-group recognition, the family Periscelididae and subfamily Stenomicrinae are diagnosed and for the latter, a key to included genera is provided.
Keywords: Diptera; New World; Periscelididae; Planinasus; Stenomicrinae; new species.