Four new species of Mesorhaga Schiner (Diptera: Dolichopodidae) from Northeastern Brazil, with an identification key to South American species of the genus Author Santos, Ednaldo Bezerra Dos Universidade Estadual do Maranhão, Laboratório de Estudos dos Invertebrados, Programa de Pós-graduação em Biodiversidade, Ambiente e Saúde, 65604 - 380, Caxias, Maranhão, Brazil Author Capellari, Renato Soares Instituto Federal de Educação, Ciência e Tecnologia de São Paulo (IFSP), Campus Avaré, São Paulo, Brazil Author Limeira-De-Oliveira, Francisco Universidade Estadual do Maranhão, Laboratório de Estudos dos Invertebrados, 65604 - 380, Caxias, Maranhão, Brazil text Zootaxa 2024 2024-10-08 5519 2 243 256 http://dx.doi.org/10.11646/zootaxa.5519.2.4 journal article 10.11646/zootaxa.5519.2.4 1175-5326 13915824 96CED727-1208-41A9-8CC2-B46AFC1E2F45 Mesorhaga Schiner urn:lsid:zoobank.org:act: 2D4EF16C-BFCA-4126-A535-305FE0B46543 Mesorhaga Schiner, 1868: 217 . Type species: Mesorhaga tristis Schiner , monotypy. Aptorthus Aldrich, 1893: 48 . Type species: Aptorthus albiciliatus Aldrich, 1893 (subsequent designation by Coquillett, 1910: 509 ). Synonymized by Aldrich (1900) : 531 . Identification key to males of South American Mesorhaga For notes on other Neotropical species and a key for Mesoamerican and Caribbean species, see Bickel (2007) . 1 Femora mostly or entirely black.......................................................................... 2 - Femora yellow....................................................................................... 5 2 Wing vein M 1 with gentle curve ( Naglis 2000 , fig. 1b); fore and mid tibiae with rows of conspicuous setae ( Naglis 2000 , fig. 1a); cercus with three digitiform projections at apex ( Naglis 2000 , figs 1c–d) ( Brazil : Amazonas)......... M. saetosa Naglis - Wing vein M 1 distinctly curved, almost right angle bend (see Fig. 12 ); fore and mid tibiae without conspicuous rows of setae; cercus without remarkable projections ( Fig. 16 ) or with apical notch ( Bickel 2007 , fig. 1f)........................... 3 3 Ventral occiput with long black setae; wing membrane hyaline; halter black; all legs entirely black ( Venezuela ).................................................................................................. M. tristis Schiner - Ventral occiput with short whitish setae, wing membrane with dark brown cloud along anterior margin; halter black or yellow; apex of fore and mid femora, all tibiae and base of tarsi yellow................................................. 4 4 Cercus with some long, lateral setae near medial bend of appendage, apex with notch ( Bickel 2007 , fig. 1f) ( Peru , Ecuador and Venezuela )............................................................................ M. funebris Parent - Cercus without long, lateral setae at middle of appendage, apex homboid ( Figs 15 and 16 ) ( Brazil : Piauí )..................................................................................................... M. gomesi sp. nov. 5 Wing membrane with grayish cloud on apical fourth, between end of R 2+3 and M 1 , wing vein M 1 distinct curved, almost right angle bend ( Becker 1922 , fig. 146) ( Paraguay ).................................................. M. laeta Becker - Wing membrane hyaline, wing vein M 1 both distinctly (right angle) or gently curved................................ 6 6 Thorax with 2 pairs of acrostichal setae; surstylus much shorter than epandrial lobe ( Naglis 2000 , fig. 2b–c) ( Brazil : Amazonas)............................................................................. M. aurata Naglis - Thorax with 3 pairs of acrostichal setae; surstylus as long as epandrial lobe ( Figs 7, 8 , 23, 24 , 31, 32 )................... 7 7 Wing vein M 1 distinct curved, almost right angle bend ( Fig. 4 ); apex of cercus not noticeably enlarged and covered by setae similar in length ( Figs 22–24 ) ( Brazil : Piauí )................................................ M. parnasete sp. nov. - Wing vein M 1 gently bent towards apex ( Figs 20 , 28 ); apex of cercus noticeably enlarged, with 2–3 larger setae at apex ( Figs 23, 24 , 31, 32 )........................................................................................ 8 8 Fore tarsomere 5 slightly expanded; apex of cercus with small subrectangular expansion ( Brazil : Piauí ).................................................................................................... M. danbickeli sp. nov. - Fore tarsomere 5 as broad as preceding segments; apex of cercus triangular ( Brazil : Piauí )............. M. laetitia sp. nov.