Dilophus pectoralis Wiedemann 1828
Creators: name: Pacheco Da Silva, Vitor C.
name: Schelesky-Prado, Daniel De C.
name: Fitzgerald, Scott J.
name: Serra, Wilson Sebastián
name: Scarabino, Fabrizio
name: Costa, Andrés
name: Hagopián, Damián
name: Martínez, María
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Bibionidae
Dilophus
Dilophus pectoralis

description: Dilophus pectoralis Wiedemann, 1828 (Fig. 4B, 6A, 6B, 6G)
Type-locality. Uruguay, Montevideo.
Distribution. Argentina, Brazil, Uruguay (references below and unpublished records from Brazil).
Records in Uruguay. Montevideo (Wiedemann 1828, Hardy 1967, ♀, NHMW).
Material examined. Colonia: Colonia small farm, 2♂, 1♀, 15-viii-1944, larvae in soil, hatching adults in laboratory on 07-x-1944 (FCE-Dip 1115); Carmelo, bañado, 1♀, ii-1890, M. Palmer, leg. (FCE-FA-Dip 2376); Estanzuela, 1♀, 15-xi-1947, A. Ruffinelli, leg. (FCE-FA-Dip 2377); Durazno: site 40, 33°04’49.0”S, 56°30’29.8”W, 2♂, 10-xi-2009, E. Lorier leg., sweeping (FCE-Dip 1863); Florida: Alejandro Gallinal locality, formerly Cerro Colorado, 33°52’S, 55°33’W, 1♀, 08-xii-1993, in plants, E. Morelli leg. (FCE-Dip 1116); site 25, 33°41’03.7”S, 56°14’42.8”W, 8♂, 2♀, 01-xii-2009, E. Lorier leg., sweeping (FCE-Dip 1515); Lavalleja: Salto del Penitente, 5♂, 11♀, iii-2022, G. Morera, S. Lupo leg., cow dung emergency (FCE-Dip 1516); Maldonado: La Capuera, 34°50’34.6″S, 55°07’32.5″W, 1♂, 18-xi-2023, M. Panzera leg., inside the car (FCE-Dip 1517); Ocean Park, mouth of the Potrero stream, 34°52’35.9”S, 55°06’32.6”W, 10♀, 30-xii-2012, M. Zarucki leg. (MNHN 2585);. Punta Ballena, 34°54’33.4”S 55°02’11.4”W, 2♀, 05-xi-2023, L. Rabinovich leg., pitfall in the beach (FCE-Dip 2469); Salto de Agua stream, 34º8’S, 55º1’W, 1♂, 2♀, 04-iv-1944, in the grass, bank of the stream (FCE-Dip 1117); Montevideo: 1♀, 11-xi-1888, (FCE-FA-Dip 2378); 1♀, 04-ix-1951, D. Puppo leg. (FCE-FA-Dip 2379); Buceo neighborhood, 34°54’S, 56°08’W, 5♀, 08-xi-2006, M. Martínez leg., in garden (FCE-Dip 1118); Centro neighborhood, Paysandú and Andes street, 34°54’S, 56°11’W, 1♂, 1♀, 11-xi-2011, Martínez leg., in garden (FCE-Dip 1119); Sayago, 1♂, 1♀, 05-ix-1951, P. Leuyirym, leg. (FCE-FA-Dip 2380); same data, except:, 1♀, 05-iii-1956, A.E. Llanes leg. (FCEFA-Dip 2381); Unión, 8 de Octubre and Sanguinetti Street, 34º52’S, 56º08’W, 36♀, 10-xi-2003, M. Meneguel leg., in garden (FCE-Dip 1120); Paysandú: Termas de Guaviyú, 31°50’13.6”S, 57°53’32.8”W, 1♂, 19-x-2014, W. S. Serra leg. (MNHN 1905); Rocha: Isla del Padre, 33°10’23.7”S, 53°42’19.4”W, 2♀, 25-iii-2024, M. Panzera leg. (FCE-Dip 2470); La Paloma, 1♀, 22-iv-1956, U. Ruggeri, leg. (FCE-FA-Dip 2382); Valizas (34°20’12.4”S 53°47’24.6”W), 2♀, 25-ii-2012, W. S. Serra leg. (MNHN 1656); Santa Teresa, Playa del Barco, 33°59’47.2”S, 53°32’05.9”W, 1♀, 18-27-ii-2015, W. S. Serra leg. (MNHN 2586); Santa Teresa, 33º59’53.98”S, 53º32’16.59”W, 1♂, 19-iii-2018, W. S. Serra leg. (MNHN 2587); Punta del Diablo, 34°02’43.5”S, 53°32’12.1”W, 1♀, 3-xi-2012, W. S. Serra leg. (MNHN 2344); San José: 1♀, L.C. Bollo, leg. (FCE-FA-Dip 2383); Ciudad del Plata, Delta del Tigre, 34°45’S, 56°21’W, 1♂, 15-iii-2011, M. Martínez leg., in garden (FCE-Dip 1121); Sierra de Mahoma, 34º04’S, 56º53’W, 15♂, 10-ix-1954, larvae under manure, hatching of adults in laboratory on 26-x-1954 (FCE-Dip 1122); same data, except: 14♀ (FCE-Dip 1123); same data, except: 7♂ 6♀ (FCE-Dip 1521–1533); Tacuarembó: Palo Borracho, 31°42’26.2”S, 55°59’45.7”W, 1♀, vi-1954, E. Valdés leg. (FCE-FA-Dip 2384); Treinta y Tres: Arrozal Treinta y Tres, 20♀, 16-xi-1962, P. San Martín leg., in flower (FCE-Dip 1124).
iNaturalist records. (2023). Canelones: Atlántida, 34°46’S, 55°45’W, 1♀, 11-ix-2023, S. Mallo leg., S. Mailhos det.; Ciudad de la Costa, 34°49’33.8”S, 55°57’40.5”W, 1♀, 24-x-2020, M. Silvera leg., det., L. Rubio det.; La Floresta, Rambla Dr. M. Perea, 34°45’42.6”S, 55°41’26.5”W, 1♂, 13-xi-2021, Guardianes de la Costa leg., S. Mailhos, L. Rubio det.; Las Piedras, El Colorado, 34º43’S, 56º13’W, 1♀, 26-x-2022, E. Monteghirfo leg., L. Rubio det.; Route 74, Km 32.800, 34°43’39.1”S, 56°02’13.8”W, 1♀, 02-xi-2022, F.A. Toso leg., L. Rubio det.; Santa Lucía, Picada Alaniz, 34°28’44.3”S, 56°24’06.7”W, 1♀, 31-iii-2022, G. Menéndez leg., L. Rubio det.; Colonia: Colonia del Sacramento, Continuación de la Rambla de Las Américas, 34º28’S, 57º50’W, 1♀, 24-x-2021, N. Viera leg., L. Rubio det.; Flores: near Cerro Colorado, 33°43’36.4”S, 56°48’00.0”W, 1♀, 12-xi-2022, J. Lapetina leg., S. Mailhos det.; Maldonado: Garzón, 34º35’S, 54º32’W, 1♂, 19-xi-2023, S. Mailhos leg., det.; Near Pan de Azúcar, 34º77’S, 55º27’W, 1♂ 1♀, 02-xi-2021, R. Roibal leg., L. Rubio det.; Piriápolis, 34°52’S, 55°16’W, 1♀, 01-xi-2022, S. Mallo leg., D. Schelesky-Prado, det.; Punta Negra, 34°53’S, 55°13’W, 1♀, 11-xi-2022, P. Bidondo leg., det., L. Rubio det.; Montevideo: Buceo neighborhood, 34°53’30.0”S, 56°08’04.0”W, 1♀, 21-iii-2020, A. Costa leg., det., and @ mirmeleon det. (Figs. 6A, 6B); Carrasco neighborhood, Alfonso Brocqua street, 34°52’41.7”S, 56°03’10.9”W, 1♀, 15-xi-2022, S. Mailhos leg., det., L. Rubio det.; La Figurita neighborhood, 34°52’S, 56°10’W, 1♀,. 30-x-2022, M. Urquiola leg., L. Rubio det.; Mercado Modelo neighborhood, house, 34°52’11.2”S, 56°09’28.3”W, 1♂ 1♀, 24- x-2020, P. Balduvino leg., L. Rubio det.; Río Negro: near Ruta 24 Guyunusa, 32°50’31.7”S, 57°57’16.6”W, 1♀, 21-x-2021, S. Mailhos leg., L. Rubio det.; Ruta 24 Guyunusa, near San Javier, 32°41’42.7”S, 57°59’49.7”W, 1♀, 21-x-2021, S. Mailhos leg., L. Rubio det.; Parque Nacional Esteros de Farrapos, near San Javier, 32°43’54.5”S, 58°07’46.0”W, 1♀, 14-iii-2021, A. Costa leg., L. Rubio det., in Sesbania sp. (Magnoliopsida, Fabaceae); same data, except: female being preyed upon by Cosmoclopius nigroannulatus Stål, in Pseudognaphalium gaudichaudianum (DC.) Anderb (Magnoliopsida, Asteraceae) (Fig. 6G); Rivera: near Poblado la Villa, 31°22’00.8”S, 55°05’00.2”W, 1♀. 22-x-2021, A. Machado leg., L. Rubio det.
General references. Lynch Arribálzaga, 1881; Hunter, 1900; Kertész, 1902; Brèthes, 1908; Hardy, 1953, 1959, 1966, 1967.
Comments. Lynch Arribálzaga (1881) treated Dilophus similis Rondani, 1868, from Argentina, Buenos Aires, as a junior synonym of D. pectoralis. This synonymy was accepted in Hunter (1900), and not accepted in Kertész (1902), Brèthes (1908), and Hardy (1959, 1966). Hardy (1953) says about D. similis: “it cannot definitely be placed from the original description”, however, he places the name of the species below D. pectoralis, perhaps as a possible synonym. Here D. similis is not treated as a junior synonym of D. pectoralis, since its identity is doubtful.
Hardy (1967) studied the types housed in the NHMW collection and reported three females of D. pectoralis labeled as “ type ” from Montevideo. Additionally, he reported three males from “Wiedemann collection” which contain the same data of the females, but they had been erroneously labeled as “ thoracicus ” by Wiedemann and they were not labeled as types. He also reported that “The collection also contains a series of females labeled “ Brasilia, coll., WINTHEM””. As the date that the material was collected is lacking and part of the territory of what is now Uruguay was once occupied by Portugal / Brazil, these records for the country are uncertain.
Many records of this species are reported here, including several from iNaturalist. This is only possible due to some conspicuous features of Dilophus pectoralis that separates it from similar species. The male dorsum of thorax is mainly reddish orange except for the dark brown anterior area, while in D. golbachi (Hardy) the dorsum is black with a reddish yellow spot on each side, and in D. serenus (Hardy) the dorsum is all black (Hardy 1953). The male wing membrane of D. pectoralis is slightly fumose, almost hyaline posteriorly and brownish along the costal margin, while D. golbachi has wings brownish fumose basally (and sub-hyaline apically), and D. serenus has hyaline wings (Hardy 1953). The female pleura is reddish, while it is blackish in D. serenus, and the female of D. golbachi is unknown (Hardy 1953). The female wing membrane of D. pectoralis is dark brown, while it is just faintly fumose in D. serenus (Hardy 1953). The female tibiae of D. pectoralis are black, while in D. serenus the tibiae are yellowish (Hardy 1953).
Dilophus pectoralis was observed here as prey for Cosmoclopius nigroannulatus Stål (Hemiptera: Reduviidae) (Fig. 6G).
description: Published as part of Pacheco Da Silva, Vitor C., Schelesky-Prado, Daniel De C., Fitzgerald, Scott J., Serra, Wilson Sebastián, Scarabino, Fabrizio, Costa, Andrés, Hagopián, Damián & Martínez, María, 2025, Bibionidae (Diptera: Bibionomorpha) from Uruguay: updated inventory including first reports of four species, pp. 129-146 in Zootaxa 5588 (1) on pages 135-137, DOI: 10.11646/zootaxa.5588.1.5, http://zenodo.org/record/14896150