Taxonomic review of the genus Aldrichiopa Guimarães, 1971 (Diptera: Tachinidae) with notes on antennal morphology and description of a new species Author Torres-Domínguez, Diana Marcela 0009-0005-1198-5081 División Entomología, Museo Argentino de Ciencias Naturales “ Bernardino Rivadavia ” (MACN) - CONICET. Buenos Aires, Argentina dianamarcela24@gmail.com Author Gallardo, Fabiana 0000-0002-3849-4144 División Entomología, Museo de La Plata, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata. La Plata, Argentina. Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CICPBA) mulierii@yahoo.com Author Mulieri, Pablo R. 0000-0001-6762-2312 División Entomología, Museo Argentino de Ciencias Naturales “ Bernardino Rivadavia ” (MACN) - CONICET. Buenos Aires, Argentina gallardo@fcnym.unlp.edu.ar text Zootaxa 2024 2024-01-31 5405 3 354 380 http://dx.doi.org/10.11646/zootaxa.5405.3.2 journal article 10.11646/zootaxa.5405.3.2 1175-5326 10603488 CBF7C73F-E856-44D4-A034-0FC18871703D Aldrichiopa Guimarães, 1971 Aphelogaster Aldrich, 1934: 22 (junior homonym of Aphelogaster Kolbe, 1897 ). Aldrichiopa Guimarães, 1971: 165 ( nomen novum for Aphelogaster Aldrich, 1934 ). Type species: Aphelogaster coracella Aldrich, 1934: 22–23 , by original designation [ Argentina ]. References: Aldrich (1934: 2) , key to genera of Patagonian Tachinidae ; Townsend (1936: 137) , key to genera of Actiini including Aphelogaster ; Townsend (1940: 192) , redescription of Aphelogaster ; Guimarães (1971:165) in catalogue of the Diptera of the Americas South of the United States ; Guimarães (1977:19) host information; O’Hara et al. (2019: 102 , 2020: 127 ) in world checklist; O’Hara et al. (2021: 54) , in catalogue of the Tachinidae of Chile . Description. Coloration ( Figs. 1 , 5 ). Integument shiny black to brown. Frontal vitta brown to reddish brown. With a distinctive reddish-brown genal groove and genal dilatation shiny black. Facial ridge dark brown. Head with two spots of silver tomentum, one located in the upper region of the parafacial, usually rounded and very small, located near the anterior margin of the eye but may be wide and occupy almost the entire width of the parafacial; the other spot elongated, confined to the postocular lower region and the anterior region of the gena or reaching the reddish-brown genal groove and may continue as a thin line to the oral margin. Occiput with brown, black, and white setae posterior to postocular row. Postpedicel completely covered with brownish pruinosity. Arista dark brown very short-micro pubescent. Proboscis brown to light brown. Palpus dark brown to brown. Thorax evenly shiny dark brown to black. Scutellum completely shiny dark brown to black. Wing with tegula dark brown to brown, wing membrane light-brownish tinged, darker along cell r 1 and transverse veins, basicosta brown to light brown. Legs evenly shiny dark brown to black. Abdomen shiny black to brown and male with surstylus light brown to yellowish contrasting with the dark color of the other genital structures. Head ( Figs. 1C, D ; 5C, D ). Shape in lateral view almost triangular. Eye bare. Inner (reclinate) and outer (lateroclinate) vertical setae well-developed. Ocellar setae well-developed, lateroclinate. With a row of strong setae on parafacial. Gena in profile at least 0.5x the eye height. Genal groove and dilation well-developed. Vibrissa arising at the level of facial margin. Face and ventral facial margin not visible in lateral view. Occiput convex. Scape and pedicel almost the same size, pedicel with a group of strong setae in the distal region, two of these particularly long. Postpedicel 4x the length of pedicel. Arista with short micropubescense, thickened on basal 1/4; first and second aristomere almost the same length and 0.1x the length of the third aristomere. Proboscis short, almost one third of head height. Palpus nearly same length as prementum, clavate apically. Thorax ( Figs. 1B, C, F ; 5B, C, E ). Prosternum and proepisternum bare. Postpronotum with two strong setae. Two katepisternal setae. Katepimeron bare. Anepimeral seta well differentiated from the few setae present in this structure. Anatergite bare. Meron with four meral setae. Scutellum almost trapezoidal, not pointed, bearing a basal, subapical and apical setae, apical much shorter than the others and subapicals the longest. Anterior and posterior lappets of posterior spiracle sub-equal in size. Wing with costal vein with setulae until cs 4 . Vein R 1 bare and R 4+5 dorsally setulose with 3–6 setae, restricted to the basal region. CuA 1 bare. Vein M joining vein R 4+5 before wing margin and petiole as long as or up to 1.2x length of crossvein dm-cu. Crossvein dm-cu weakly oblique, straight. Bend of M with or without small stump vein. Cell r 4+5 closed before wing margin, distinctly petiolate (cs 5 absent). Section of CuA 1 between dm-cu and wing margin 0.3–0.5x the length of the preceding section. Fore coxa enlarged and long, almost half of the length of the anterior femur, and inner surface bare. Abdomen ( Figs. 1A, B ; 2A ; 5A, F ; 6A ). Long-oval. Mid-dorsal depression of syntergite 1+2 extending to or not reaching hind margin of that segment. Syntergite 1+2 without median marginal and discal setae. Tergites 3 and 4 without discal and marginal setae. Tergite 5 with a row of marginal setae. Male terminalia ( Figs. 2 , 3 , 6 ): Sternite 5 with projections on the inner margin and a membranous transverse band that can be expanded or not. Sternite 6 and segment 7+8 superimposed at right side. Epandrium broad and convex. Cerci free, not fused medially, with short setae almost throughout, finger-shaped. Surstylus well-developed; broad and robust basally in lateral view, distally straight, finger-shaped. Pregonite plate-like and entirely fused medially to each other. Postgonites well-developed. Basiphallus and epiphallus very close, appearing to constitute a single structure. Basiphallus attached to distiphallus by flexible membrane. Distiphallus short, with a sclerotized basal portion, membranous distally, without ornamentation and truncate apex. Geographic distribution ( Fig. 7 , Table 1 ). Neotropical, South America ( Argentina , Chile ). Remarks. The transverse suture is weak and poorly differentiated in this genus and the thorax chaetotaxy, is variable and difficult to observe, due to the poor differentiation and thickening of the scutal setae and the dark and shiny integument of the specimens. Aldrichiopa may be confused with species of Ateloglutus with which they are sympatric but differ by its smaller size, triangular head, scutellum without preapical setae, distinctive wing venation, and male genitalia without the elongated, and ribbon-like distiphallus. Aldrich (1934) referred to Aldrichiopa as related to Wagneria Robineau-Desvoidy (not found in the Neotropics) but differing in the absence of setae on abdominal tergites.