Ormiophasia obscura ( Séguy, 1926b ),

Gudin, Filipe M. & Nihei, Silvio S., 2019, Taxonomic revision of the Neotropical genus Ormiophasia Townsend, 1919 (Diptera: Tachinidae), with the description of eight new species, Zootaxa 4643 (1), pp. 1-74: 46-48

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Ormiophasia obscura ( Séguy, 1926b )


Ormiophasia obscura ( Séguy, 1926b) 

( Figs 5HView FIGURE 5, 9HView FIGURE 9, 11HView FIGURE 11, 30View FIGURE 30)

Plagiatormia obscura Séguy, 1926b: 19  (description of male). Holotype male (MNHN), examined. Type locality: Argentina, upper Paraná River , Teyú Cuaré Park, near San Ignacio.

Plagiatormia obscura: Séguy (1927a: 424  ; catalog). Ormiophasia busckii: Townsend (1931: 82  ; synonymy of P. obscura  with O. busckii  ); Townsend (1938: 236; catalog); Sabrosky (1953:182; catalog); Tavares (1964: 38; comments on synonymy).

Ormiophasia obscura: Guimarães (1971: 22  ; catalog).

Type material examined. HOLOTYPE ♂ ( Figs 5HView FIGURE 5, 9HView FIGURE 9, 11HView FIGURE 11, 30View FIGURE 30): “Museum Paris/ Républ. Argentine / Haut Pa- rana/ Teju Cuare, pr. [near to] San Ignacio/ E.R. Wagner [leg.] 1911”/ “Type”/ “ Plagiatormia obscura Seguy  / Type/ E. Séguy det. 1925”/ “ P. obscura  , 113” ( MNHN). 

Distribution. Argentina (department of San Ignacio).

Diagnosis. Ormiophasia obscura  can be distinguished from other species of Ormiophasia  by head with silver pruinosity ( Fig. 5HView FIGURE 5); clypeus of same color as frontoclypeal membrane; wing hyaline ( Fig. 30DView FIGURE 30); and thorax and abdomen brown ( Fig. 9HView FIGURE 9, 11HView FIGURE 11). Ormiophasia obscura  can be confused with O. busckii  and O. cruzi  because of the brown color of the body and the clypeus of the same color as the frontoclypeal membrane. However, O. obscura  has ocellar triangle setulose (bare in O. busckii  ; Fig. 15View FIGURE 15 C–D) and does not have the contrast of head pruinosity ( Figs 5DView FIGURE 5, 7DView FIGURE 7) and weakly infuscated wing ( Fig. 21GView FIGURE 21) of O. cruzi  .

Redescription of male. Body length 6.98. Wing length 7.47 mm (n = 1).

Coloration. Head silver-pruinose ( Fig. 5HView FIGURE 5). Frontal vitta and ocellar triangle dark brown. Fronto-orbital plate and lunule brown. Antenna yellowish-orange to brownish-orange. Parafacial, gena, facial ridge, face and mouthparts brown. Occiput brown in upper area, becoming light brownish-yellow in lower area. Thorax silver-pruinose ( Figs 9HView FIGURE 9, 11HView FIGURE 11). Scutum brown; presutural scutum with three silver-pruinose stripes merged posteriorly after suture. Postpronotal lobe and lateral surface of thorax brown. Scutellum and subscutellum brown. Wing hyaline. Tegula, basicosta, veins, halter and calypteres brown. Legs brown. Abdomen brown at base, becoming dark brown after tergite three; with silver pruinosity.

Head ( Figs 5HView FIGURE 5, 30View FIGURE 30 A–B). Elliptic in frontal view; ratio of head height/head width 0.75. Ocelli 1.5 times the diameter of dorsal ommatidia. Postocellar setae 2. Frontal vitta entirely obliterated. Frontal setae 8, convergent, posterior ones shorter and weaker. Arista weakly plumose. First flagellomere 2.3 times longer than pedicel. Face 1.4 times wider than facial ridge. Facial ridge 2.1 times wider than parafacial.

Thorax. Basisternum 0.54 times as high as wide ( Fig. 30CView FIGURE 30); median upper margin rounded and long, subrectangular. Prosternal tympanal membrane 0.75 times as high as wide. Proepimeral setae 2, upcurved. Anterodorsal corner of anepisternum with 1 weak seta, about 1/2 length of first notopleural seta; posterior row with 7 setae. Meral setae 8. Wing. Subequal to body length, three times longer than wide. Basicosta subequal in width to tegula. Base of vein R 4+5 with 2 dorsal and 2 ventral setae. Section of vein M between crossvein dm-cu and M 1 straight. Legs. Fore femur with row of 11 dorsal setae from base to apex and row of 14 posteroventral setae from base to apex. Fore tibia with row of 3 equally-spaced anterodorsal setae and 1 preapical seta. Mid femur with 3 posteroventral basal setae.

Terminalia. Not dissected.

Female. Unknown.

Remarks. Due to the lack of examined material from Argentina it is not possible to make any advances in the taxonomy of O. obscura  . The holotype male is the only specimen available and its terminalia could not be examined. It is possible, though, to refute the synonymy of O. obscura  with O. busckii  proposed by Townsend (1931), since O. obscura  has a setulose ocellar triangle. Regarding the species of Ormiophasia  with distribution closer to O. obscura  , O. cruzi  extends to Argentina, Misiones, and could be even interpreted morphologically as the same species as O. obscura  . The contrast of pruinosity on the head is diagnostic for O. cruzi  , but it is more visible in females, which are not known for O. obscura  . Thus, the examination of male terminalia of O. obscura  would be decisive to resolve this issue, but this necessitates additional material. Furthermore, the diagnostic character assigned to O. obscura  by Séguy (1926b: 20) in his key (bend of M rounded) is not reliable, since this character shows intraspecific variation in many Ormiophasia  species.


Museum National d'Histoire Naturelle














Ormiophasia obscura ( Séguy, 1926b )

Gudin, Filipe M. & Nihei, Silvio S. 2019

Ormiophasia obscura: Guimarães (1971: 22

Guimaraes, J. H. 1971: 22

Plagiatormia obscura: Séguy (1927a: 424

Tavares, O. 1964: 38
Townsend, C. H. T. 1938: 236
Townsend, C. H. T. 1931: 82
Seguy, E. 1927: 424

Plagiatormia obscura Séguy, 1926b: 19

Seguy, E. 1926: 19