Stenopogon obscuriventris Loew, 1872

Lavigne, Robert J. & Dennis, Steve, 2019, Robber flies (Insecta: Diptera: Asilidae) of Wyoming, USA with keys to genera and species, Zootaxa 4662 (1), pp. 1-126 : 111

Stenopogon obscuriventris Loew

Stenopogon obscuriventris Loew, 1872: 69 .

Recognition characters: Brownish species; length 20–27 mm; mystax yellowish; bristles and setae of mesonotum black except those along dorsolateral margins straw white, humerus with fine straw white setae only; metapleural bristles lacking; scutellum black, golden brown pollinose, 7 yellowish marginal bristles; first posterior cell of wing open, and angle of wings milky white; abdominal tergites grayish brown pollinose; femora of legs black, apical 1/3 yellowish, tibiae yellowish with apical 3/8 of hind and tips of fore and middle black; genitalia reddish brown, hypandrium deeply emarginate with setae orange, short, and dense on apices. Easily separated from all other species by the shape of the hypandrium that is a “U” shape when viewed from below, and the presence of black macrotrichia on costal vein of wing.

Distribution: ALBANY: 26 June 1963, 4 July 1964 ( LDH); Laramie, 26 June 1963 ( RPB), 28 June 1963 ( LDH). CARBON: Bottle Creek Campground, Sierra Madre Mtns., 5 July 1963 ( RJL); 22.5 km S of McFadden, 20 July 1965 ( MHB); Rawlins, 26 June 1920 (?- AMNH). FREMONT: 48 km S of Lander, 13 July 1955; 1 km NW of Riverton, 5 June 1972 ( RJL). PLATTE: Wheatland, 8 July 1964 ( LDH). SUBLETTE: S of Pinedale, 24 July 1968 ( RJL); 16 km N of Pinedale, 29–30 July 1968 ( WAN). SWEETWATER: Rock Springs, 29 June 1920 (coll.?- AMNH); 16 km S of Shoshoni, 20 July1965 ( KJS); 11 km SW of Shoshoni, 7–14 June 1972 ( RJL, SD). TETON: Jackson, 13–17 July 1920 (?- AMNH); String Lake, Tetons, 7 July 1941 ( CPA). UINTA: Evanston, 17 June 1959 ( WDF). Recorded in Carbon Co., Centennial, Green River and Medicine Bow by Adisoemarto (1967); also, recorded in Wyoming by Lavigne (1992).

Habitat: Douglas fir forest (clearings within the forest where shrubs and grasses are dominant), sagebrush steppe shrub and grassland, and grama-buffalo grass grassland vegetation types. Areas where shrubby vegetation, such as big sagebrush ( Artemisia tridentata ), is abundant. At the Bottle Creek Campground this species was found both in open pasture and in the sun along a dirt road through the forest.

Ethology: Rests on and forages from soil and low growing vegetation.

Prey: DIPTERA , Asilidae : Dicropaltum mesae (as Asilus mesae ), 11 km SW of Shoshoni, 7 June 1972; Cyrtopogon bimacula Walker, Bottle Creek Campground , 5 July 1963; Calliphoridae : Phormia regina Meigen, Albany Co. , 26 June 1963; EPHEMEROPTERA , Caenidae : Trichorythodes minutus Traver , 11 km SW of Shoshoni, 8 June 1972; HEMIPTERA (Heteroptera) , Coreidae : Leptocoris trivittatus (Say) , 8 June 1972; Lygaeidae : Nysius sp., 11 km SW of Shoshoni, 8 June 1972; HYMENOPTERA , Apidae : Apis mellifera L., 11 km SW of Shoshoni, 5 June 1972; 7 June 1972 (two records); Formicidae : Camponotus sp. (winged reproductives, four records); Formica sp. (winged reproductives, two records); LEPIDOPTERA, Unidentified , 14 June 1972. ORTHOPTERA (see Lavigne 1992).