Review of the subgenus Geron (Geron) Meigen in the Nearctic Region (Diptera: Bombyliidae: Toxophorinae) Author Hall, Jack C. Author Evenhuis, Neal L. text Zootaxa 2003 181 1 72 journal article 10.5281/zenodo.156842 ec6153c3-7eb1-4ceb-9a60-34a24dce8a78 1175­5326 156842 Geron prosopidis Hall & Evenhuis , sp. nov. Description . Male . Head . Front with appressed silver­white scales, hair wanting; antenna black; scape and pedicel with white hair; first flagellomere narrow, tapering from base to acuminate apex; antennal ratio: 5:3:15; face cinereous pollinose, white pilose, bare medially, silver­white scales next to eye margin; oral margin white; proboscis projects beyond oral margin for a distance twice head height; gena white pilose and tomentose; occiput white pilose, lower half of occiput with scattered silver­white scales laterally, wanting on upper half; ocellar tubercle with white hair. Thorax . Mesonotum dull black, side and anterior margin lightly cinereous; median longitudinal cinereous stripe undivided, tapering posteriorly, nearly reaching scutellum; notum white pilose, tomentum wanting; pleura white pilose and tomentose; legs black, mid and hind tibiae brownish, legs with white hair and scales; halter with stem brown, knob white; scutellum white pilose, tomentum of a few white scales laterally at base. FIGURES 50–53 . Geron male genitalia. 50 , G. peucon Hall & Evenhuis , sp. nov. ; a , lateral view; b , gonocoxa, ventral view. 51 , G. prosopidis Hall & Evenhuis , sp. nov. ; a , lateral view; b , gonocoxa, ventral view. 52 , G. rufipes Macquart ; a , lateral view; b , tip of gonocoxa, dorsal view. 53 , G. senilis (Fabricius) ; a , lateral view; b , gonocoxa, dorsal view, phallic complex removed. Wing . Hyaline; venation normal; crossvein r­m at middle of cell dm; crossvein m­cu straight or nearly so; basicosta with white hair. Abdomen . Entirely white pilose and tomentose, the latter not dense; tergites with lateral margins narrowly pale; sternites with posterior margins narrowly pale. Genitalia ( Fig. 51 ) with gonocoxa in ventral view flat, without depressions or ridges; gonocoxa in lateral view broadly rectangular, lower margin with small projection on apical third; gonostylus short, broad, rounded apically; lateral ramus thick, acuminate apically, coextensive with gonostylus; dorsolateral ramus stout, rounded apically, nearly as long as lateral ramus. Female . As in male except as follows: Head . Eyes separated at vertex by slightly more than width of ocellar tubercle; front with white hair and silver­white scales; occiput with pale yellow scales on upper half. Thorax . Mesonotum with cinereous median longitudinal stripe not extending much beyond middle of notum; notum with abundant yellow tomentum; scutellum yellow tomentose; fore tarsi with palynophilic setae. Abdomen . Dorsum yellow tomentose. Genitalia with posterior projection of tergite VIII black, rounded; vaginal furca ( Fig. 20 ) simple, upper half narrowly V­shaped; lower half with arms curved outward, thin, apical half elongately swollen and slightly angled outward. Types . Holotype male and allotype (Mesquite Springs, San Bernardino County, California 14.v.1981 , J.C. Hall). Paratypes . United States . Arizona . Yavapai County: 1, Prescott, 29.vii.1932 (P.H. Timberlake); Pima County : 4, Tucson, 14.v.1961 , 26.v.1961 (R.H. & E.M. Painter); Coconino County: 11, S Rim Grand Canyon, 21–22.vii.1932 (R.H. Painter). California . San Bernardino County: 12, topotypic, 14.v.1981 , 7.vii.1982 (J.C. Hall); 11, Acton Canyon, 28.ix.1983 J.C. Hall); 1, 2.8 mi. W Hodge, 24.x.1967 (J.C. Hall); 2, Rialto, 10.viii.1955 (J.C. Hall); 1, Ontario, 19.x.1972 (N.L. Evenhuis); Inyo County : 14, 12 mi . E Keeler, 7.vii.1982 (J.C. & E.M. Hall); 45, Amaragosa Canyon, 8.vii.1983 (J.C. Hall); 2, Saline Valley, 24.iv.1975 (J.D. Pinto); 90, Wild Rose Station, 11.ix.1981 (J.C. Hall); 8, Deep Springs, 16.vii.1957 (E.I. Schlinger); Mono County: 8, Mono Lake, 16.viii.1958 (R.H. & E.M. Painter); Lassen County: 3, Doyle, 12.viii.1958 (R.H. & E.M. Painter); Fresno County: 1, Shaver Summit, 9.iv.1957 (R.H. & E.M. Painter); 1, Little Panoche Creek, 14.vii.1951 (J.C. Hall); Riverside County: 1, Mecca, 13.iv.1934 (P.H. Timberlake); 1, Thomas Mtn., 31.v.1984 (J.C. Hall); San Diego County: 1, Chihuahua Valley, 17.viii.1958 (E.I. Schlinger); Imperial County: 1, Calexico, 2.x.1947 [no collector given]. Colorado . Mesa County: 2, 21 mi . NE Gateway, 9.viii.1963 (N. & B. Marston); Huerfano County: 2, 7 mi . E. Walsenburg, 11.vii.1918 (A.L. Melander). Kansas . Greeley County: 6, 3 .x.1940 (R.H. Painter). Nevada . Nye County: 11, 15 mi . W Tonopah, 7.vii.1980 (J.C. & E.M. Hall). Utah . Beaver County: 3, 7 mi . S. Beaver, 3.ix.1979 (J.C. & E.M. Hall); same data, 21.viii.1959 (R.H. & E.M. Painter). Millard County: 1, Wahwah Mountains, 21.viii.1957 (R.H. & E.M. Painter); 1, Delta, 5.viii.1948 (G.E. Bohart). Iron County: 3, Cedar City, 22.viii.1957 (R.H. & E.M. Painter). Toole County: 9, Skull Rock Pass, 20.viii.1957 (E.M. & R.H. Painter). Washington . Yakima County: 2, Yakima, 18.vii.1920 (A.L. Melander). [Unknown County]: Knightmere, 9.viii.1919 (A.L. Melander). Wyoming . Fremont County: 17, 40 mi . SE Dubois, 5.viii.1958 (R.H. & E.M. Painter). Sweetwater County: 1, 41 mi . E. Rock Springs, 15.viii.1963 (N. Marston). Canada . British Columbia : 4, Keromeos, 19.vii.1910 [collector not given]. Mexico . Nuevo León : 1, 7 mi . W Iturbide, 26.ix.1963 (R.H. & E.M. Painter). Holotype and allotype deposited in USNM. Paratypes deposited in USNM and UCR. Variation . This is a very tiny species, usually about 4 mm in length, however, a few specimens reach 7 mm in length. The tomentum on the upper portion of the body varies from white to shiny yellow. Discussion . This species appears to be correlated with the distribution of Prosopis pubescens , it being commonly collected at the flowers, although it has been taken throughout the southwest on other plants. Geron prosopidis appears to be closely related to G. argutus . Both species are small and are similarly colored. The minor differences noted in the male (cf. Figs. 33 and 51 ) and female genitalia (cf. Figs. 4 and 20 ) should serve to distinguish the two species. Biology . Immature stages unknown. Adults have been taken at flowers of Prosopis pubescens , Heliotropium curassavicum , Crucea subulata , and Chrysothamnus sp. Distribution : Canada (British Columbia ); United States (Arizona, California, Colorado, Kansas, Nevada, Utah, Washington, Wyoming); Mexico (Nuevo León). Etymology . The specific epithet refers to the type series being collected from flowers of Prosopis .