Geron prosopidis Hall & Evenhuis

Hall, Jack C. & Evenhuis, Neal L., 2003, Review of the subgenus Geron (Geron) Meigen in the Nearctic Region (Diptera: Bombyliidae: Toxophorinae), Zootaxa 181, pp. 1-72 : 50-53

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.

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 .

Figures

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.

FIGURES 19 – 24. Geron vaginal furcae. 19, G. peucon Hall & Evenhuis, sp. nov. 20, G. prosopidis Hall & Evenhuis, sp. nov. 21, G. rufipes Macquart. 22, G. senilis (Fabricius. 23, G. stenos Hall & Evenhuis, sp. nov. 24, G. subauratus Loew.

FIGURES 30 ­ 33. Geron male genitalia. 30, G. albipennis Painter; a, lateral view; b, tip of gonocoxa, ventral view. 31, G. albipilosus Hall & Evenhuis, sp. nov.; a, lateral view; b, ventral view. 32, G. arenicola Painter; a, lateral view; b, tip of gonocoxa, ventral view. 33, G. argutus Painter; a, lateral view; b, ventral view.

FIGURES 1 – 6. Geron vaginal furcae. 1, G. albidipennis Loew. 2, G. albipilosus Hall & Evenhuis, sp. nov. 3, G. arenicola Painter. 4, G. argutus Painter. 5, G. borealis Hall & Evenhuis, sp. nov. 6, G. confusus Hall & Evenhuis, sp. nov.