Geron eriogonae 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 : 28-32

Geron eriogonae Hall & Evenhuis , sp. nov.

Description. Male. Head. Front silvery white tomentose, a few white hairs present; antenna black; scape with short white hair; pedicel with shorter black hair; first flagellomere narrow, evenly tapering from base to acuminate apex; antennal ratio: 7:3:25; face cinereous pollinose, white pilose, bare medially; silver­white tomentum lateral to antennal base; oral margin white; proboscis projects beyond oral margin for a distance slightly less than twice head height; gena white pilose and tomentose; occiput white pilose, lower half with white tomentum, upper half with tomentum wanting; ocellar tubercle with brownish hair.

Thorax. Mesonotum dull black, lateral margin lightly cinereous pollinose; median longitudinal stripe short, not reaching transverse suture, medially divided; notum white pilose, medially behind transverse suture, with shorter black hair; tomentum wanting; pleura white pilose and tomentose; legs black with white hair and scales; halter with stem testaceous, knob pale yellowish; scutellum white pilose, tomentum wanting.

Wing. Hyaline; venation normal; crossvein r­m at middle of cell dm; vein m­cu slightly sinuous; basicosta with white hair.

Abdomen. White pilose, dorsum with sparse white tomentum, denser on side; tergites with lateral margins narrowly pale; sternites with posterior margins narrowly pale.

Genitalia ( Fig. 38 ) with gonocoxa in ventral view flat, without depressions or ridges; in lateral view rectangular, lower margin nearly straight and with a very small, pointed projection; gonostylus short, broad, narrowed apically; lateral ramus narrow, slightly curved, nearly coextensive with gonostylus; dorsolateral ramus narrowed apically, coextensive with lateral ramus.

Female. As in male except as follows: Head. Eyes at vertex separated by about one and one­half times width of ocellar tubercle; front with yellow hair, medially with golden yellow tomentum, white tomentum laterally and above antenna; occiput with yellow hair and golden yellow tomentum on upper half. Thorax. Mesonotum and abdominal dorsum with yellow pile and yellow tomentum; legs black, mid and hind tibiae ferruginous. Genitalia with projection on tergite VIII black; vaginal furca ( Fig. 9 ) simple, upper half narrowly V­shaped, lower half with arms narrow, slightly bowed and ending apically in a small knob, which may or may not have a small, pointed, inward projection.

Types. Holotype male and allotype (Mill Creek Canyon, San Bernardino County, California, 10.viii.1947, P.H. Timberlake, on Eriogonum subscaposus . Paratypes. California. San Bernardino County: 21, topotypic, 30.vi.1936 to 24.viii.1955 (P.H. Timberlake); 6, Big Pine Camp, 2.viii.1944, 18.viii.1958 (P.H. Timberlake, R.H. & E.M. Painter); 2, Valley of the Falls, 11.viii.1935 (P.H. Timberlake); 4, Mt. Home Canyon, 24.viii.1944 (P.H. Timberlake); 12, Morongo Valley, 22.ix.1944, 4.x.1949 (P.H. Timberlake, A.L. Melander); 6, Yucca Valley, 20.viii.1936, 30.ix.1944, 5.ix.1946 (P.H. Timberlake, A.L. Melander); 5, Colton, 26.ix.1968 (P.H. Timberlake, J.C. Hall); 12, Cajon, 24.vii.1930, 28.vi.1945, 18.ix.1945 (R.H. Painter & T.F. Winburn, A.D. Melander) 18, Victorville, 30.v.1944 (A.L. Melander); 5, Arrowhead Lake, 26.viii.1956 (E.I. Schlinger), Riverside County: 22, Riverside, various dates from June through September (P.H. Timberlake, J.C. Hall, M.E. Irwin); 1, 6 mi. M Palm Springs, 6.viii. 946 (P.H. Timberlake); 1, 10 mi. W Indio, 23.viii.1957 (P.H. Timberlake); 3, Poppet Flat, 31.v.1984 (J.C. Hall); 4, Ribbonwood, 27.vii.1950 (P.H.

Timberlake); 1, 29 Palms, 9.viii.1946 (P.H. Timberlake); 1, 1.5 mi. NW Perris, 13.vi.1938 (P.H. Timberlake); 2, Bautista Canyon 27.ix.1982 (E.M. Fisher); 9, Menifee Valley, 15– 30.vi.1980 (J.D. Pinto). Inyo County : 3, 5 mi. NW Panamint Spgs., 5.vii.1953 (E.I. Schlinger); 3, Little Lake, 15.vi.1972 (J.D. Pinto). Shasta County: 4, Cassel, 15.vii.1955 (E.I. Schlinger), Butte County: 3, Feather Falls, 17.viii.1957 (T.R. Haig). Shasta County: 1, Hat Creek P.O., vii.1955 (R.D. Brown). El Dorado County: 2, Kyburz, 10.vii.1955 (H.R. Moffitt). Imperial County: 2, Calexico, 23.ix.1957 (E.I. Schlinger). San Diego County: 2, 1 mi. N Pine Hills, 28.vii.1982 (R.D. Brown). El Dorado County: 2, Kyburz, 10.vii.1955 (H.R. Moffitt). Imperial County: 2, Calexico, 23.ix.1957 (E.I. Schlinger). San Diego County: 2, 1 mi. N Pine Hills, 28.vii.1982 (J.C. Hall). Arizona. Cochise 1, 5 mi. W Portal, 1.vi.1965 (M.E. Irwin); 4, Cochise County, 16.v.1961 (R.H. & E.M. Painter). Yuma County: 15, 24 mi. N Yuma, 12.iv.1961 [collector unknown]. Pinal County: 1, Tonto Natl. Mon., 26.vii.1932 (R.H. Painter). Colorado. Montrose County: 4, N edge of Black Canyon, Gunnison Natl Mon., 5.vii.1959; 10, 12 mi. SW Crawford, 5.vii.1959 (R.H. & E.M. Painter. Montezuma County: 1, 24 mi. S Cortez, 26.viii.1965 (R.H. Painter). Prower County: 1, 2 mi. SW Hartman, 7.viii.1963 (N. Marston). La Plata County: 13, 13 mi. E Durango, 10.vii.1959 (R.H. & E.M. Painter). Montrose County: 10, 12 mi. SW Crawford 5.viii.1959 (R.H. & E.M. Painter). Routte County: 60, 22 mi. W Steamboat Springs, 15.viii.1963 (N. & B. Marston). Rio Blanco county: 10, 7 mi. S Rangley, 18.viii.1963 (N. & B. Marston). Mesa County: 4, 39 mi. NE Gateway, 19.viii.1963 (N. & B. Marston). Eagle County: 1, 17.viii.1959 (N. Marston). Utah. San Juan County: 8, 22 mi. N Monticello, 30.viii.1965 (R.H. & E.M. Painter). Cache County: 2, Logan, Aug. (F. Marlatt). Daggett County: 16, 4 mi. 5 Manila, 16.viii.1963 (N. & B. Marston); 2, 45 mi. NE Vernal, 18.viii.1963 (N. & B. Marston). 2, Lenwood, 17.vii.1957 (E.M. & R.H. Painter); 13, La Sal Mts., 7.vii.1959 (R.H. & E.M. Painter). Nevada. Humboldt County: 1, Paradise Valley, 11.viii.1958 (R.H. & E.M. Painter). Nye County: 2, Mercury, 9.vii.1961. Washington. Yakima County: 3, Buena, 24.vi.1923 (V. Argo). Adams County: 1, Lind, 28.vii.1919 (F.W. Carlson); 5, Ritzville, 29.vii.1922 (M.C. McLane). Okanogan County: 3, Pateros, 3.viii.1919 (A.L. Melander). New Mexico. Otero County: 8, White Sands, 8.viii.1931 (R.H. Painter). Wyoming. Sweetwater County: 4, 26 mi. S Greenriver, 16.viii.1963 (N. & B. Marston); 11, 70 mi. E Rock Springs. 15.viii.1963 (N. & B. Marston). 16.viii.1963 (N. & B. Marston). Carbon County: 8, 8 mi. N Baggs. MEXICO. Sonora: 2, 3 mi. N Alamos, 24.iv.1961 (R.H. & E.M. Painter). San Luis Potosí: 38, 40 mi. N San Luis Potosí, 8.viii.1963 (R.H. & E.M. Painter). Zacatecas: 1, 45 mi. SE Fresnillo, 3.ix.1962 (R.H. & E.M. Painter). Holotype and allotype deposited in USNM. Paratypes in USNM and UCR.

Variation. The pile in both sexes varies from white to pale yellow. The tomentum on the female varies from yellow to golden. The mid and hind tibiae in both sexes may be entirely black or ferruginous. In the female the vaginal furca, in the smaller specimens, usually does not have the small, pointed, inward projection developed.

Discussion. This species is much like G. nigripes Painter except the genitalia are quite different. In the main, this is a tiny species measuring 2–3 mm in length, although a few specimens reach 6 mm in length. There is also some resemblance to the Caribbean G. exumas Scarbrough & Davidson , but the female vaginal furca is different and the gonocoxa in the male is flat without projections.

Biology. Immature stages unknown. Adults have been taken at flowers of Eriogonum subscaposum , E. elongatum , E. fasciculatum, Rhamnus californica, Solidago californica, Adenostoma sparsifolium and Lesingia sp.

Distribution. United States (Arizona, California, Colorado, Nevada, New Mexico, Utah, Washington, Wyoming); Mexico (San Luis Potosí, Sonora, Zacatecas).

Etymology. The specific epithet derives from the ubiquitous southwestern desert plant, Eriogonum , the flowers on which the type species was found.

Figures

FIGURES 38 – 41. Geron male genitalia. 38, G. eriogonae Hall & Evenhuis, sp. nov.; a, lateral view; b, tip of gonocoxa, ventral view. 39, G. halli Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, ventral view. 40, G. holosericeus Walker; a, lateral view; b, tip of gonocoxa, ventral view. 41, G. infrequens Hall & Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, dorsal view, epiphallus and phallic complex removed.

FIGURES 7 – 12. Geron vaginal furcae. 7, G. cressoni Hall & Evenhuis, sp. nov. 8, G. elachys Hall & Evenhuis, sp. nov. 9, G. eriogonae Hall & Evenhuis, sp. nov. 10, G. halli Evenhuis, sp. nov. 11, G. holosericeus Walker. 12, G. infrequens Hall & Evenhuis, sp. nov.