Geron subauratus Loew

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 : 60-63

Geron subauratus Loew

Geron subauratus Loew, 1863: 304 (1864: 188) . Smith 1890: 378. Coquillett 1894: 111. Snow 1904: 342. Kertész 1909: 99. Johnson 1910: 747. Graenicher 1910: 36. Graenicher 1913: 180. Cole et al. 1924: 191. Painter 1932: 148. Brimley 1938: 342. Painter & Painter 1965: 423. Hull 1973: 206. Evenhuis 1982: 18. Cooper & Cumming 1993: 10. Poole & Gentili 1996: 71. Evenhuis & Greathead, 1999: 48. Skevington et al. 2001: 105.

Geron digitaria Cresson, 1919: 184 . Cole 1923: 312. Painter 1932: 153. Hull 1973: 667. Tabet & Hall 1984: 32.

Geron digitarius Cresson. Painter & Painter 1965: 423 (emendation). Hull 1973: 206. Frommer 1981: 35. Evenhuis 1983: 470. Tabet & Hall 1987: 67. Poole & Gentili 1996: 71.

Geron alba Cole, 1923: 313 . Hull 1973: 660.

Geron albus Cole. Painter, Painter & Hall 1978: 17 (emendation). Hull 1973: 206. Arnaud 1979: 211.

Male. Head. Front silvery tomentose, pile wanting; antenna black; scape and pedicel with black hair; first flagellomere linear, evenly tapering from base to acuminate apex; antennal ratio: 8:3:20; face black, white pilose, bare medially; silver tomentum laterally above; oral margin pale; proboscis projects beyond oral margin for a distance about one and one­half times head height; gena white pilose and tomentose; occiput white pilose on lower half, upper half pale yellow pilose, tomentum on lower half white, scattered, wanting on upper half; ocellar tubercle with dark brown to black hair.

Thorax. Mesonotum dull black, lateral and anterior margins cinereous; median longitudinal stripe brownish, vague, medially divided, not reaching transverse suture; notum white to pale yellow pilose, shorter black hair medially posterior to transverse suture; tomentum golden yellow, scattered; pleura white pilose and tomentose; legs black, mid and hind tibiae brownish; legs with white hair and scales; halter with stem and knob pale yellow; scutellum pale yellow pilose, tomentum golden yellow, restricted to base and lateral margin.

Wing. Hyaline to lightly infumate; venation normal; crossvein r­m at middle of cell dm; crossvein m­cu sinuate; basicosta with yellow hair.

Abdomen. Dorsum pale yellow pilose, tomentum golden yellow, scattered; side and venter white pilose and tomentose; tergites with lateral margins black; sternites with posterior margins black.

Genitalia ( Fig. 55 ) with gonocoxa in ventral view with two depressions and no central ridge; gonocoxa, in lateral view, short, rectangular, lower margin undulate, without projections; gonostylus narrow, slightly expanded apically, apex rounded, in ventral view with inward projecting lobe; lateral ramus thin, straight, nearly coextensive with gonostylus; dorsolateral ramus short, thick, more as an elongated fold in the dorsal margin of the gonocoxa.

Female. As in male except as follows: Head. Eyes at vertex separated by about twice the width of ocellar tubercle; front with white hair and golden yellow tomentum, silverwhite tomentum next to eye margin; scape with some white hair at base; ocellar tubercle with yellow to dark brown hair; occiput with yellow scales on upper half. Thorax. Mesonotum entirely golden yellow tomentose; femora with scales pale yellow, not white. Abdomen. Dorsum yellow pilose and golden yellow tomentose. Genitalia with lobe on tergite VIII broad, black; vaginal furca ( Fig. 24 ) simple; upper half V­shaped; lower half with arms diverging, not curved, apical inner margin of arm with a narrow, median, inward projection, apex of arm rounded.

Types. Lectotype of G. subauratus (Pennsylvania) deposited in MCZ (No. 12714). There are four specimens in the syntype series (2 males, 1 female from MCZ; 1 from CNC). The male in MCZ with the genitalia dissected is herein designated as the lectotype in order to stabilize the taxonomy. The lectotype has the left third antennal segment and the hind legs missing. Holotype male of G. digitaria (Highrolls, New Mexico, 11.vi.1902, [Viereck]) in ANSP (No. 6263) the number in the original description (“6207”) is incorrect. The type is in good condition, it is slightly abraded, and the right middle leg is missing. Holotype male of G. alba ( Mexico, Coronados Island, Gulf of California, 18.v.1921, E.P. Van Duzee) in CAS (No. 1236). The genitalia have been dissected and placed in a microvial on the same pin as the type. All types studied by senior author.

Material Examined. United States. Arizona. Cochise County: 1, Hose Canyon, Chiracahua Mountains, 11.vii.1967 (E.I. Schlinger); 2, Texas Canyon, Dragoon Mountains, 11.viii.1960, 29.v.1965 (M.E. Irwin); 3, Herb Matyr Dam, 14.viii.1969 (F.G. Andrews); 2, Paradise, 15.viii.1965 (C.A. Saario); 18, Portal, 2.viii.1965, 14.viii.1957, 21.viii.1967, 2.viii.1958, 3.viii.1965, 29.viii.1967 (E.I. Schlinger, S. & S. Frommer, G.W. Forrester); 2, 24 mi. W. Douglas, 18.viii.1967 (E.I. Schlinger). Santa Cruz County: 7, Madera Canyon, 16.viii.1964 (E.I. Schlinger). Mojave County: 31, Hualapai Mountains, 30.vii.1965 (M.E. Irwin). Pima County : 1, Organ Pipe Cactus National Monument, 14.iv.1961 (R.H. Painter); 1, Santa Catalina Mountains , 28.vii.1932 (R.H. Painter). California. Riverside County: Joshua Tree National Monument, Hidden Valley, 20.v.1946 (A.L. Melander). Colorado. La Plata County: 1, 2 mi. E. Durango, 10.vii.1959 (R.H. & E.M. Painter). Rio Blanco County: 1, 9 mi. S. Meeker, 2.vii.1959 (R.H. & E.M. Painter). District of Columbia. Washington, 30.vi.1920 (J.M. Aldrich). Maryland. Prince George’s County: 3, Beltsville, 9.viii.1916 (F.R. Cole). [county unknown]: Linneville, 7.viii.1913 (J.M. Aldrich). Michigan. Antrim County: 1, Bellaire, 10.vii.1941 (C.W. Sabrosky). Montmorency County: 1, Lewiston, 19.vii.1942 (C.W. Sabrosky). Van Buren County: 1, South Haven, 5.vii.1938 (C.W. Sabrosky). New Jersey. Burlington County: 1, Riverton, 12.vii.1916 (C.W. Johnson). Cape May County: 1, Avalon, 30.vii (C.W. Johnson). New Mexico. Doña Ana County: 1, 17 mi. E. Las Cruces, 10.8 ix.1962 (R.H. & E.M. Painter). Torrance County: 1, Lucy, 17.vii.1932 (R.H. Painter). San Juan County: 1, 20 mi. W. Farmington, 20.viii.1963 (N. & B. Marston). Routt County: 1, 22 mi. W. Steamboat Springs, 15.viii.1965 (N. & B. Marston). New York. Suffolk County: 1, Islip, Long Island, 7.iv.1933 (F.S. Blainton). Texas. Brewster County: 1, Alpine, 7.vii.1930 (H.M. Smith); 1, Big Bend National Park, 19.vi.1958 (R.H. & E.M. Painter). Utah. San Juan County: 1, 11 mi. SW. Monticello, 28.viii.1965 (R.H. & E.M. Painter). Washington County: 1, Zion National Park, 22.viii.1957 (R.H. Painter). Virginia. Page County: 1, Shenandoah, Big Meadows, 2.vii.1939 (A.L. Melander). Fairfax County: 1, Falls Church, 2.vii.1913, on Castanea dentata (A.L. Melander) .

Variation. Specimens identified as this species from the southwest are lighter colored than their counterparts in the east. The hair on the scape varies from white to black. The hair on the ocellar tubercle in the female is most often dark, however, there are specimens in which this hair is pale yellow. The tomentum on the body varies from golden yellow to yellow. The western specimens more often have the mid and hind tibiae ferruginous and the wings are apt to be hyaline rather than infumate.

Discussion. Both the male and female genitalia are distinctive and as such leave little doubt as to the conspecificity of the eastern and southwestern forms. Cresson (1919) was apparently correct in his assumption that his specimens of G. digitarius could belong to G. subauratus . Geron subauratus appears to be closest to G. johnsoni , but can be separated from that species by the black hairs on the scape (white in G. johnsoni ) and the placement of crossvein r­m at the middle of cell dm (beyond the middle of cell dm in G. johnsoni ).

Biology. Immature stages unknown. Adults have been taken at flowers of Baileya pleniradiata , Castanea dentata , Gutierrezia lucida, Lotus sp., and an undetermined cruciferous species.

Distribution. Canada (Ontario); United States (Arizona, California, Colorado, District of Columbia, Maryland, Massachusetts, Michigan, New Jersey, New Mexico, New York, North Carolina, Ohio, Pennsylvania, Texas, Utah, Virginia, Wisconsin). Mexico (Baja California Norte).

Figures

FIGURES 54 – 57. Geron male genitalia. 53, G. stenos Hall & Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, ventral view. 55, G. subauratus Loew; a, lateral view; b, gonocoxa, ventral view. 56, G. vitripennis Loew; a, lateral view; b, tip of gonocoxa, ventral view. 57, G. weemsi Hall & Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, ventral view.

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.