Geron argutus Painter

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 : 20-22

Geron argutus Painter

Geron argutus Painter, 1932: 145 , 158. Allred, Johnson & Beck 1965: 9. Painter & Painter 1965: 423. Hull 1973: 206. Poole & Gentili 1996: 70. Evenhuis & Greathead 1999: 38. Geron perplexus Tabet, 1979: 182 . Nomen nudum.

Geron perplexus Tabet, 2001: 49 . Syn. nov.

Description. Male. Head. Front with silver­white tomentum, hair wanting; antenna black; basal two segments with white hair; first flagellomere linear, tapering from base to acuminate apex; antennal ratio: 8:3:16; face cinereous pollinose with white hair, bare medially, tomentum silver­white laterally next to eye margin; oral margin pale; proboscis projects beyond oral margin for a distance about twice head height; gena white pilose and tomentose; occiput white pilose, tomentum white, confined to lower half; ocellar tubercle with mixed white and brownish hair.

Thorax. Mesonotum black with lateral and anterior margins cinereous pollinose; median longitudinal stripe faint, not reaching transverse suture; notum white pilose, shorter black hair medially on posterior half; tomentum wanting; pleura white pilose and tomentose; legs white pilose and tomentose, black, mid and hind tibiae and basitarsi brownish; halter with stem and knob white; scutellum with white hair, tomentum wanting.

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

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

Genitalia ( Fig. 33 ) with gonocoxa in ventral view flat, without depressions or ridges, in lateral view, rectangular, lower margin, apically with a small rounded protuberance; gonostylus narrow, rounded apically; later ramus narrow, curved apically, coextensive with gonostylus; dorsolateral ramus long, about half length of lateral ramus; aedeagus not evident.

Female. As in male except as follows: Head. Eyes at vertex separated by about one and one­half times width of ocellar tubercle; front with white hair and tomentum; occiput with pale yellow tomentum on upper half; ocellar tubercle with brown to black hair. Thorax. Mesonotum with median longitudinal cinereous stripe narrow, reaching beyond transverse suture; notum with pale yellow pile and abundant yellow tomentum; legs black, mid and hind tibiae and basitarsi ferruginous; scutellum with yellow tomentum; fore tarsi with palynophilic setae. Abdomen. Dorsum pale yellow pilose and tomentose, the latter abundant. Genitalia with posterior lobe of tergite VIII ferruginous; vaginal furca ( Fig. 4 ) simple, upper half narrowly U­shaped; lower half with arms slightly curved, narrow, swollen on inner margin at apex, then flared outward at nearly a right angle.

Types. Holotype male and allotype of G. argutus (Medora, Kansas, sand dunes, 3.vii, R.H. Painter) in USNM (No. 44871). In the holotype, the right first flagellomere is missing; otherwise the type and allotype are in good condition. The male genitalia have been dissected and placed in a microvial attached to the pin. Both holotype and allotype studied by senior author. Holotype male of G. perplexus (Little Wood Res., Blaine Co., Idaho, 15.viii.1977, on Chrysothamnus viscidiflorus, A.B. Tabet ) in CAS (No. 14297).

Material Examined. United States. Arizona. Coconino County: 1, Flagstaff, 27.vii.1932 (T.F. Winburn, R.H. Painter) ( USNM). Colorado. Fremont County: 1, 20.vii.1959 (N. Marston ( USNM). La Plata County: 1, 13 mi. E Durango, 10.vii.1959 (R.H. Painter) ( USNM). Routte County: 1, 22 mi. W Steamboat Sprgs., 15.vii.1963 (N. Marston) ( USNM). Kansas. 5, Medora, sand dunes, 3.vii. (R.H. Painter) ( USNM). Nevada. Nye County: 1, Mercury, 27.vi.1964; 1, same data, 9.vii.1961; 1, same data, 12.viii.1961; 1, same data, 11.vi.1961 ( USNM). New Mexico. Catron County: Datil, 17.vii.1930 (T.F. Winburn & R.H. Painter) ( USNM); Hidalgo County: 1, 6 mi. W. Pachuca, 19.iv.1960 (R.H. & E.M. Painter) ( USNM). Utah. Millard County: 1, 46 mi. NW Delta, 4.ix.1965 (R.H. & E.M. Painter) ( USNM). Mexico. Baja California Sur: 1, Las Barracas, 23.vi.1983, on Haplopappus sonoriensis (P. DeBach) ( UCR).

Variation. With the usual color variations in the pile and tomentum; the ocellar tubercle may or may not have black hair. In the female, the lobe on the eighth tergite is often black instead of ferruginous; the basal lobes on the vaginal furca may not be developed to the same extent as described and figured.

Discussion. The paratypes listed by Painter (1932) from Port Lavaca, Texas belong to G. senilis and not G. argutus . The two species are very similar and are separated only by the genitalia. In the male of G. argutus , there is a small projection on the ventral margin of the gonocoxa, this is wanting in G. arenicola . In the females, the shape of the vaginal furca differs by the configuration of the arms of the lower half, in G. argutus they are narrow and slightly curved and without inward projecting arms ( Fig. 4 ), while in G. arenicola they are stout and straight, and there are prominent inward projecting arms ( Fig. 3 ). Evenhuis & Greathead (1999) synonymized G. perplexus (then a nomen nudum) under G. argutus based on unpublished notes in this study regarding similar configuration of the male genitalia. The description of G. perplexus by Tabet (2001) fits the characters that distinguish G. argutus and it is thus synonymized under it here.

Biology. One record of parasitization is known. Purrington & Evenhuis (2001) recorded the first record of a species of Geron from a sesiid, Synanthedon polygoni , in Oregon. Several larvae and pupae of the hosts were obtained from a low growing Gilia . Rearing of pupae produced one Geron argutus pupa. The pupa characteristically has reduced cephalic spines and short abdominal hairs. Adults have been taken at flowers of Chrysothamnus viscidiflorus, Daucus carota, Sphaeralcea sp., Haplopappus sonoriensis, Heliotus alba , Eriogonum elatum , Nepeta cataria , Salsola sp., and Psorelea sp. Females of G. argutus were observed by the junior author hovering and bobbing over a patch of catnip ( Nepeta cataria ) in Sedona, Arizona in the summer of 1988. One female was seen landing and laying three eggs on the leaf axil of a plant; then it flew away. Attempts to rear the eggs failed.

Distribution. United States (Arizona, California, Colorado, Kansas, New Mexico, Nevada, Oregon, Texas, Utah, Wyoming; Mexico (Baja California Sur, Hidalgo).

Figures

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.