Geron stenos 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 : 58-60

Geron stenos Hall & Evenhuis , sp. nov.

Description. Male. Head. Front silvery tomentose, hair wanting; antenna black; scape and pedicel with white hair; first flagellomere evenly tapering from base to acuminate apex; antennal ratio: 9:3:19; face cinereous pollinose, white pilose, bare medially; silver tomentum lateral to antennal base; oral margin yellowish; proboscis projects beyond oral margin for a distance about one and one­half times head height; gena white pilose and tomentose; occiput white pilose, white tomentum on lower half; ocellar tubercle with white hair.

Thorax. Mesonotum dull black; lateral margin slightly cinereous pollinose; median longitudinal stripe not apparent; notum white pilose, yellow tomentose, tomentum scattered; pleura white pilose and tomentose; legs black with white hair and scales; halter with stem and knob yellowish; scutellum white pilose, tomentum wanting.

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

Abdomen white pilose and tomentose, tomentum on dorsum sparse, scattered; tergites with lateral margins narrowly pale; sternites with posterior margins narrowly pale.

Genitalia ( Fig. 54 ) with gonocoxa in ventral view flat, without depressions or ridges, in lateral view narrowly rectangular, ventral margin more or less straight; gonostylus short, two times longer than high, rounded apically; lateral ramus narrow, acuminate apically, coextensive with gonostylus; dorsolateral ramus large, prominent, nearly equal in length to lateral ramus.

Female. Eyes at vertex separated by about one and one­half times width of ocellar tubercle; front with pale yellow hair, tomentum golden yellow medially, silvery laterally and above antennal base; pedicel with short brownish hair apically; occiput with upper half yellow pilose and golden yellow tomentose; ocellar tubercle with black hair. Thorax. Mesonotum with median longitudinal cinereous stripe broad, nearly reaches transverse suture; notum with yellow hair, shorter black hair medially posterior to transverse suture; tomentum golden yellow, abundant; legs with mid and hind tibiae brownish to testaceous; scutellum yellow pilose, golden yellow tomentose; basicosta with pale yellow hair. Abdomen. Dorsum pale yellow pilose, tomentum golden yellow, abundant. Genitalia with projection on tergite VIII black; vaginal furca ( Fig. 23 ) simple; upper half V­shaped; lower half with arms broad, straight, subquadrate apex with shelf­like appurtenance nearly circling base of each arm.

Types. Holotype male (Cajon Junction, San Bernardino County, California, 1.vii.1982, J.C. Hall). Allotype (Cajon Junction, San Bernardino County, California, 24.viii.1953, J.C. Hall). Paratypes. California. 15, topotypic, collected with holotype; Kern County: 6, 2 mi. W Frazier Park, 11.viii.1983 (J.C. Hall); Mendocino County: 1, Low Gap Ranger Station, 20.viii.1958 (P.H. Arnaud, Jr.). Holotype and allotype deposited in USNM. Paratypes deposited in USNM, UCR, and CAS.

Variation. With the usual color variations. There are two females in the type series that have the front white tomentose, without golden scales. Some of the males have dark hair on the second antennal segment.

Discussion. This species has been collected with G. nigripes . The two species are, however, easily separated by the configuration of both the male (cf. Figs. 45 and 54 ) and female genitalia.

Biology. Immature stages unknown. Adults have been taken at flowers of Eriogonum sp.

Distribution. United States (California).

Etymology. The specific epithet derives from the Greek “ ” = narrow appearance; referring to the relatively narrow gestalt of the body of this species.

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.

FIGURES 42 – 45. Geron male genitalia. 42, G. johnsoni Painter; a, lateral view; b, tip of gonocoxa, ventral view. 43, G. monticola Hall & Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, dorsal view. 44, G. nevadensis Hall & Evenhuis, sp. nov.; a, lateral view; b, tip of gonocoxa, dorsal view. 45, G. nigripes Painter; a, lateral view; b, gonocoxa, ventral view.