Geron borealis 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 : 22-24

Geron borealis Hall & Evenhuis , sp. nov.

Description. Male. Head. Front with silvery white tomentum, pile wanting; antenna black; scape with white hair, pedicel with short black hair above, white hair below; first flagellomere narrow, evenly tapering from base to acuminate apex; antennal ratio: 13:5:21; face lightly cinereous pollinose with white hair, bare medially, tomentum silvery white lateral to antennal base; proboscis projects beyond oral margin for a distance slightly more than two times head height; oral margin white; gena white pilose and tomentose; occiput white pilose, white tomentum on lower half; ocellar tubercle with brownish hair.

Thorax. Mesonotum velvety black, lateral margin anterior to wing base lightly cinereous pollinose; median longitudinal stripe divided, short, not reaching transverse suture; notum uniformly white pilose except for shorter dark hair medially on posterior half, tomentum pale yellow, sparse; pleura white pilose and tomentose; legs black, mid and hind tibiae slightly lighter in color, white pilose and tomentose; halter with stem and knob pale yellowish; scutellum white pilose, tomentum wanting.

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

Abdomen. Dorsum white pilose and pale yellow tomentose; side and venter white pilose and tomentose; tergites with lateral margins pale; posterior margins of sternites narrowly and vaguely pale yellowish.

Genitalia ( Fig. 34 ) with gonocoxa in ventral view flat, without pits or ridges, in lateral view rectangular, lower margin without projections; gonostylus broad, bluntly rounded apically; lateral ramus narrow, rounded apically, nearly coextensive with gonostylus; dorsolateral ramus large, broad, narrowly rounded apically.

Female. As in male except as follows: Head. Eyes at vertex separated by two times width of ocellar tubercle; front with white hair and silver white scales; occiput with pale yellow tomentum on upper half. Thorax. Mesonotum with median longitudinal stripe extending nearly three­fourths length of notum; notum with abundant yellow tomentum; legs with mid and hind tibiae ferruginous; scutellum with abundant yellow tomentum; fore tarsi with palynophilic setae. Abdomen. Dorsum with abundant yellow tomentum. Genitalia with posterior projection of tergite VIII black; vaginal furca ( Fig. 5 ) with upper arms narrowly V­shaped; lower struts broad, twisted, swollen inward medially, base rounded and turned upward.

Types. Holotype male and allotype (45 mi. N Wells, Elko County, Nevada, 8.viii.1958, R.H. & E.M. Painter). Paratypes. 32, topotypic, collected with types. Holotype and allotype deposited in USNM. Paratypes deposited in USNM and UCR.

Variation. With the usual variations. There may or may not be black hair on the second antennal segment and in some males the mid and hind tibiae are ferruginous. The size of the specimens range from 2–7 mm in length and in the smaller specimens the tomentum is entirely white.

Discussion. The female vaginal furca approaches that found in G. vitripennis Loew except that the struts on the lower half are much broader and they do not extend outward at base. In the male genitalia, the broad dorsolateral rami are characteristic for this species.

Biology. Immature stages and adult flower preferences unknown.

Distribution. United States (Nevada).

Etymology. The specific epithet derives from the Latin “ borealis ” = north; referring to the comparatively northern distribution of this species in North America.

Figures

FIGURES 34 – 37. Geron male genitalia. 34, G. borealis Hall & Evenhuis, sp. nov.; a, lateral view; b, tip of gonocoxa, ventral view. 35, G. confusus Hall & Evenhuis, sp. nov.; a, lateral view; b, tip of gonocoxa, ventral view. 36, G. cressoni Hall & Evenhuis, sp. nov.; a, lateral view; b, tip of gonocoxa, ventral view. 37, G. elachys Hall & Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, 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.