Geron cressoni 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 : 26-27

Geron cressoni Hall & Evenhuis , sp. nov.

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

Thorax. Mesonotum subshining black (probably rubbed); median longitudinal stripe not evident; notum white pilose with shorter black hair medially on posterior half, a few scattered pale yellow, hair­like scales across posterior one­fourth; pleura white pilose and tomentose; legs black with white hair and scales; halter with stem and knob whitish yellow; 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 whitish yellow tomentum; side and venter white tomentose; tergites and sternites entirely black.

Genitalia ( Fig. 36 ) with gonocoxa in ventral view flat, without pits or ridges, in lateral view elongate­ovoid with a small projection near apex; gonostylus short, rounded apically; lateral ramus narrow, apically pointed, coextensive with gonostylus; dorsolateral ramus narrow, apically pointed, nearly equal in length to lateral ramus.

Female. As in male except for the following: Head. Eyes at vertex separated by about one and one­half times width of ocellar tubercle; front with white hair and scales; occiput with white tomentum on upper half. Thorax. Mesonotum velvety black, cinereous pollinose laterally; median longitudinal stripe reaches slightly beyond transverse suture; notum with yellow tomentum; legs with mid and hind tibiae and basitarsi ferruginous;; fore tarsi with palynophilic setae; scutellum with yellow tomentum. Abdomen. Dorsum with yellow tomentum. Genitalia with posterior projection of tergite VIII black; upper half of vaginal furca ( Fig. 7 ) narrowly V­shaped; lower half with strut narrow, curved, enlarged apically and with a small inward and slightly upward projecting appendage.

Types. Holotype male and allotype (Glade Park, Mesa County, 6,000 ft., Colorado, 6.vi.1959, E.M. & R.H. Painter). Paratypes. Colorado. Mesa County: 8, topotypic, collected with types; 16, Deerfield, 24.viii.1940 (R.H. Painter). Washington. Benton County: 2, Rattlesnake Ridge, Hanford A.E.C. Res., 10.viii.1967 (W.W. Cone). New Mexico. Catron County: 2, Datil, Cont. Divide, 17.vii.1932 (R.H. Painter), Arizona. Santa Cruz County: 53, Madera Canyon, 1.vi.1961 (R.H. & E.M. Painter). Cochise County: 12, Pinery Canyon, Chiricahua Mts., 19.v. 961 (R.H. & E.M. Painter); 13, Cave Creek, Chiricahua Mts., 19.v.1961 (R.H. & E.M. Painter); 6, 11 mi. NE Corrizo, 19.v.1961 (R.H. & E.M. Painter); 5, [no further data], 20.v.1961 (R.H. & E.M. Painter); 7, Bear Canyon, Santa Catalina Mts. , 13.v.1961 (R.H. & E.M. Painter); 1, Portal, 13.viii.1972 (S.I. & S.L. Frommer). Pima County : 1, 25 mi. SE Sells, 1.viii.1932 (R.H. Painter). Holotype and allotype deposited in USNM. Paratypes deposited in USNM and UCR.

Variation. The only variations noted have been those of the intensity of the yellow color of the tomentum and in the color of the mid and hind tibiae.

Discussion. This species appears to be much like G. stenos , sp. nov. The two may be separated not only by the differences in the male and female genitalia but also by the much lighter yellow color of the tomentum in G. cressoni , sp. nov.

Biology. Immature stages and flower preferences unknown.

Distribution. United States (Arizona, Colorado, New Mexico, Washington).

Etymology. Named for Ezra Townsend Cresson, Jr. (1876–1948) in honor of his contributions to the knowledge of North American Bombyliidae and early work on North American species of Geron .

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 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.