Extracted from: P.H. TImberlake. A Revisional Study of The Bees of the Genus Perdita F. Smith, with Special Reference to the Fauna of the Pacific Coast (Hymenoptera, Apoidea Part III). University of Caifornia Press Berkeley and Los Angeles 1958|
The type of locality of wilmattae is Florissant, Colorado, where it was collected by Dr. and Mrs. Cockerell and by S. A. Rohwer at flowers of Phacelia alba. It is related to P. zehrata as stated by Cockerell, but certainly not closely enough to have evolved directly from that species.
Male.—Head and thorax dark blue-green, the head and propodeum bluer than other parts. Mandibles except red tips, labrum, and face below level of antenna yellowish white, except clypeal dots and dark lower and outer margins of the subantennal plates; lateral marks ending acutely above level of remainder of markings. Collar of pronotum, interrupted band on hind margin of disk, and the tubercles white. Abdomen pale yellow, with five blackish bands as well as two dusky subapical marks on tergite 5; yellow bands on tergites 1 and 2 abbreviated and enclosed, and those on tergites 3 and 4 even, entire, reaching lateral margins and about equal to the subsequent dark bands, which do not quite reach the lateral margins. Legs pale yellow, with a broad blotch on posterior side of front and middle femora except at apex, a small streak on dorsal margin and spot on anterior side of these femora, the hind femora except at apex and on ventral edge, a cloud covering most of apical two thirds of hind tibiae, except at apex, fuscous, and a cloud on posterior side of front and middle tibiae more brownish. Scape white, the flagellum beneath more yellowish, a mark at apex of scape above and the pedicel and flagellum broadly fuscous above, with the three apical joints more broadly dark, the penultimate one nar¬rowly yellowish beneath and the terminal one entirely dark. Tegulae hyaline, the base whitish. Wings almost whitish hyaline, the nervures pale yellowish, the subcosta faintly brownish.
Head rotund, about as broad as long. Mandibles tapering, acute, and reaching far margin of proboscidial fossa. Facial foveae about three times longer than wide and subacute at lower end. Stigma of wings moderately narrow, the marginal cell about equally long beneath and beyond stigma. Frons tessellate, moderately shining, and with fine distinct punctures, which become rather close in area between each fovea and the adjacent antennal socket. Mesonotum polished, with fine remote punctures. Pubescence whitish, rather dense on cheeks and underparts of thorax, and thin and erect on mesonotum. Subgenital plate slightly longer than wide at base, narrowed a little less than half to apex, which is concavo-truncate. Aedeagus rather similar to that of sebrata, but basal orifice of caulis much smaller, the apex of caulis with a deep V-shaped emargi-nation above, and the parameral lobes narrowed to apex as seen from above. Length, 3.5-4.5 mm.; anterior wing, 2.8-3.2 mm.
Female.—Head and thorax dark green. Mandibles except the testaceous and reddish apical half, clypeus, trianuglar lateral marks reaching level of foveae, and two supraclypeal spots white; clypeus with usual pair of dark dots and two small testaceous brown spots on upper part of disk. Collar of pronotum, interrupted band on hind margin of disk, and the tubercles white. Abdomen pale yellow, with base of tergite 1 and bands at junction of tergites 1-2 to 4-5 fuscous; basal part of bands on tergites 2 to 4 produced backward at outer ends; fourth band reduced to a fuscous subapical spot on each side of tergite 4, the brownish apical depression of tergite 4, and a fuscous spot far to each side at base of tergite 5; yellow band on tergite 1 entire, but narrowed at outer ends. Pygidial plate testaceous brown. Legs pale yellow, with dark markings about as in male. Antennae brown, the scape and pedicel yellowish white beneath, and the flagellum pale yellowish brown beneath. Tegulae and wings as in the male, but with the sub-costa and margins of stigma more yellow than other nervures. Females from Utah and Nevada generally have the supraclypeal area black and sometimes two narrow pale brown or blackish fiubmedium stripes on disk of clypeus; yellow band on tergite 1 also much broader than in Colorado females.
Head about as broad as long, subrotund. Mandibles stout and tapering to acute apex. Facial foveae well impressed, close to margin of eyes, sometimes narrowed at upper end, and reaching from level of middle of antennal sockets about two thirds of distance to level of anterior ocellus. Pygidial plate moderately wide at base and narrowed to an almost acute point at apex. Frons smoothly and minutely tessellate, rather shiny and with minute sparse punctures. Clypeus and supraclypeal area also distinctly punctured. Mesonotum polished, with fine remote punctures. Pubescence about as in the male. Length, about 4-5.25 mm.; anterior wing, 3.2-3.5 mm.
One pair, Forissant, Teller Co., Colorado, on Phacelia alba, the female labeled "cotype" col¬lected July 21, 1906, and the male, July 9, 1907 (S. A. Rohwer) ; 1 male, Salida, Chaffee Co., Colorado, July 4, 1949 (R. H. Beamer) ; 19 males, 1 female, 22 miles west of Vernal, Uinta Co., Utah, on Cleome lutea, June 24,1950 (C. D. Michener) ; 2 males, Deseret, Millard Co., Utah, May 9, 1949 (G. F. Knowlton) ; and 3 males, 11 females, Golgonda, Humboldt Co., Nevada, June 17, 1952 (E. I. Schlinger).