Extracted from: Timberlake P.H., (1969). A Contribution to the Systematics of North America Species of Synhalonia (Hymenoptera, Apoidea). University of California Publications in Entomology Volume 57|
S. edwardsii is a common western species which extends as far east as Boulder, Colorado, and which has been recorded by Cockerell also from Rio Arriba County, New Mexico. The type locality is California. The male is easily recognized by having the clypeal mark more strongly and squarely notched than usual, and generally (but not always, even in California) has the abdomen entirely black beyond the first tergite.
The female of edwardsii has not been well identified in the past. The female placed by Cockerell with angustior is certainly not edwardsii but, according to his description, agrees well with the species described herewith as amsinckiae. Except for Fowler's record under the name speciosa, this seems to be the only putative female of edwardsii that has been described. What I take to be the typical female is similar to cordleyi but has broader, more even abdominal bands, with base of second tergite narrowly black. S. cordleyi orophila with basal corners of second tergite more broadly black than across the middle I now believe should be placed with cordleyi, but there is so much variation and intergradation between the two forms that it is difficult, if not impossible, to determine certain specimens with certainty.
Female.óBlack; small joints of tarsi and base of claws more or less ferruginous; tibial spurs pale testaceous. Tegulae dark amber, infuscated toward base. Wings strongly dusky, nervures fuscous, subcosta black. Pubescence rather dense, pale fulvo-ochreous, varying to whitish. Hair of tergite 1 whitish, long, and erect, with patch of appressed hair on each side of apex. Tergites 2 to 4 each with moderately broad white band, that on tergite 2 moderately receding from apical margin across the middle. Band of black hair at base of tergite 2 more or less narrow and not reaching lateral margin (specimens with basal corners more or less black intergrade with cordleyi). Basal half, or more, of tergites 3 and 4 black. Hair of tergite 6 black, with apical band tinged with brown at middle, and white, tinged with pale brown, on outer third on each side. Hair on each side of pygidial plate dark brown. Apical fringes of sternites white, but hair of sternite 5 brown except far to each side, and sometimes the hair also on middle of sternite 4. Hair of legs light, scopal hair of hind legs pale ochreous, hair on inner side of tarsi ferruginous, and dense hair on outer side of front and middle tibiae and apex of hind femora pale brown.
Head much broader than long; inner orbits of eyes parallel. Vertex well impressed on each side; lateral ocelli about their own distance apart from nearest eye. Proboscis moderately long; galeae partly minutely tessellate, dullish, and virtually hairless. Second submarginal cell receiv¨ing recurrent nervure about one-fifth of its length from apex. Pygidial plate broad at base and rather narrowly rounded at apex. Clypeus densely and rather finely rugoso-punctate. Mesonotum dull, with close or dense, small, shallow punctures. Apical depression of tergite 1 broadly bare and impunctate except far to each side, and apical border of tergite 2 moderately widely bare or impunctate across middle. Pubescence of abdomen dense and appressed, concealing sculpture, the longer, more erect hairs usually pallid and inconspicuous. Length 13-14 mm, anterior wing 9-9.8 mm, width of abdomen about 5.5-5.9 mm.
Male.óBlack; small joint of tarsi and claws ferruginous; tibial spurs pale testaceous. Tegulae as in female. Wings sometimes less dusky, and nervures more ferruginous than in female. Labrum and clypeus yellow, the clypeus narrowly separated from margins of eyes and strongly and squarely notched on each side. Hair of tergite 1 long, erect, and whitish, and that of following segments mostly short and erect, usually entirely black, or white on basal half of tergite 2 and with a band of thin, white, appressed pubescence across apical part of tergites 3, 4 and 5 (some¨times with white hair only on tergites 1 and 5). Hair of tergites 6 and 7 black, or sometimes brown across apex of tergites and on each of pygidial plates. Hair of venter whitish, but blackish on sternites 4 and 5. Hair of legs pale ochreous or whitish, but ferruginous on inner side of basitarsi.
Head much broader than long; inner orbits only slightly divergent above. Vertex strongly impressed on each side; lateral ocelli somewhat closer to nearest eye than their distance apart. Antennae rather slender, but strongly compressed, reaching to tergite 3, joint 3 about one-third as long as joint 4. Clypeus moderately shining, with close, small, shallow punctures. Sculpture of thorax similar to that of female. Abdomen finely and closely punctured, apical margin of tergite very narrowly bare and impunctate. Sternite 6 with strong, longitudinal impression on each side at base, terminating in low, rounded bulge in margin, and bounded within by well-defined ridge, which is strongly elbowed and continued obliquely along lateral margins; disk shining, narrowly truncate at apex, with two basal, somewhat separated patches of short, erect hair, and with short, erect hair along outer side of submarginal ridges. Sternites 7 and 8 as figured. Parameral lobes of genital armature gently bowed, moderately wide, not much con¨stricted at middle, with apex slightly expanded and much more rounded on inner corner than outer; outer face with numerous erect fuscous hairs nearly to apex. Length 10-14 mm, anterior wing 8.1-9.6 mm.