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|
Probably delphinii is as closely allied to cordleyi as to any other species. Its male differs from cordleyi in having the clypeal mark much larger, with the lateral and dorsal margins of the clypeus more narrowly black, the antennae more slender, and with third about as long as wide and about one-fifth as long as fourth joint, The female resembles cordleyi or edwardsii but has the light band on second tergite thin enough across the middle to reveal a fine, dense puncturation.
Female.—Black; small joints of tarsi reddish brown; tibial spurs testaceous. Tegulae piceous, tinged with amber toward apex. Wings strongly dusky, nervures fuscous, subcosta black. Pubes¬cence ochreous, paler or whitish on face, underparts, and tergite 1. Tergites 2 to 4 each with band of appressed white hair, that on tergite 2 thin across middle of segment and broadly receding from apical margin, but denser and reaching apical margin on each side; that on tergite 2 some¬what arcuate, receding from apical margin across middle and extending forward onto disk; and that on tergite 4 covering apical depression. Base of tergites 2 to 4 densely banded with short black hair, very narrowly on tergite 2 and broadly on tergite 4. Exposed part of apical depression of tergite 2 with thin, appressed black hair, and apical margin of discal area with row of much longer, erect black hairs; similar erect hairs on two following segments although mostly pale on tergite 4. Recessed part of white band on tergite 3 margined with a few appressed black hairs. Tergite 5 with dense black hair, its apical band brown on basal half across middle and white on outer fourth on each side. Hair on each side of pygidial plate brown, becoming black at apex. Fringes of ventral segments whitish, but denser fringe on sternite 5 reddish brown except on each side. Hair of legs pale ochreous, scopal hair of hind legs white, that on inner side of basitarsi ferruginous, and dense hair at apex of hind femora and on outer side of middle tibiae pale brown.
Head very broad, inner orbits of eyes parallel. Vertex very slightly inlpressed on each side; lateral ocelli their distance apart from nearest eye. Proboscis long and reaching front coxae in repose; galeae of maxillae long, mostly shining, and with a few fine, short hairs. Second sub-marginal cell receiving recurrent nervure about one-fifth to nearly one-fourth of its length from apex. Apical depression of tergite 1 broadly bare and impunctate except on each side, and apical margin of tergites 2 and 3 very narrowly bare and impunctate across middle of segments. Pygidial plate a little longer than wide at base, with apex moderately wide and rounded. Length 12-14.5 mm, anterior wing 8.5-9 mm, width of abdomen 4.6-5 mm.
Male.—Black, with only one or two apical tarsal joints ferruginous or tinged with ferruginous. Tegulae and wings about as in female. Labrum and clypeal mark yellow, dorsal margin of clypeus black, sometimes more broadly on each side, and the yellow widely separated from margin of eyes. Pubescence ochreous, whitish on face, beneath and on base of abdomen, and long, erect, and moderately dense. Tergite 2 with short, erect white hair, intermixed with long, erect pale hairs on disk, and with suberect black hair on apical depression. Tergites 3 to 5 with short, thin whitish hair, intermixed with long, erect black hairs on disk, not concealing the surface, and with narrow bands of thin, appressed white hair across base of apical depressions, followed by a band of black hair on tergites 3 and 4. Hair of tergite 6 black, whitish apically, tipped with brown across the middle, and with many overlying long, darker hairs. Hair on each side of pygidial plate brown. Venter with thin, long whitish hair on each side of segments, and short, thin blackish hair medially. Hair of legs white, but ferruginous on inner side of tarsi.
Head much broader than long; inner orbits of eyes slightly divergent above. Vertex weakly impressed on each side; lateral ocelli about their distance apart from nearest eye. Oculoclypeal space rather wide. Antennae long, compressed, much as in cordleyi, but more slender; joint 3 on short side about one-fifth as long as joint 4. Clypeus moderately shining, with small, close, shallow punctures. Mesoscutum dull, with close, shallow, crater-like punctures, becoming well separated on middle of disk. Apical depression of tergites finely punctured and hairy, but narrow apical margin of tergites 1 to 4 and very narrow margin of tergite 5 bare and impunctate. Sternite 6 with longitudinal impression on each side of base, terminating in weak marginal bulge or lobe, and bounded inwardly by ridge which extends obliquely toward apex; disk with patch of very short, fine, brownish hair on each side of base and with equally fine, short hair between lateral ridges and margins. Sternites 7 and 8 as figured. Parameral lobes of genital armature rather short, bowed, moderately constricted medially, clavately expanded toward apex which is slightly less wide than base, and outer face of basal half with usual erect hair. Length about 12-13 mm, anterior wing 8.8-9 mm.