Eucera tricinctella (Timberlake, 1969)
  Apoidea   Apidae   Eucera
Subgenus: Synhalonia

IDnature guide
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

This little species is similar to actuosa but differs in having the head less trans¨verse, the clypeus often with a median raised line, and the mesonotum less opaque and more closely and distinctly punctured. The ridges on the sixth sternite of the male end gradually behind instead of being abruptly truncate as in actuosa, and have a perpendicularly declivous wall only on their outer side.

Male.óBlack; small joints of tarsi brownish or ferruginous; tibial spurs pale testaceous. Labrum and mark on clypeus pale yellow; clypeal mark widely separated from margin of eyes, broadly emarginate on each side, and broadly truncate at summit. Tegulae pale amber at apex and dusky toward base. Pubescence of head and thorax ochreous above and paler beneath, but often entirely white. Hair of tergite 1 white, and that of following tergites and venter black; except some light hair on sternite 1, or sometimes narrow band at base of tergite 2, and hair on sternites 1 and 2 and more or less on sides of following segments white. Hair of legs ochreous or white, and ferruginous on inner side of basitarsi. One male (San Clemente) has pubescence fulvo-ochraceous above tinged with brown, and ochreous beneath, with very narrow and thin apical band of appressed feathered hair on tergite 5 white.

Head much broader than long; inner orbits of eye slightly divergent above. Venter strongly impressed on each side, eyes appearing broad and prominent at summit; lateral ocelli about their diameter from occipital margin and twice as far from nearest eye. Antennae slender, moderately compressed, reaching base of tergite 2; joint 3 about three-fourths as long as joint 4. Proboscis moderately long, galeae shining and almost hairless. Second submarginal cell obliquely quadrate, receiving recurrent nervure one-fourth of its length from apex. Hair of head and thorax rather long and moderately dense, that of tergite 1 very long and erect, of tergite 2 nearly uniformly and moderately short, and on following segment short with longer hairs intermixed. Clypeus moderately shining, with close, fine, shallow punctures. Mesonotum opaque, with moderately close, shallow punctures. Abdomen shining, minutely and densely punc¨tured, only slightly more sparsely on apical depressions, and apical margin of tergites 1 and 2 very narrowly bare and impunctate. Sternite 6 with strong impression on each side, terminating in small, rounded marginal lobe and bounded within by perpendicular wall of sublateral ridges; these ridges ending gradually behind and as seen in profile highest at one-third of their length from posterior end; disk between and beyond ridges minutely and thinly pubescent. Sternites 7 and 8 as figured. Parameral lobes of genital armature almost straight, moderately expanded at base, and evenly rounded at apex; hair on outer face of basal half moderately dense and short. Length 8.5-12 mm, anterior wing 6.5-8 mm.

Female.óBlack; with small joints of tarsi, tibial spurs, tegulae, and wings about as in male. Pubescence of head and thorax rather short and moderately dense, pale brownish-ochreous on mesonotum and vertex and paler beneath, or sometimes altogether more or less whitish. Hair of tergite 1 erect, whitish; bands on apical depression of tergites 2 to 4 white, with overhanging long, black hair from margin of elevated area. Base of tergite 2 with short, thin, white hair, thinner across middle of disk; base of tergites 3 to 5 with black hair. Apical band on tergite 5 black tinged with brown on middle half, and white on each side. Hair of tergite 6 brown, and hair of venter pale brown, especially fringes on sternites 3 to 5. In specimen from desert regions apical bands broader, invading raised area of disk more or less, with hair on base of tergite 2 more completely and densely white, and longer overhanging hairs more or less paler, or even whitish; apical band on tergite 5 more completely white, sometimes tinged with brown only at middle, and apical fringes of sternites white. Hair of legs white, with scopal hair tinged with ochreous and hair on inner side of basitarsi ferruginous.

Head considerably broader than long, but less transverse than in actuosa; inner orbits of eyes parallel. Vertex weakly impressed on each side; lateral ocelli about their distance apart from nearest eye and their diameter from occipital margin. Proboscis moderately long, galeae shining, almost hairless. Clypeus dullish, closely, finely, and subrugosely punctured, with sometimes slight, narrow, smooth median ridge. Frons dull, shallowly and obscurely punctured. Mesonotum opaque; scutum with rather sparse, shallow, fine punctures becoming more distinct on the more shining posterior middle of disk; scutellum densely, more sharply punctured. Abdomen minutely, densely punctured, tergite 1 more or less broadly bare and impunctate across middle of apical depression, and tergite 2 narrowly bare at apex. Pygidial plate somewhat longer than wide at base and narrowed less than one-half to rounded apex. Length about 9-11 mm, anterior wing 7.2-7.6 mm, width of abdomen 3.8-4.3 mm.

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