Reprinted with permission from: Mitchell, T.B. 1962 Bees of the Eastern United States. North Carolina Agricultural Experiment Station Technical Bulletin No. 152.
FEMALE—Length 7-8 mm.; entirely black; face considerably longer than distance between eyes above; eyes slightly convergent below; lateral ocelli slightly nearer each other than to eyes, still nearer margin of vertex; clypeus very slightly convex, apical margin somewhat produced, practically straight, mandibles only slightly broadened apically, distinctly tri- dentate, median tooth only slightly nearer apex than to inner angle; cheeks slightly broader than eyes; wings subhyaline basally, becoming faintly infuscated apically, stigma brownish-piceous, veins more brownish-testaceous; tegulae shining, piceous, with punctures hardly evident; legs entirely black, spurs pale yellow; pubescence entirely pale, rather short and thin, but quite copious around antennae, on face below, and over much of thorax, the dorsal pubescence elongate but very thin; abdominal terga 1-4 with narrow, whitish, apical fasciae, these widely interrupted medially on 1 and 2, usually entire on 3 and 4, 5 only sub-fasciate, discal pubescence exceedingly short and inconspicuous, hardly visible on the more basal terga, but becoming quite dense and subappressed on tergum 6, apical margin on 6 very slightly reflexed and shelf-like; scopa entirely yellowish-white; punctures quite deep and distinct, rather coarse and close in general, very close and somewhat finer on most of face, including vertex, becoming densely crowded on clypeus, close and fine on cheeks, but lower surface shining and impunctate, the two areas separated by a row of long, curled, whitish hairs directed toward the hypostome; scutum and scutellum shining between deep and distinct punctures, these finer and rather sparse in center of scutum, otherwise quite close, almost crowded on pleura; propodeum dull and tessellate, punctures very shallow and indefinite; abdominal terga shining, punctures minute and sparse on terga 1 and 2 medially, becoming close at extreme sides, somewhat coarser and closer on 3 and 4, uniformly fine and close on 5 and 6.
MALE—Length 6-8 mm.; entirely black; face considerably longer than distance between eyes above; eyes slightly convergent below; antennal scape slender and rather short, not much if any exceeding diameter of flagellum, pedicel completely exposed, flagellar segments slender and simple, considerably longer than broad; lateral ocelli subequally distant from eyes and each other, somewhat nearer margin of vertex; clypeus slightly convex, apical margin slightly produced, nearly straight, disc covered with relatively elongate, erect, whitish pubescence; labrum shining, rather flat and unmodified, median length somewhat less than basal width; mandibles bi-dentate; cheeks subequal in width to eyes; wings subhyaline, veins and stigma brownish-testaceous; tegulae shining, piceous to black, with minute, scattered punctures; legs entirely black, spurs pale yellow; tergum 7 exposed apically, margin rather broadly rounded, with a slight, subapical impression; sterna 1-5 exposed, apical margin of 2 broadly outcurved, with a low but distinct, subapical ridge, 2 with a quite deep, median emargination which is conspicuously fringed, 4 nearly straight apically, 6-8 retracted, form as shown (fig. 25); genital armature as shown; pubescence entirely pale, rather thin in general, somewhat more copious over head and thorax, rather dense on lower half of face and on cheeks below; abdominal terga 1-5 white fasciate apically, these interrupted medially, but dense at sides; punctures rather fine but deep and distinct over most of head and thorax, densely crowded over most of head, but lower surface of cheeks shining and more minutely punctate and more densely pubescent; scutum and scutellum shining, punctures slightly separated in center of discs, otherwise rather close, quite close over most of pleura, becoming rather sparse on a limited area just beneath wing base; propodeum dull and tessellate, punctures indistinct; abdominal terga 1-5 shining, punctures minute and quite sparse medially, becoming somewhat closer on the more apical terga, rather close at sides, even on basal tergum; tergum 6 rather closely but irregularly punctate.
TYPES—Holotype: Male, Douglas Co., Kans., May 11, 1949 (R. H. Beamer, on Amorpha fruticosa). Allotype: topotypical [both Univ. Kans.]. Paratypes: 6 ♂♂, 1 ♀, topotypical 3 ♂♂, 5 ♀♀, Miami Co., Kans., May 20 & 27, and June 1, 1951 (C. D. Michener, on Amorpha fruticosa); 2 ♀♀, 5 mi. south and 6 mi. SW of Lawrence, Kans., June 10 & 12, 1950 (C. B. Michener and J. R. White, on Amorpha fruticosa); 1 ♂, Hamilton, Ga., May 19, 1931 (P. W. Fattig). Paratypes are in collections of the University of Kansas, the U. S. National Museum and the author.
The author is indebted to C. B. Michener not only for the material upon which the description of micheneri is based, but for critical observations concerning the characters, distribution and correlation of the sexes in the related species of Robertsonella.