Identification Summary: An uncommon and tricky species. Mitchell lists it as affiliated with Heminomada group species such as N. imbricata and N. luteoloides however, from molecular analyses we now know it is affiliated with Centrias group species such as N. articulata and N. rubicunda. MALES told from other species with strongly striped abdomens by its inflated wide scape (olive shaped) with the pedicel recessed entrirely into the scape; the complete yellow bands on T2-6; F1 very short and F2 very long with the short side of F1 less than half the length of F2;Underside of F3-F11 flattened and very slightly concave (not as much as N. denticulata); sternites with variable but extensive yellow on them. Size-wise, relatively small, FEMALES: Not yet clear how to differentiate these.
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 10 mm.; lateral ocelli subequally distant from margin of vertex and each other; cheeks somewhat narrower than eyes, posterior margin becoming carinate above; longer side of basal segment of flagellum slightly shorter than segment 2; mandibles rather robust, simple apically; wings subhyaline basa1ly, becoming lightly infuscated along apical margin and in marginal cell, with the usual three submarginal cells, 2nd somewhat broader than 3rd anteriorly, veins testaceous to piceous, basal vein much basad of transverse median; tegulae shining between deep, distinct and rather close punctures; posterior margin of scutellum deeply grooved medially; front coxae not spinose; apex of hind tibiae with one or two rather slender and elongate, yellowish bristles; head chiefly yellow, with a limited black area just above antennae, ocelli enclosed in an ovoid, blackened area, and posterior half of cheeks black; antennal scape yellow anteriorly, more reddish-testaceous posteriorly, flagellum more brownish-testaceous thorax largely red or yellow (possible discoloration due to cyanide); prothorax laterally, a limited area on mesopleura below, metapleura, adjacent lateral faces of propodeum, posterior face of propodeum medially, mid and hind coxae in large part, and a median line on scutum, black; tubercles and tegulae pale yellowish; femora largely testaceous, but all coxae more yellowish beneath, trochanters, tibiae and tarsi largely yellow, the spurs pale yellow; abdominal terga 1-5 with rather broad, transverse, sub- median, yellow or ferruginous bands, these occupying most of discs of 2-4; apical impressed areas broad and piceous, reddish on the more apical terga; abdominal sterna 2-5 largely yellow basally, the broadly impressed, apical margins more reddish, basal sternum with a median yellow blotch; punctures coarse, close, deep and distinct over most of head, becoming slightly finer on cheeks below, very fine and close on supraclypeal area and clypeus; scutum, scutellum, mesopleura and propodeum coarsely and quite densely rugosopunctate, rather shallowly on propodeum, becoming quite finely so on lateral faces below; discs of abdominal terga 2-4 very finely, closely and quite distinctly punctate basally, punctures becoming more minute and somewhat more widely separated toward apical margins, very minute and rather close on basal tergum medially, becoming impunctate laterally and basally; tergum 5 finely and closely punctate basally, more coarsely and sparsely so apically; pseudopygidium transverse, very short, forming the quite broad, apical margin of tergum 5, densely covered with erect, pale yellowish or whitish tomentum; pubescence very short and thin but fairly copious on head and thorax, whitish below, more yellowish above, barely visible over most of abdomen, with some longer sparse hairs on the sternal plates; apex of sternum 5 with dense lateral tufts of elongate, curved, more or less fuscous hairs which converge medially.
MALE—Length 9.5 mm.; lateral ocelli sub-equally distant from margin of vertex and each other; cheeks slightly narrower than eyes, posterior margin rounded; antennal scape much swollen, apex deeply excavated and entirely enclosing the pedicel, basal flagellar segment very short, the longer side much shorter than segment 2 which is fully twice as long as broad, median segments somewhat less elongate; mandibles quite robust, simple apically; wings hyaline basally, becoming faintly infuscated along outer margin and in marginal cell, with the usual three submarginal cells, 2nd and 3rd subequal anteriorly, veins testaceous to brownish, basal vein much basad of transverse median; tegulae shining between deep, distinct and quite close punctures; posterior margin of scutellum very slightly impressed medially; front coxae not spinose; hind femora slender and simple; clypeus, a small spot on supraclypeal area, narrow lateral facial maculae terminating at level of antennae on margin of eye, labrum, mandibles except tips, and lower end of cheeks on eye margin, bright yellow, head otherwise black; antennal scape bright yellow anteriorly, piceous posteriorly, flagellum brownish-testaceous; pronotal collar, tubercles, tegulae, two large maculations on scutellum, and a rather large anterior maculation on mesopleura, bright yellow, thorax otherwise black; front and hind coxae black in large part, legs otherwise largely testaceous, but hind femora more piceous beneath, all tibiae more or less yellow at base and apex, and tarsal segments yellow basally, becoming somewhat reddened apically, spurs pale yellow; abdominal terga 1-6 with broad, basal, yellow bands, that on tergum 1 more median and narrowly interrupted medially, occupying most of discs on 2-6, apical impressed areas more reddish; abdominal sterna 2-6 more or less broadly yellowish across discs, the broad, apical, impressed areas more ferruginous-hyaline, basal sternum with a median yellow blotch, and sternum 6 largely yellow; punctures coarse, deep, distinct and close over most of face and cheeks, coarse just below antennae, very fine, obscure and rather close on maculated areas above and on clypeus, very sparse on lower anterior orbits; scutum, scutellum and mesopleura quite densely and rather coarsely rugoso-punctate, propodeum more shallowly rugoso-punctate posteriorly, becoming much more finely so laterally and more or less shining along lower anterior margin, triangle rather smooth and impunctate below, becoming quite coarsely and irregularly rugosostriate along upper margin; pubescence short and thin but quite copious over most of head and thorax, whitish below, somewhat tinged with yellow above, barely visible on abdominal terga, the sterna with some more elongate, sparse hairs, only tergum 6 rather densely pubescent apically; basal width of pygidial plate about equal to median length, strongly narrowed apically, tip deeply incised, margins carinate, surface covered with fine, slightly separated punctures; abdominal sterna but little modified, sternum 6 triangularly acute apically, tip quite densely covered with erect, fine, yellowish hairs; sternum 8 with a slender apical process; gonocoxites of genital armature as shown (fig. 105).
DISTRIBUTION—Illinois to New York, south to the Great Smokies National Park (Tennessee or North Carolina), April and May.
FLOWER RECORDS—Robertson (1929) records dentariae on Dentaria, Erythronium, Mertensia and Salix.
The description above of the female of this species is based on a specimen collected with a male in the Great Smokies National Park and received from R. R. Dreisbach.