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Megachile rugifrons (Smith, 1854)
Chelostoma rugifrons Smith, 1854; Chelostomoides rugifrons (Smith, 1854); Megachile rufimanus Robertson, 1891; Chalicodoma (Chelostomoides) rugifrons (Smith, 1854)

Life   Insecta   Hymenoptera   Apoidea   Megachilidae   Megachile
Subgenus: Chelostomoides

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 13-15 mm.; abdomen elongate and parallel-sided; entirely black, including tegulae and legs, spurs more testaceous; eyes slightly divergent below; clypeus much modified, outer face very short, angulate at each side, median area evenly sloped to articulation of labrum, upper portion of this shallowly punctate, apparently representing outer face, while the lower, impunctate, shining area represents the thickened edge; mandibles very slender and elongate, with an obscure, inner, basal angle, and with three small apical teeth (fig. 60); labrum much elongated, slightly narrowed just before apex, median length much greater than basal width; lateral ocelli very much nearer eyes than to margin of vertex; cheeks somewhat broader above than eyes, much narrowed below; punctures of vertex and cheeks coarse, deep and rather close, becoming somewhat crowded and irregular on cheeks below, very slightly separated on vertex medially; face below ocelli rather finely and densely punctate, becoming fine and densely crowded laterally, supraclypeal area shining, with fine, irregular and rather sparse punctures, lateral areas of clypeus with very fine, irregular but rather close punctures; pubescence white on face and cheeks, somewhat more yellowish on clypeus, labrum and cheeks below, short but rather dense around antennae and on face laterally, thin on cheeks, and vertex with short, erect, very inconspicuous, fuscous pubescence; thorax with thin, white pubescence laterally and posteriorly, this quite dense around tubercies and behind wing bases, scutum with very short, erect but rather thin, fuscous pubescence, this becoming more whitish anteriorly, and with a pair of fine, slightly oblique, anterior lines of white tomentum, scutellum with somewhat longer, erect, fuscous hairs; scutum with deep and distinct, rather fine and close punctures throughout, being slightly separated only in center posteriorly, scutellum with more widely separated and considerably coarser punctures, those on axillae very fine and close but distinct; punctures of pleura rather shallow but quite coarse, uniformly close, becoming crowded above; lateral faces of propodeum somewhat smoother, with very fine, close, shallow punctures, posterior face dull, with close, fine punctures; all basitarsi considerably shorter and narrower than their tibiae; tegulae minutely and closely punctate; wings subhyaline, veins brownish-piceous; abdominal terga 2-4 rather deeply depressed across base, these depressions largely devoid of pale tomentum, basal margin distinct, subcarinate, apical margins of 2-4 with entire, white fasciae, these narrow medially but quite dense laterally, margins only slightly depressed except at extreme sides; basal tergum with very thin and rather short, pale pubescence, the lateral, apical angles becoming very densely white tomentose, punctures deep and distinct, but rather fine and only slightly separated; discal pubescence of following terga very obscure, short and sparse, largely pale on 2-4, the punctures deep, distinct but fine and quite sparse medially becoming quite coarse and close laterally; tergum 5 with a shallow indefinite, sub-basal impression which is not at all carinate, apical margin rather deeply depressed but not fasciate, punctures fine and rather close, slightly separated only in center, with rather copious but very short, erect, blackish pubescence; tergum 6 nearly straight in profile, with an abrupt, apical lip, quite densely white tomentose across base, otherwise with short, erect, black hairs, punctures rather fine and densely crowded; sternum 6 deeply and very closely punctate, well covered with short, dark, scopal hairs, these becoming somewhat paler toward base, the apex narrowly subtruncate; scopa otherwise pale yellowish-white, sterna uniformly very closely, deeply and rather coarsely punctate, apical margins narrowly depressed, very narrowly hyaline; sternal fasciae absent.

MALE—Length 9-10 mm.; black, tegulae more testaceous, front tibiae bright yellow anteriorly, mid and hind legs largely dark, spurs pale yellow; eyes subparallel; median third of clypeal margin straight but very slightly produced; mandibles 8-dentate, without an inferior process; antennae markedly slender and elongate, flagellum somewhat reddened beneath; lateral ocelli slightly nearer eyes than to margin of vertex; cheeks slightly narrower than eyes; punctures of vertex and cheeks very coarse and deep, slightly separated on vertex medially, becoming relatively close and irregular on cheeks below; face below ocelli densely rugoso—punctate, becoming very minutely roughened or tessellate laterally and on supraclypeal area, clypeus very finely and densely rugoso-punctate beneath dense pubescence; face and clypeus with rather copious, elongate, white pubescence, largely hiding surface, cheeks below with elongate but somewhat thinner white pubescence, this becoming shorter above, thin, elongate, erect and more yellowish on vertex; thorax with rather short, white pubescence laterally and posteriorly, quite dense around tubercies and behind wing bases; scuturn with erect, somewhat shorter, dark hairs, these becoming pale anteriorly, with a pair of very short anterior lines of white tomentum, scutellum with somewhat longer, erect, largely pale hairs; punctures of scutum close, deep and distinct throughout, somewhat finer laterally, and to a slight degree separated near center posteriorly, scutellum with somewhat coarser, more widely separated punctures, these fine and close on axillae; pleura dull, punctures shallow but very coarse and close; lateral faces of propodeum rather dull, punctures close but shallow and obscure; front coxae with neither spines nor tubereles, quite densely pale pubescent; front tarsi rather pale, but slender and simple, with a rather short and thin, pale, posterior fringe; anterior face of front tibiae bright yellow, in some contrast to the outer, somewhat more reddened face, and front femora yellowish on apical portion of anterior face; mid tibia! spurs well developed, the mid and hind tarsi slender and simple; tegulae minutely and closely punctate; wings subhyaline, veins brownish-piceous; abdominal terga 2-4 rather deeply grooved across base, these grooves with conspicuous, white tomentum, basal margins more or less carinate, apical margins of terga rather broadly depressed, yellowish-hyaline, only obscurely fasciate laterally if at all; basal tergum rather thinly white pubescent, subfasciate apically at extreme sides, punctures deep and distinct, rather coarse, becoming fine along apical margin; discal pubescence of terga 2-4 very short, thin and inconspicuous, hardly evident, punctures deep and distinct, well separated medially, becoming much coarser and closer at extreme sides; tergum 5 densely tomentose across base, apical margin narrowly but deeply depressed, entirely dark and not fasciate, surface somewhat shining medially, with fine, well separated punctures, these becoming coarse and close laterally and apically; tergum 6 narrowly but densely, white tomentose across base, surface dull, very densely and rather finely rugose, carina hardly evident, with a shallow, barely perceptible, median emargination, median apical teeth broadly carinate, much nearer the small but acute lateral angles than to each other; tergum 7 transverse, very low and inconspicuous, not at all produced medially; sternum 4 entirely retracted but unmodified; sterna 1-3 exposed, quite closely and deeply punctate, rather coarsely so laterally, becoming fine medially, apical margins rather narrowly depressed and yellowish-hyaline, 1 and 2 with dense apical fringes of rather elongated, white hairs, the 3rd only inconspicuously fringed laterally; setose area of sternum 5 transverse, subapical setae robust, abruptly flexed and broadly dilated apically, the more lateral setae very long, directed basally (fig. 61) ; setose areas of sternum 6 not divided medially, closely set with apically flexed, slightly dilated setae, the more lateral of these longer; apical lobe of 6 slightly broader than long, subtruncate; gonocoxites much narrowed above base, then dilated to the robust, laterally flexed tips (fig. 62).

DISTRIBUTION — Nebraska to Michigan and North Carolina, south to Texas and Florida, April to July.

FLOWER RECORDS — Erigeron, Hypericum, Pontederia, Tephrosia, Vaccinium and Verbena. Robertson (1929) records rugifrons (as rufimanus) on Apocynum, Blephilia, Coreopsis, Lobelia, Nepeta and Psoralea.

Scientific source:

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FamilyScientific name @ source (records)
Fabaceae  Baptisia tinctoria @ AMNH_BEE (1)

Cracca virginiana @ UCRC_ENT (1)

Melilotus officinalis @ CUIC_ENT (1)

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Updated: 2019-10-14 10:26:28 gmt
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