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 8-12 mm.; black, tegulae yellowish-hyaline, legs beyond the trochanters reddish-testaceous; eyes slightly convergent below; lateral ocelli subequally distant from margin of vertex and each other, somewhat more distant from eyes; cheeks considerably narrower than eyes, subcarinate posteriorly, strongly narrowed below, angulate below, but this area obscured by short dense pubescence; clypeus nearly flat, apical margin straight, densely fringed with rather short, pale pubescence; median length of labrum about equal to basal width; median tooth of mandible well developed, somewhat nearer apical tooth than inner angle; punctures deep and distinct, distinctly but not widely separated across vertex, close, coarse and irregular on cheeks above, becoming finer and more obscure below; some irregular smooth spaces surrounding anterior ocellus, but this area otherwise rather coarsely, irregularly punctate, a narrow, smooth, impunctate area near top of eye on inner margin; face below antennae irregularly rugose, the clypeus quite finely so; pubescence entirely pale, short, rather dense around antennae and on cheeks below, pleura with rather distinct, anterior and posterior fringes of white hair, scutello-mesothoracic suture with a tomentose line, and scutum anteriorly with a pair of transverse, tomentose bands that are widely interrupted medially; propodeum largely covered with elongate, whitish hairs; transverse carina of tubercles erect and conspicuous, extending but very slightly along anterior margin of scutum; posterior margin of scutellum nearly straight, posterior face quite distinct, densely white tomentose; axillae quite robust, acute apically, projecting quite conspicuously from margin of scutellum (fig. 64); front coxal spines short but quite distinct, broadly triangular, with narrowly acute apex; wings lightly infuscated, recurrent veins reaching 2nd submarginal cell subequally distant from base and apex; punctures of scutum close, coarse, deep and distinct, being slightly separated only in center of disc, becoming somewhat finer and densely crowded between notaulices and tegulae, scutellum and axillae somewhat more finely rugoso-punctate; pleura with coarse, confluent punctures, being almost reticulate; lateral faces of propodeum smooth but dull, posterior face somewhat more shining, with very minute and close, obscure punctures, dorsal area more velvety, becoming more finely substriate along upper margin; basal abdominal tergum shining, deeply punctate, the punctures somewhat sparse in center, very close at extreme sides, apical margins slightly depressed, with a complete, white, apical fascia; terga 2 and 3 with complete, rather deep, transverse grooves, punctures basad of these quite evenly distributed, deep, distinct and quite close, the apical portion of disc very sparsely punctate medially, becoming rather closely punctate at extreme sides, the grooves medially somewhat nearer the apical margin; margins of discs narrowly depressed, with entire, whitish, apical fasciae, these becoming very broad and dense laterally; tergum 4 with a shallow, transverse groove and 5 slightly impressed in the same relative position, punctures basal to this quite uniformly close, deep and distinct, the more apical areas almost impunctate medially, but becoming rather closely punctate at each side, apical margins narrowly depressed, with entire, white fasciae; tergum 6 subtriangular in outline, sides very slightly incurved at about mid point in length, but not at all angulate, with an obscure, median line which continues toward apex as a somewhat elevated ridge, rather deeply excavated on each side of this, the tip narrowly rounded, sides slightly grooved, punctures of basal part deep, distinct and moderately coarse, becoming line and densely crowded toward apex (fig. 65); sternum 6 rather narrow, quite deeply notched on each side toward apex, this part somewhat longer than width at the notches; abdominal sterna 1-4 somewhat shining, very closely, deeply and quite coarsely punctate, apical margins slightly depressed, rather broadly yellowish-hyaline, densely white tomentose, forming complete but rather loose fasciae; sternum 5 subtriangular in outline, basal portion deeply and closely punctate, but punctures becoming fine and dense toward the impunctate and finely roughened, subacute apex, sides fringed with dense, white tomentum.
MALE—Length 8-10 mm.; black, tegulae yellowish-hyaline, legs largely brownish-ferruginous; eyes rather strongly convergent below; lateral ocelli slightly nearer margin of vertex than to eyes, and slightly nearer each other than to margin of vertex; cheeks very slightly narrower than eyes, subcarinate posteriorly, with a bare, deeply concave and elongate area below which has a marginal fringe of dense, whitish pubescence; clypeus nearly flat, apical margin nearly straight, entire surface densely covered with yellowish pubescence which obscures the surface; median length of labrum about equal to basal width; middle tooth of mandible well developed; punctures quite coarse, deep and distinct, well separated across vertex, becoming sparse just back of lateral ocelli and toward upper margin of eye, cheeks becoming somewhat more finely and closely punctate below, anterior ocellus surrounded in part by a somewhat elevated impunctate area, and narrow margin at upper end of eye impunctate, face otherwise finely and densely rugose beneath the dense pubescence; pubescence of face yellowish-white, subappressed in part, that on cheeks more whitish, short and thin; pleura with marginal fringes of whitish hairs, the scutello-mesothoracic suture with a line of fine tomentum, and scutum anteriorly with a pair of transverse, somewhat curved tomentose lines which are widely separated medially; propodeum largely covered with more erect and fine, pale pubescence; transverse carinae of tubercles erect but largely obscured by a fringe of yellowish hairs; posterior margin of scutellum nearly straight, posterior face rather sharply delimited from dorsal face. rather densely pubescent; axillae quite robust, acute apically, projecting quite conspicuously from sides of scutellum; coxal spines well developed, somewhat flattened, narrowly rounded apically, densely pubescent posteriorly and laterally; wings subhyaline basally, becoming faintly infuscated apically, 1st recurrent vein reaching 2nd submarginal cell much nearer base than 2nd does to apex; scutum very coarsely, closely and deeply punctate, punctures nearly contiguous throughout, becoming somewhat more dense laterally; scutellum and axillae rather coarsely rugoso-punctate; pleura with rather shallow but coarse, sub-continuous punctures; lateral faces of propodeum smooth but dull, posterior face somewhat more shining, with rather close, minute, obscure punctures, dorsal area rather broadly velvety, becoming obscurely rugoso-striate along upper margin; basal abdominal tergum shining but closely and deeply punctate, apical margin somewhat depressed, with an entire whitish fascia; terga 2 and 3 with entire, transverse grooves which are clearly evident at mid point of disc, punctures basad of the grooves deep, distinct, quite coarse but close and regular, the punctures beyond the grooves more irregular, very sparse and coarse medially, where the surface is shining, becoming finely and densely rugose just behind the rather distinct foveae, these somewhat elongated, margined with a shining impunctate ridge, apical margins of these terga densely white fasciate; terga 4-6 more or less densely fasciate at base, 4 and 5 with an apical, dense, whitish fascia which is somewhat narrowed medially, punctures quite coarse, deep and distinct, slightly but not widely separated medially; surface of tergum 6 very closely, deeply and rather finely punctate, a deep, median excavation just before tip, dorsal protuberances divergent, rather narrowly rounded ventral spines more nearly parallel-sided, rather short and blunt, lateral spines well developed, subacute (similar to sayi, fig. 66); sterna 1-4 shining, with coarse, deep and quite uniformly close punctures, apical margins rather broadly depressed, yellowish-hyaline, densely white tomentose, forming conspicuous fasciae; disc of sternum 4 not emarginate medially, depressed rim without a conspicuous, median emargination; sternum 5 largely retracted, apical margin nearly straight; sterna 6 and 8 entirely retracted; gonocoxites only slightly exceeding penis valves, rather broadly compressed, with scattered and rather conspicuous, elongate hairs.
DISTRIBUTION—British Columbia and California, east to Quebec, the New England states, and Florida; May to October.
FLOWER RECORDS — Asclepias, Baptisia, Cuscuta, Eriogonum, Fragaria, Geranium, Helenium, Hieraceum, Melilotus, Oenothera, Phaseolus, Rhus, Rubus, and Rudbeckia. Robertson (1929) lists the following additional host genera: Amorpha, Apocynum, Aster, Bidens, Blephilia, Boltonia, Brauneria, Coreopsis, Crotalaria, Desmodium, Dianthera, Eryngium, Eupatorium, Helianthus, Heliopsis, Krigia, Lepachys, Lippia, Lobelia, Lythrum, Nepeta, Petalostemum, Polytaenia, Psoralea, Pycnanthemum, Solidago, Symphoricarpus, Trifolium, Verbena, Verbesina and Veronica.
HOST—J. T. Medler has reared 8-dentata from nests of Megachile centuncularis and M. mendica. It is also recorded from nests of M. brevis by Hicks (1926) and Michener (1953).
Reprinted with permission from: Baker J. R. 1975. Taxonomy of five nearctic subgenera of Coelioxys (Hymenoptera: Megachilidae). The University of Kansas Science Bulletin 50(12):649-730.
FEMALE. Agrees with descriptions and figures of Coelioxys rufitarsis and C. novomexicana except as follows: (1) Length 7-12 mm; (2) integument black; scape, pedicle, apical portions of metasomal sterna black to dark ferruginous; tegula, tibiae, tarsi fulvous; femora black to fulvous; (5) clypeus slightly convex clypeal margin straight or slightly emarginate as in Figure 22B; (22) tergum 6 with lateral angles variable (Fig. 24D-I); (23) sternum 6 with apex variable, broadly ovate to lanceolate (Fig. 24D-I).
MALE. Agrees with descriptions and figures of Coelioxys rufitarsis and C. novomexicana except as follows: (45) tergum 6 with dorsal spines usually slightly more slender than shown in Figure 25G.
HOST RECORDS. Fox (1900) reared Coelioxys octodentata from a nest of Megachile mendica, a record repeated later by Medler (1965). Hicks (1926) reared C. octodentata from a nest of M. brevis, repeated later by Michener (1953) and Baker (1971). Medler (1958) reared this bee from a nest of M. centuncularis, and Hobbs (1956) reared it from a nest of M. perihirta. Medler and Lussenhop (1968) reported that D. H. Pengelly reared C. octodentata from a nest of M. texana. A new host record is a female of C. octodentata labeled: Cornish, Utah, IX-10-59, reared from cell of Meg. onobrychidis. Another new host record is from three females from College City, California reared from three nests of M. rotundata by Dr. R. W. Thorp (as would be expected, these bees are small, 7-8.5 mm).
DISTRIBUTION AND SEASON OF FLIGHT. Coelioxys octodentata ranges from southern Canada to the southern United States (Fig. 32). In the southwestern portion of its range the distribution of C. octodentata overlaps with that of C. novomexicana (compare Figs. 31 and 32).
This bee is in flight at least from May 8 (Kansas) to October 22 (central California).
HABITAT. In the western United States, Coelioxys octodentata has been collected from a variety of areas classified as needleleaf forests and broadleaf and needleleaf forest combinations. This bee has also been taken from a number of western shrub lands, western grasslands and western shrub and grassland combinations. Elsewhere this bee has been taken from central and eastern grasslands, grassland and forest combinations, and eastern broadleaf and broadleaf and needleleaf forests.
However, more specific habitat observations have been reported for Coelioxys octodentata (Hicks, 1926; Michener, 1953). The host bee, M. brevis, nests in open meadows and unshaded sites usually in, on or near the ground. These are also types of areas in which C. octodeatata is found flying near the ground and from which nests containing C. octodentata larvae have been recovered (Hicks, 1926; Michener, 1953). Occasionally M. mendica nests in the ground at the edges of open areas, a situation which C. octodentata might exploit.
GEOGRAPHIC VARIATION. Six
characters of Coelioxys octodentata were analyzed for geographic variation: size, degree of angulation of the sixth tergum, density of the medial fascia of the first metasomal tergum, leg color, punctation of the vertex, and degree of elongation of the sixth metasomal sternum. Females were used for this analysis as the males in southern Oregon, California, northern Arizona and New Mexico, Utah, and Colorado cannot be distinguished from those of C. novomexicana. In Figure 32 each of the six sides of a symbol summarizes data on one character in the form of a histogram for the group of bees from the area indicated (a key to characters and scale appears in the upper right portion of the map).
Size varies markedly even in bees from the same general area (in Fig. 32 size was scored as small, 0-9.0 mm; medium, 9,1- 10.9 mm; large, 11-12 mm). Perhaps, as was postulated for Coelioxys juneraria and C. novomexicana, size is an expression of host size in C. octodentata. Degree of development of the lateral
angle of the apical tergum does not seem to vary geographically except perhaps for bees from the southeast. Bees from the East with well developed angles and apical sterna were formerly considered to be Coelioxys atlantica. Bees from the West with well developed angles and apical sterna and medial fasciae of the first metasomal tergum were considered to be C. coquilletti. Bees intermediate in all conditions were considered to be C. octodentata throughout the distribution. Bees, especially small specimens, with poorly developed sixth tergal angles, apical sterna, and medial fasciae were formerly considered to be C. salinaria or C. pratti (a misidentification; original description of C. pratti emphasizes the long, brown ocular hairs). Specimens with poorly developed angles and long sterna and specimens with extreme angles and short sixth sterna (Fig. 24D-I) represent mixed conditions among the extreme examples. Most bees from the Southeast have the lateral angles moderately developed (Fig. 32).
The medial fascia of the first metasomal tergum in general is poorly developed in the Southeast (minimum in Fig. 32) but well developed in large specimens from the northwestern and western United States (maximum in Fig. 32). In the West there seems to be a correlation between size and density of this medial fascia in that larger bees (formerly considered to be Coelioxys coquilletti) usually have medial fasciae which are more dense and contain more squamose setae than those of smaller bees (formerly considered to be C. crassula and C. octodentata). However, if only the larger bees are considered, the medial fascia of the first metasomal tergum gradually becomes less dense and the proportion of squamose setae drops as a cline across the northern United States from west to east.
Leg color, especially color of the femora, varies from black to fulvous with the color of most specimens intermediate (ferruginous). Bees of the eastern United States have fulvous to ferruginous legs whereas western specimens vary from fulvous to black with both large and small bees displaying both extremes of leg color.
Punctation of the vertex varies from closely punctate to a condition in which impunctate areas occur lateroposteriorly to the ocelli (in Fig. 32 this character was scored as impunctate areas, minimum; closely punctured, maximum). Most bees were intermediate or with impunctate areas, but a few (mainly from the North. cast) were closely punctured.
The apex of the female sixth sternum seemed to be highly variable in contrast to most species of North American Coelioxys in which the apex of the sixth sternum may be uniform throughout the whole series. In C. octodentata, however, the apex of the sixth sternum ranged from broadly ovate (Fig. 241, minimum in Fig. 32) to lanceolate (Fig. 24D, maximum in Fig. 32).
Females with maximum lanceolate apices of the sixth metasomal sternum were generally medium to large, although some small bees had moderately lanceolate apices (as in Fig. 24G-H).
The large specimens of this species are most likely to be confused with Coelioxys rufitarsis although the ocular hairs are short and the medial fascia of the first metasomal tergum is composed of short, appressed setae in C. octodentata (long ocular hairs and long, erect setae on tergum one in C. rufitarsis). In the West, females of C. octodentata differ from those of C. novomexicana by their almost straight clypeal margin (bibbed in C. novomexicana) although males of C. octodentata are not separable from those of C. novomexicana. Females of C. octodentata differ from females of C. sayi in the same way as from females of C. novomexicana and males differ from C. say: by the well produced posterior margins of the gradular grooves of metasomal terga two and three (posterior gradular margin almost obliterated medially in males of C. sayi).