Reprinted from: Rightmyer MG, Griswold T, Arduser MS (2010) A review of the non-metallic Osmia (Melanosmia) found in North America, with additional notes on palearctic Melanosmia (Hymenoptera, Megachilidae). ZooKeys 60 : 37 – 77 . doi: 10.3897/zookeys.60.484|
Females of O. laticeps are distinguished from all other North American non-metallic Osmia by the following characters of the mandible (Figs 5, 6): the apical margin is only slightly broader than the median width, the third tooth is relatively broad and not strongly separated from the fourth tooth, and the condylar and outer ridges converge apically; in addition, they are diagnosed by their strongly granulose propodeal triangle and relatively short apical impunctate bands on T2 and T3.In the Palearctic, O. laticeps is most similar to O. uncinata. In addition to the characters mentioned in the key (above), the following characters can be used to distinguish females of the two species (most characters fi rst noticed by Haeseler 1999): in O. laticeps, the clypeus has more plentiful pale hairs than black hairs, and these pale hairs are about the same length as the black hairs. In O. uncinata, the clypeus has nearly the same amount of black hairs as pale hairs, and the black hairs are distinctly longer than the pale hairs. Th e malus of the foretibia has the apical tip evenly tapering to a point in O. laticeps, while in O. uncinata the tip is slightly more blunt. Th e outer hind tibial spur is more strongly downcurved in O. uncinata than in O. laticeps. Additionally, the hairs of the hypostomal area are denser and more strongly incurved in O. laticeps than in O. uncinata. In both the Nearctic and Palearctic, males are known by the non-swollen gonoforceps (outer margin preapically only weakly widened, about the same width as the gonoforceps basal and distal to this preapical point of infl ection), and the relatively unmodifi ed S4 (Fig. 61): the apical margin of S4 is evenly convex and midapically on S4 the relatively short, unmodifi ed hairs arise from regularly-spaced tubercles (not forming distinct, sublateral tufts of apically hooked hairs).
Figs 5, 6, 54, 58. Total length: 8.4–9.0 mm; forewing length: 6.0–8.1 mm; length of lateral ocellus to preoccipital margin 0.6–0.7 mm; length of lateral ocellus to compound eye 0.6–0.7 mm. Color: Dark brown to brown-black, sometimes with reddish overtones especially on mouthparts, labrum, mandible, fl agellar segments, legs, and apical margins of T1– T5. Wings mostly clear to weakly infuscate, except moderately infuscate along dorsal half of marginal cell. Pubescence: Clypeus below apical margin with lateral tuft of golden, medially directed hairs. White to golden, minutely branched hairs on most of body except as follows: brown, simple hairs interspersed with pale, branched hairs on clypeus, sometimes interantennal area and near ocelli, gena ventrally and along compound eye, outer surfaces of femora and tibiae (especially on fore and midlegs); dark-brown, simple hairs only (no branched hairs) on mouthparts, labrum, inner surfaces of legs (golden on tarsi), outer surfaces of hind tibia and all tarsi, T2–T6, and scopa; brown, short, simple hairs evenly covering forewing. Galea and basal two labial palpal segments with hairs on lateral margins straight, 0.2–0.3 OD in length. Labrum with long hairs arranged in two curved, transverse rows, along subapical margin and approximately at midpoint, with additional fringe of minute hairs at apical margin. Clypeus with hairs about as dense as on frons, midapically with some hairs slightly curved at apical tips. Hypostomal area with straight hairs evenly distributed across most of area, 2.0–3.0 OD in length. Punctation: Head and mesosoma with punctures nearly contiguous, more or less round, and moderately impressed except as follows: labrum mostly impunctate except near fringes of hairs; clypeus with impunctate midapical truncation about length of F2 or little longer (Fig. 54); mesoscutum immediately posterior to median longitudinal sulcus with punctures separated by up to a puncture diameter; mesepisternum with punctures separated by about half a puncture diameter; metepisternum with punctures less distinct, separated by up to a puncture diameter; hypostomal area anteriorly near angle, posterior half of gena, and legs with punctures shallowly impressed, sometimes elongated into oval shape; tegula with punctures minute, sparse medially and posteriorly, separated by up to four puncture diameters (up to six puncture diameters in some specimens); pronotum, metanotum, and lateral and posterior surfaces of propodeum with punctures less distinctly impressed and background integument weakly shagreened; propodeal triangle with dorsal fourth reticulate to lineate, lower three fourths strongly shagreened, dull. T1 anterior surface moderately shagreened, weakly shining, with scattered, sparse, minute punctures throughout; T1–T3 dorsal surfaces weakly shagreened, shining, with small punctures nearly contiguous to separated by 2.0 puncture diameters on basal three-fourths, minute and much more sparsely spaced on apical fourth (4.0–6.0 puncture diameters apart), apical margins with narrow region entirely impunctate (T1 with apical impunctate margin polished, ca. 5.0–6.0, Fig. 58; weakly shagreened, ca. 2.0–5.0 puncture diameters on T2–T3); T4–T5 much more strongly shagreened throughout, with small punctures nearly contiguous to separated by 3.0 puncture diameters on basal three-fourths, minute punctures separated by 2.0–6.0 puncture diameters on apical fourth, with apical impunctate bands ca. 3.0–4.0 puncture diameters in length.
In the Nearctic, O. laticeps is known from Yukon east to Nova Scotia, and as far south as Ontario and Michigan. In the Palearctic, O. laticeps is known from Germany northwest to Sweden and Finland, east to Latvia and northern Siberian Russia (Müller 2010).
CANADA: MANITOBA, Northern Region, 12 June 1952 (1♂, Ottawa), 20 June 1930 (2♀, 1♂, Logan); NOVA SCOTIA, Kings Co., 24 May 1932, apple (1♂, Ottawa); ONTARIO, Kenora District, 10 June 1964, Viola adunca (1♀, Ottawa); Ottawa, 22 May 1973 (1♂, Ottawa); QUEBEC, AbitibiTémiscamingue Region, 24 May 1934 (1♀, Toronto); Nord-du-Québec Region, 9June 1956 (1♀, Ottawa); Bas-Saint-Laurent Region, 22 June 1916 (2♀, Ottawa); YUKON, 22 May 1951 (1♂, Ottawa), 28 May 1951 (3♂, Ottawa), 2 June 1951 (2♀, Ottawa), 12 June 1960, 3500 ft (1♂, Ottawa), 17 July 1981 (1♀, Victoria); RUSSIA: Siberia, 11–15 July (1♀, Ottawa); SWEDEN: Norrbotten Co., 6 July 1975 (1♀, Uppsala); USA: MAINE, 15 June 1982 (1♀, St. Charles); MICHIGAN, Alger Co., 3–11 June 1982, sand pit (1♀, 1♂, New York), 28 June 1982, Vaccinium myrtilloides (1♀, St. Charles); Marquette Co., 10 June 1985, Gaylussacia sp. (1♂, St. Charles), 18 June 1983 (1♀, St. Charles).