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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
Diagnosis
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).
Description: Female
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.
Structure
Labial palpus four-segmented, second labial palpal segment ca. onefourth
longer than basal most segment. Mandible with condylar ridge about twice
thickness of outer ridge, strongly converging apically (Fig. 5); apical margin with four
distinct teeth, third separated from second and fourth by carina, margin of third tooth
forming distinct V-shape with adjacent margin of second and forming weak concavity
with margin of fourth, third tooth set back from second and fourth, very slightly
directed inwards (Fig. 6); inner, ventral margin of mandible lacking distinct tooth,
strongly diverging away from condylar ridge basally; mandible apically only slightly
wider than narrowest point medially, fi rst tooth subequal to, or very slightly longer
than, second tooth, length between apical tips of second and fourth teeth 1.7 to nearly
twice wider than apical tips of fi rst and second teeth (Fig. 6). Clypeus with median
truncation at apical margin linear to weakly concave, with truncation laterally weakly
set off from remaining lateral margin of clypeus. F1 twice length of F2 or slightly more,
remaining apical fl agellar segments gradually increasing in length such that F10 about
1.2 times length of F1. Vertex behind lateral ocellus 2.5–3.0 OD in length. Genal
width 1.0 to nearly 1.5 times that of compound eye in lateral view (wider dorsally).
Preoccipital margin rounded, not carinate. Hypostomal carina moderately high, more
or less level along length of head except reduced to obsolescence at angle, sometimes
forming weak triangular projection posterior to angle. Malus forming pointed apical
spine, this spine more or less a continuation of nearby edge of vellum. Foretarsal segments
excluding basitarsal and apical-most segments with anterior lobes slightly longer
than posterior. Midtarsal segments with anterior and posterior lobes of equal width,
slightly swollen; hind tarsal segments not swollen. Hind tibial spurs slightly curved at
apical tips, outer spur about a fi fth shorter than inner. Hind basitarsal segment with
lateral margins of outer surface parallel along most of length, converging apically.
Distribution
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).
Material Examined
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).
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