Osmia Melanosmia laticeps Thomson

Rightmyer, Molly G., Griswold, Terry & Arduser, Michael S., 2010, A review of the non-metallic Osmia (Melanosmia) found in North America, with additional notes on palearctic Melanosmia (Hymenoptera, Megachilidae), ZooKeys 60, pp. 37-77 : 49-52

Osmia Melanosmia laticeps Thomson Figs 5, 65458, 61

Osmia laticeps Thomson 1872: 242 [Lectotype female: Lund]; Dalla Torre 1896: 414 [synonymy with Osmia uncinata Gerstäcker]; Tkalců 1983: 154 [Lectotype designation]; Nilsson 2009: 51 [rejection of synonymy with Osmia uncinata Gerstäcker].

Osmia (Melanosmia) hyperborea Tkalců 1983: 156 [Holotype male: Uppsala]; Schwarz et al. 1996: 126 [synonymy with Osmia parietina Curtis]; Haeseler 1999: 454 [rejection of synonymy with Osmia parietina Curtis, diagnosis of female]; Nilsson 2009: 52 [synonymy with Osmia laticeps Thomson].

Diagnosis.

Females of Osmia 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, Osmia laticeps is most similar to Osmia 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 first noticed by Haeseler 1999): in Osmia 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 Osmia 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. The malus of the foretibia has the apical tip evenly tapering to a point in Osmia laticeps , while in Osmia uncinata the tip is slightly more blunt. The outer hind tibial spur is more strongly downcurved in Osmia uncinata than in Osmia laticeps . Additionally, the hairs of the hypostomal area are denser and more strongly incurved in Osmia laticeps than in Osmia 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 inflection), and the relatively unmodified S4 (Fig. 61): the apical margin of S4 is evenly convex and midapically on S4 the relatively short, unmodified 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, flagellar 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 pun ctures 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. one-fourth 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, first 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 first 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 flagellar 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 fifth shorter than inner. Hind basitarsal segment with lateral margins of outer surface parallel along most of length, converging apically.

Distribution.

In the Nearctic, Osmia laticeps is known from Yukon east to Nova Scotia, and as far south as Ontario and Michigan. In the Palearctic, Osmia laticeps is known from Germany northwest to Sweden and Finland, east to Latvia and northern Siberian Russia ( Müller 2010).

Comments.

Osmia laticeps is oligoletic on Vaccinium ( Ericaceae ) ( Nilsson 2009).

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, Abitibi-Témiscamingue Region, 24 May 1934 (1♀, Toronto); Nord-du-Québec Region, 9 June 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).