A review of the non-metallic Osmia (Melanosmia) found in North America, with additional notes on palearctic Melanosmia (Hymenoptera, Megachilidae)

Abstract We review the six species of non-metallic Osmia (Melanosmia) found in North America, including the description of two new species found in Canada and the northern United States: Osmia (Melanosmia) aquilonaria sp. n., and Osmia (Melanosmia) nearctica sp. n., respectively belonging to the inermis and xanthomelana species groups. We additionally provide keys to the non-metallic Melanosmia found in North America, and update keys to the palearctic Melanosmia based on study of the type specimens of Osmia disjuncta Tkalců, Osmia ephippiata Smith, Osmia ishikawai Hirashima, and Osmia pamirensis Gussakovskij.


Introduction
Th is is a treatment of the members of the subgenus Melanosmia (sensu Michener 2007) that lack any metallic blue or green coloration on the integument of the mesosoma and metasoma (the head also usually lacks metallic blue or green coloration, although there is a hint of such color in the head of some males). For this reason, some workers informally refer to such species as the "dark Osmia." As treated herein, the group roughly corresponds to Melanosmia s. str. as used by Sandhouse (1939), excluding O. bucephala Cresson (1864), which we have excluded based on the slight metallic blue sheen found throughout the body of this species. It is currently unknown if the "dark Osmia" as a group has any phylogenetic standing; our decision to assemble and give taxonomic treatment to these species is based solely on the ease of distinguishing its members. In addition, certain species in this group are distributed in both the Eastern and Western Hemispheres, without, as far as we know, having been introduced by human activity. Other holarctic species of Osmia are rare and known to be human introductions. With few exceptions, most non-metallic Melanosmia are distributed in northern temperate to borealalpine regions, which possibly facilitated the widespread distribution of some species via Beringia.
As currently understood, the "dark Osmia" group found in North America is comprised of four holarctic species plus two new species apparently restricted to North America, for a total of six species. In addition, some (but not all) females of Osmia (Melanosmia) tersula Cockerell (1912) mostly lack a metallic blue or green sheen to their integument, and are therefore included in the key to non-metallic Melanosmia below.
Given the holarctic distribution of many non-metallic Melanosmia, there is a possibility that the two new North American species described herein are already known from the Palearctic. In order to avoid producing new junior synonyms, it is necessary to understand the 20 species of Melanosmia known from the Palearctic (Ungricht et al. 2008; (Table 1). Unfortunately, not all species are well described in the literature and the two species described by Wu (O. nigroscopula Wu 1982 andO. jilinensis Wu 2004) are unknown to us although we attempted to borrow the holotype material.
Of the remaining 18 species of palearctic Melanosmia, three species (O. alticola Benoist 1922, O. maritima Friese 1885, and O. xanthomelana Kirby 1802 were placed in the xanthomelana species group by Tkalců (1983) due to the shared swollen gonoforceps of the males and the shining propodeal triangle (metapostnotum) of the females. Tkalců (1983) recognized a second group of palearctic Melanosmia, the inermis species group, whose members have relatively thin gonoforceps in males and dull posterior surface of the propodeum and propodeal triangle in females. Th e species that have been explicitly placed in the inermis species group (Tkalců 1983;Müller 2002 steinmanni Müller 2002;O. svenssoni Tkalců 1983;and O. uncinata Gerstäcker 1869. Osmia disjuncta Tkalců 1995, was originally described as closely related to O. parietina and O. laticeps (as O. hyperborea), and upon examination of the female holotype we conclude that it also belongs to the inermis species group.  (Kirby) xanthomelana non-metallic ♀ specimen compared with syntypes by TG; ♀, ♂ non-type specimens  segregated O. nigriventris (Zetterstedt 1838) into a third species group; this classifi cation scheme highlights some unusual characteristics of O. nigriventris (e.g., the extremely swollen clypeal margin of the female and laterally refl exed posterior terga of the male). Th ese unusual features are shared with the North American species O. bucephala, a species that has further apomorphies that have obscured its taxonomic placement within Osmia.
Th e remaining species of palearctic Melanosmia have received less treatment in recent revisions and are thus considerably less well-known. Th ey are O. ephippiata Smith 1879, O. ishikawai Hirashima 1973, O. melanota Morawitz 1888, O. pamirensis Gussakovskij 1930, O. recta Pérez 1902, and O. thoracica Radoszkowski 1874. Of these, we were able to exclude O. melanota from consideration as a possible component of the North American fauna due to the original description of the type material as dark metallic blue (Morawitz 1888, p. 243, 244). Osmia recta can also be excluded due to the fact that Pérez (1902, p. 63) described the holotype male as having two submedial tufts of long, blackish-grey hairs on T3 and T4; in addition, the species' known distribution is in Algeria, quite unlike the more northern distribution of the known holarctic species.
Of the palearctic Melanosmia not treated by Tkalců (1983Tkalců ( , 1995 or Müller (2002), we have seen the holotype specimens of O. ephippiata and O. ishikawai. We have also examined a female syntype of O. pamirensis, and one of us (TG) has additionally seen the type series of two males and nine females of O. pamirensis at the Russian Academy, St. Petersburg in 1984 (although, according to notes made by TG at the time of his visit, the males of the type series appear not to be conspecifi c). Tkalců (1983) did not treat females of O. laticeps (as O. hyperborea) in his revision of palearctic Melanosmia; the female of this species was diagnosed by Haeseler (1999). Herein we give further description of the female of O. laticeps and include it in an updated key to palearctic Melanosmia based on Tkalců (1983Tkalců ( , 1995 and Müller (2002).

Materials and methods
Th e morphological terminology used herein follows that proposed by Michener (2007), with the exception of the following terms: fl agellar segment instead of fl agellomere, and basitarsal segment instead of basitarsus; in addition, we follow sculpture and punctation terminology proposed by Harris (1979). Mandibular teeth are numbered from ventral-most tooth to dorsal-most tooth. Th us, the ventral-most tooth is the fi rst tooth and the next ventral-most tooth is the second. In the species treated herein, between the second and dorsal-most tooth is a smaller, slightly more inset, cutting edge extending from the dorsal-most tooth, here called the third tooth. Th e dorsal-most tooth is the fourth tooth.
Th e following morphological abbreviations are used: fl agellar segment (F), metasomal tergum (T), metasomal sternum (S), and ocellar diameter (OD). Measurements are given for the holotype specimen, with the observed range from other specimens following in parentheses.

Key to North American Males of Non-Metallic Osmia (Melanosmia)
[Modifi ed from Tkalců 1983Tkalců , 1995and Müller 2002] 1. T5 and T6 with apicolateral angles strongly refl exed laterally (Fig. 53)  Vertex of head in frontal view relatively strongly ascending, with outline of head thus more quadrangular; T2-T4 with marginal zone weakly impressed, densely shagreened at least on basal half; T2-T4 with hairs bright yellowbrown; S3 with midapical emargination one-fi fth as deep as broad; S6 with midapical truncation more than one-half as long as broad; gonoforceps with outer margin preapically distinctly widened, broader than basally on gonoforceps (Fig. 69)  Vertex of head in frontal view relatively weakly ascending, with outline of head thus rounder; T2-T4 with marginal zone strongly impressed on its whole width, polished to superfi cially shagreened; T2-T4 with hairs yellowish-white; S3 with midapical emargination one-third as deep as broad; S6 with midapical truncation less than one-half as long as broad; gonoforceps with outer margin preapically not widened, about as broad at this point as basally on gonoforceps (Fig. 66)  Description. Female. Figs 1, 2, 13-18. Total length: 8.2-11.0 mm; forewing length: 6.4-6.8 mm; length of lateral ocellus to preoccipital margin 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 strongly infuscate along leading edge of forewing, especially along dorsal half of marginal cell.
Pubescence: Clypeus below apical margin with lateral tuft of golden, medially directed hairs. Dark brown, minutely branched hairs on most of body except as follows: pale golden to white, minutely branched hairs interspersed with brown on interantennal area, vertex, posterior surface of propodeum excluding triangle, and dorsal surfaces of T1, T2, T6; almost entirely pale golden to white, minutely branched hairs on mesoscutum, mesoscutellum, and metanotum; dark-brown, simple hairs interspersed with minutely branched hairs on most of body, except simple hairs lacking on dorsal mesosoma; dark-brown, simple hairs only (no branched hairs) on all tarsi and scopa; brown, short, simple hairs evenly covering forewing. Galea and basal two labial palpal segments with hairs on lateral margins straight, 0.2-0.5 OD in length. Labrum with long hairs arranged in two curved, transverse rows, along subapical margin and approximately at midpoint, with additional fringe of shorter hairs at apical margin. Clypeus with hairs about as dense as on frons. Hypostomal area with hairs evenly distributed across area, straight to slightly wavy at apical tips, 2.5-4.0 OD in length. Punctation: Head and mesosoma with punctures nearly contiguous, more or less round, and moderately impressed except as follows: labrum mostly impunctate; clypeus with impunctate midapical truncation about length of F2 or little longer (Fig. 15); mesoscutum immediately posterior to median longitudinal sulcus with punctures separated by up to two puncture diameters; mesepisternum with punctures separated by about half a puncture diameter; hypostomal area, pronotum, and legs with punctures shallowly impressed, sometimes elongated into oval shape; tegula with punctures minute, sparse medially and posteriorly, separated by up to four or fi ve puncture diameters; metepisternum, metanotum, and lateral and posterior surfaces of propodeum with punctures very weakly impressed, with background integument strongly granulose, dull; propodeal triangle with dorsal fourth fi nely areolate to lineate, lower three fourths strongly granulose, dull (Fig. 16). T1 anterior and dorsal surfaces, and T2-T5 strongly shagreened, dull, with small, sparse punctures throughout except for apical margins, these punctures with integument anterior to them slightly raised, papillate; T1-T5 apical impunctate bands with length at midpoint about 4.0-6.0 puncture diameters or little more (Figs 17, 18).
Structure: Labial palpus four-segmented, second labial palpal segment ca. onethird longer than basal-most segment. Mandible with outer and condylar ridges of subequal thickness, parallel along length to very weakly converging apically (Fig. 1); apical margin with four strongly pointed teeth, third separated from second and one-fourth to one-fi fth from apical margin one-third from apical margin Fig. 22; one-third to onefourth from apical margin (shorter and broader than in O. svenssoni) fourth by carina, margin of third tooth forming distinct V-shape with adjacent margin of second and slightly smaller V-shape with adjacent margin of fourth, third tooth set back from second and fourth, very slightly directed inwards (Fig. 2); inner, ventral margin of mandible lacking distinct tooth, slightly diverging away from condylar ridge basally; mandible apically widened (1.3 times wider than median width), fi rst tooth slightly longer than other teeth, length between apical tips of second and fourth teeth slightly wider than (ca. 1.2 times) apical tips of fi rst and second teeth (Fig. 2). Clypeus with apical margin linear to moderately emarginate medially, with entire apical truncation laterally more or less contiguous with remaining lateral margin of clypeus (not forming 90 degree angle with lateral apical margin of clypeus; Fig. 15). F1 twice length of F2 or slightly more, remaining apical fl agellar segments gradually increasing in length such that F10 subequal to F1 or little longer. Vertex behind lateral ocellus 2.5-3.0 OD in length. Genal width 1.5 to nearly 2.0 times that of compound eye in lateral view. Preoccipital margin rounded, not carinate. Hypostomal carina moderately high, highest at about midpoint of hypostomal area posterior to angle and sometimes forming moderate triangular projection at this point, tapering to low carina or near obsolescence at 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 strongly curved at apical tips, outer spur about one fi fth shorter than inner. Hind basitarsal segment with lateral margins of outer surface parallel.
Color: Black to dark brown, sometimes with reddish overtones especially on mouthparts, labrum, mandible, fl agellar segments, legs, and apical margins of T1-T6 and S1-S3. Wings mostly clear except weakly infuscate along leading edge of forewing, especially along dorsal half of marginal cell.
Pubescence: White to golden, minutely branched hairs on body except golden to pale golden, stouter hairs on inner surfaces of tarsi, S4, and S6. Labrum covered with hairs on apical third and with hairs forming short fringe at apical margin. S2 with hairs at apical third relatively long (ca. 3.0 OD). S3 with dense, medially directed hairs fi lling entire emargination (hairs ca. 1.0 OD in length medially, nearly 2.0 OD laterally) (Fig. 24). S4 midapical truncation with two patches of dense, golden, distally hooked hairs, these patches of hairs medially interrupted by nearly 1.0 OD, with hairs distally meeting at midpoint, each patch along apical margin with hairs oriented horizontally and on premarginal area directed increasingly vertically (Figs 24, 25). S6 midapical truncation sparsely covered with short, distally hooked hairs arising from papillate bases (Fig. 28).
Punctation: Head with punctures ovate to nearly circular, separated by one-fourth to one-half puncture diameter and deeply impressed except as follows: labrum mostly impunctate on basal two-thirds; clypeus with impunctate band along apical margin, about one-third length of F1 in length; disc of clypeus, interantennal area, and paraocular area with punctures small, ovate, and nearly contiguous (punctures mostly obscured beneath dense hairs); hypostomal area anteriorly near angle with punctures weakly, shallowly impressed. Mesosoma with punctures more or less round, nearly contiguous to separated by up to a half puncture diameter, deeply impressed except as follows: mesoscutum immediately posterior to median longitudinal sulcus with punc-tures separated by up to one, sometimes as much as three puncture diameters; tegula with punctures minute, sparse medially, separated by up to eight to ten puncture diameters; pronotum, metepisternum and lateral and posterior surface of propodeum strongly shagreened, with weakly, shallowly impressed, larger punctures; metanotum and propodeal triangle strongly granulose, dull (Fig. 21); propodeal triangle lineolate on dorsal fi fth; legs with inner surfaces of trochanters, femora, and tibiae shining, with scattered smaller punctures. T1 with anterior surface strongly shagreened, dull; metasomal terga with dorsal surfaces excluding apical margins strongly shagreened, apical impunctate margins moderately to weakly shagreened (except T7 moderately polished). T1 dorsal surface with punctures minute, moderately distinct and wellimpressed, separated from 1.0 to 3.0 puncture diameters; apical impunctate margin medially ca. 10.0 puncture diameters in length, laterally as little as 6.0 puncture diameters. T2-T7 with punctures minute, T2 with punctures separated by ca. 1.0 puncture diameter medially (sparser towards impunctate apical margin on all terga), successively posterior terga with punctures progressively becoming more widely spaced to about 3.0 puncture diameters apart on disc of T7; T2-T6 with apical impunctate margins 6.0-9.0 puncture diameters in length, T7 with apical impunctate margin 4.0-6.0 puncture diameters in length. S1-S3 with punctures weakly, shallowly impressed. S4 with integument granular, dull (Fig. 24). S5-S6 lacking distinct punctures, weakly shagreened.
Structure: Mandible with outer and condylar ridges converging apically; apical margin with two teeth, upper tooth distinctly shorter and slightly wider than lower, upper tooth with inner and dorsal margins forming ca. 70-80 degree angle; inner, ventral margin of mandible weakly diverging away from condylar ridge basally. Clypeus apical margin with irregular tubercles, lacking distinct apical truncation. Flagellar segments subequal in length, except F1 about three-fourths length of F2 and F11 slightly longer than other segments. Vertex behind lateral ocellus 2.0 OD in length or nearly so. Genal width subequal that of compound eye in lateral view (slightly wider dorsally). Preoccipital margin rounded, not carinate. Hypostomal carina moderately high, gradually tapering to near obsolescence at angle, not forming distinct tooth. Malus forming small but distinct apical spine. Foretarsal segments excluding basitarsal and apical-most segments with lobes slightly, equally swollen. Mid-and hind tarsal segments not swollen. Hind tibial spurs curved at apical fi fth, outer spur slightly shorter than inner. Hind basitarsal segment with lateral margins of outer surface weakly diverging apically, with strong tooth on inner margin (Fig. 22). T6 midapically with small but usually distinct emargination, forming ca. one-fourth to one-half of circle in outline (Fig. 23); T6 lateroapical margin smoothly, weakly convex, not forming distinct tooth. T7 midapically strongly emarginate, forming semicircle about as wide as deep (ca. 0.5-0.8 OD wide), with spines on either side of emargination weakly pointed, basally nearly as wide as emargination width (Fig. 23). S2 evenly convex, covering most of S3. S3 with midapical emargination relatively wide and shallow (half entire width of sternum, 1.0 OD in length, measuring only apical margin of sternum and not including basal fringe of hairs; Fig. 24). S4 midapically with wide truncation (about half width of entire sternum), medially with shallow but distinct emargination between lateral tufts of hairs (Fig. 24). S5 with apical margin evenly, strongly concave along median half of margin. S6 with strong midapical truncation, slightly less than one-third width of sternum, truncation slightly wider than deep, apical margin of truncation weakly, evenly rounded apically, sometimes with small emargination medially (Fig. 28). S8 as in Fig. 29. Gonoforceps weakly narrowed apical to subapical bend in dorsal, ventral, and lateral views (Figs 26,27,(30)(31)(32)  Etymology. Th e name "aquilonaria" is Latin, meaning northern or northerly, and is in reference to the northern distribution of the species in North America. Figs 3,4,52,56,60 Anthophora (Osmia)  Diagnosis. Females are known by the slightly acute angle or tooth midway on the ventral margin of the mandible (Fig. 52). Males can be distinguished by the form of the S4, which is strongly truncate and emarginate medially, forming distinct, rounded sublateral lobes (Fig. 60).   Figs 5,6,54,58 (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.

Osmia (Melanosmia) laticeps Th omson
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).
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 punc- tures 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 .
Comments. We have not found any male specimens of O. maritima in the material of nearctic Osmia available to us. It is possible that once male specimens are discovered they may prove to be a distinct species from their palearctic relatives (if, as in O. aquilonaria, the novel diagnostic characters of the species are only found in the males); however, since a holarctic distribution is well established for other Osmia species (e.g., O. inermis and O. nigriventris), until proven otherwise we conservatively retain the name O. maritima for this species. Interestingly, there appear to be two female morphs of O. maritima. Specimens from Alaska and the Russian Far East share pale hair on the paraocular area and mesepisternum and scarcely sculptured apical areas on T2 and T3; females from the Northwest Territories and western Europe have dark hair on the paraocular area and mesepisternum and microsculptured apical areas of T2 and T3. Osmia maritima from the Palearctic is known to be polylectic and nests in sandy soil with cells composed of chewed leaves and sand grains (Müller 2010 and references therein).
Material examined. CANADA: NORTHWEST TERRITORIES, Inuvik Region, 17 June 1971 (1♀, Ottawa), 20-25 June 1971(3♀, Ottawa), 28-30 June 1971(1♀, Ottawa), 11 July 1948 In the Palearctic, O. nearctica is most similar to O. xanthomelana, but can be differentiated from that species by the following characters: In females, the propodeal triangle is shining but weakly shagreened throughout (Fig. 36) (O. xanthomelana with entirely polished, strongly shining lower half of the propodeal triangle), the outer hind tibial spur is only about half the length of the hind basitarsal segment (O. xanthomelana with outer hind tibial spur nearly three-fourths length of hind basitarsal segment), and the lower margin of the mandible has a distinct, translucent fl ange that curves away from the condylar ridge (O. xanthomelana with the lower margin of the mandible opaque, forming a ridge that is parallel to the condylar ridge). Th e hairs of the mesepisternum tend to be dark brown in O. nearctica, while in O. xanthomelana the hairs tend to be pale yellow to white, and the hairs of the hypostomal area tend to be denser in O. nearctica than in O. xanthomelana.
In males, the propodeal triangle is weakly shagreened throughout in O. nearctica (Fig. 41) (O. xanthomelana with entirely polished, strongly shining lower half of the propodeal triangle); the lower tooth of the mandible is only slightly longer than the upper tooth in O. nearctica (in O. xanthomelana the lower tooth of the mandible is much longer than the upper tooth and the entire apical margin of the mandible is conspicuously wider than the middle, approaching the look of male Acanthosmioides); T7 midapically has a shallower emargination in O. nearctica (Fig. 43)  Description. Female. Figs 9, 10, 33-38. Total length: 9.0-11.5 mm; forewing length: 6.5-7.2 mm; length of lateral ocellus to preoccipital margin 0.6 mm; length of lateral ocellus to compound eye 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 moderately infuscate, more strongly infuscate in marginal cell and distal to cells.
Pubescence: Clypeus below apical margin with lateral tuft of golden, medioposteriorly directed hairs. Brown, minutely branched hairs on most of body except as follows: white to yellow, minutely branched hairs interspersed with brown on outer surface of mandible, face excluding ventral third of clypeus and sometimes on vertex (and gena), and dorsal surfaces of T2, T5, T6; almost entirely white to yellow, minutely branched hairs on vertex (sometimes), mesoscutum, mesoscutellum, metanotum, dorsally on propodeum (excluding triangle), pronotal lobe, and dorsal surface of T1; brown, simple hairs interspersed with minutely branched hairs on most of body, except simple hairs lacking on dorsal mesosoma; simple hairs only (no branched hairs), golden on all tarsi and brown on scopa; brown, short, simple hairs evenly covering forewing. Galea and basal two labial palpal segments with hairs on lateral margins straight, 0.2-0.5 OD in length. Labrum with long hairs arranged in two curved, transverse rows, along subapical margin and approximately at midpoint, with additional fringe of shorter hairs at apical margin. Clypeus with hairs about as dense as on frons. Hypostomal area with hairs densely distributed across area, straight to weakly incurved at apical tips, 3.0-4.0 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. 35); mesoscutum posterior to median longitudinal sulcus with punctures separated by up to a puncture diameter; mesepisternum with punctures less strongly impressed, nearly contiguous to separated by about half a puncture diameter; hypostomal area near angle and legs with punctures shallowly impressed, sometimes elongated into oval shape; tegula with punctures minute, sparser medially and posteriorly, separated by up to three or four puncture diameters; pronotum, metepisternum, metanotum, and lateral and posterior surfaces of propodeum with punctures very weakly impressed, with background integument weakly shagreened; propodeal triangle with dorsal fourth reticulate, lower three fourths shagreened, weakly shining (Fig. 36). T1 anterior surface weakly shagreened, shining, with scattered punctures at dorsolateral angle; T1-T3 dorsal surfaces very weakly shagreened, shining, excluding apical impunctate margins with small punctures nearly contiguous to separated by 1.0 puncture diameter (on T1, Fig. 37) to separated between 1.0 to 3.0 puncture diameters (on T3); apical impunctate bands 2.0-4.0 puncture diameters in length. T4-T5 dorsal surfaces shagreened, weakly shining, excluding apical impunctate bands with punctures nearly contiguous to separated by 2.0 puncture diameters; apical impunctate bands about 5.0-8.0 puncture diameters in length. T6 with punctures minute, nearly contiguous, mostly obscured beneath dense hairs.
Structure: Labial palpus four-segmented, second labial palpal segment subequal to or ca. one-fourth longer than basal-most segment. Mandible with outer and condylar ridges of subequal thickness, parallel along length (Fig. 9); apical margin with four well-developed teeth, lacking carina separating third tooth from second and fourth, margin of third tooth forming distinct V-shape with adjacent margin of second and slightly smaller V-shape with adjacent margin of fourth, third tooth more or less on same plane as second and fourth (Fig 10); inner, ventral margin of mandible lacking distinct tooth, diverging away from condylar ridge basally; mandible apically widened (ca. 1.7 times wider than median width), fi rst tooth longer than other teeth, length between apical tips of second and fourth teeth subequal to slightly wider than apical tips of fi rst and second teeth (Fig. 10). Clypeus apical margin with distinct truncation on middle half, this truncation with lateral corner slightly produced, forming weak protuberance relative to apical margin of truncation and forming ca. 90 degree angle with apical margin of clypeus lateral to truncation (Fig. 35). F1 twice length of F2, remaining apical fl agellar segments gradually increasing in length such that F10 subequal to F1 or little longer. Vertex behind lateral ocellus 2.0-2.5 OD in length. Genal width 1.5 to nearly 2.0 times that of compound eye in lateral view. Preoccipital margin rounded, not carinate. Hypostomal carina moderately high, highest at about midpoint of hypostomal area posterior to angle and forming distinct triangular projection at this point, tapering to low carina or near obsolescence at angle. Malus forming pointed apical spine. Foretarsal and midtarsal segments excluding basitarsal and apical-most segments with anterior lobes slightly longer than posterior; hind tarsal segments not swollen. Hind tibial spurs weakly curved, outer spur about a fi fth shorter than inner. Hind basitarsal segment with lateral margins of outer surface parallel.
Color: Black to dark brown, sometimes with reddish overtones especially on mouthparts, labrum, mandible, fl agellar segments, legs, and apical margins of T1-T6 and S1-S3. Wings mostly clear except weakly infuscate along leading edge of forewing, especially along dorsal half of marginal cell.
Pubescence: White to pale golden, minutely branched hairs on body except golden to pale golden, stouter, simple hairs on inner surfaces of tarsi, S4, and S6, and intermixed with white, branched hairs on mandible, lower gena, and outer surfaces of tarsi. Labrum with row of hairs across approximate midline, sparsely covered with hairs on apical fourth and with hairs forming short fringe at apical margin. S2 with hairs at apical third ca. 1.5 to 2.0 OD in length. S3 with medially directed hairs fi lling entire emargination (hairs ca. 1.0 OD in length medially, 2.0 OD laterally) (Fig. 44). S4 with weakly defi ned, asetose longitudinal strip, otherwise covered with regularly spaced, simple, short, weakly distally hooked, golden hairs arising from papillate bases (Fig.  44). S6 midapical truncation with very sparse, short, simple hairs arising from papillate bases (Fig. 47).
Punctation: Head with punctures ovate to nearly circular, separated by one-fourth to one-half puncture diameter (up to 1.0 puncture diameter posterior to compound eye) and deeply impressed except as follows: labrum mostly impunctate on basal twothirds; clypeus with impunctate band along apical margin, about one-fourth length of F1; disc of clypeus, interantennal area, and paraocular area with punctures small, ovate, and nearly contiguous (punctures mostly obscured beneath dense hairs); hypostomal area anteriorly near angle with punctures weakly, shallowly impressed. Mesosoma with punctures more or less round, nearly contiguous to separated by up to a half puncture diameter, deeply impressed except as follows: mesoscutum immediately posterior to median longitudinal sulcus with punctures separated by up to one, sometimes as much as two puncture diameters; tegula with punctures minute, sparse medially, separated by up to fi ve puncture diameters; pronotum, dorsal half of metepisternum and lateral and posterior surface of propodeum weakly shagreened, with moderately impressed, larger punctures; ventral half of metepisternum mostly impunctate, weakly shining; propodeal triangle lineolate to reticulate on dorsal third, shagreened and weakly shining on ventral two-thirds; legs with inner surfaces of femora and tibiae shining, with scattered smaller punctures. T1 with anterior surface very weakly shagreened, shining; T1-T2 with dorsal surfaces excluding apical margins weakly shagreened, shining; T3, T6-T7 dorsal surfaces moderately shagreened; T4-T5 dorsal surfaces strongly shagreened, dull; metasomal terga with apical impunctate margins polished. T1 dorsal surface with punctures minute, distinct and well-impressed, nearly contiguous to separated by a puncture diameter; apical impunctate margin ca. 4.0-5.0 puncture diameters in length (sometimes medially as long as 6.0-7.0 puncture diameters in length). T2-T7 with punctures minute, T2 with punctures separated by ca. 1.0 puncture diameter medially, successively posterior terga with punctures progressively becoming more widely spaced to about 3.0 puncture diameters apart on disc of T6; T2-T6 with apical impunctate margins 4.0-8.0 puncture diameters in length, T7 lacking apical impunctate margin. S1-3 with punctures minute, well-impressed, nearly contiguous to separated by ca. 1.0 puncture diameter. S4-S6 lacking distinct punctures, weakly shagreened.
Structure: Mandible with outer and condylar ridges converging apically; apical margin with two teeth, upper tooth distinctly shorter and wider than lower; inner, ventral margin of mandible very weakly diverging away from condylar ridge basally. Clypeus apical margin mostly linear except with weak irregular tubercles above tufts of setae below apical margin at each side. Flagellar segments subequal in length, except F1 slightly shorter than F2 and F11 slightly longer than F10. Vertex behind lateral ocellus 1.5-2.0 OD in length. Genal width in lateral view ventrally subequal to, dorsally ca. 1.3 times wider than, width of compound eye. Preoccipital margin rounded, not carinate. Hypostomal carina relatively short, gradually tapering to near obsolescence at angle, not forming distinct tooth. Malus forming distinct apical spine. Foretarsal segments excluding basitarsal and apical-most segments with anterior lobes slightly more swollen than posterior. Mid-and hind tarsal segments not swollen. Midfemur with swollen projection on ventral surface. Hind tibial spurs weakly curved at apical sixth, outer spur ca. one-fi fth shorter than inner. Hind basitarsal segment widening about a third from apical margin, with strong tooth on inner margin at widest point (Fig. 42). T6 midapically with wide, shallow emargination, forming ca. one-fourth of circle in outline (Fig. 43); T6 lateroapical margin slightly concave sublaterally, forming weak lobe. T7 midapically strongly emarginate, forming semicircle about as wide as, or slightly wider than, deep (ca. 1.5 OD wide; Fig. 43), with spines