Extracted from: Sheffield C. S., et al (2011). Leaf cutter and Mason Bees of the Genus Megachile Latreille (Hymenoptera; Megachilidae) in Canada and Alaska. Canadian Journal of Arthropod Identification No. 18 |
Megachile (Megachile) lapponica Thomson, 1872
Megachile lapponica Thomson, 1872. Hym. Scand. 2: 227.
Megachile nivalis Friese, 1903. Ztschr. System. Hym. Dipt. 3: 246. (♀). New Synonymy
Megachile melanopyga amaguella Cockerell, 1924. Ann. Mag. Nat. Hist. (9) 13: 602 (♂).
Megachile lapponica baicalica Cockerell, 1928. Ann. Mag. Nat. Hist. (10) 1: 355 (♀) (preoccupied).
Megachile lapponica var kurbati Cockerell, 1928. Ann. Mag. Nat. Hist. (10) 1: 356 (♀).
Megachile lapponica fuscifrons Cockerell, 1930 . Entomol. 63: 184 (Nom. nov. Megachile lapponica baicalica Cockerell, 1928).
Megachile (Anthemois) santiamensis Mitchell, 1934. Trans. Amer. Entomol. Soc. 59: 311. (♀). New Synonymy
Megachile lapponica ishikawai Hirashima and Maeta, 1974. Kontyu 42: 170 (♀).
Diagnosis. The female of M. lapponica can be recognized by the combination of 5-dentate mandibles, and T6 with scopa black. They are most similar to M. centuncularis and M. relativa. The females of these species have entirely pale scopa. The male of M. lapponica can be recognized by the combination of simple and dark front tarsi, front coxa without spine, 3-dentate mandibles with the teeth equally spaced, clypeus with a prominent median tubercle on apical margin, the inner and outer tarsal claws that are equally sharp, the first submarginal cell with vein r shorter than vein Rs of the second submarginal cell, more prominent hypostomal tubercle and a deep, well defined hypostomal concavity. They are most similar to M. centuncularis, M. inermis and M. relativa. Males of M. centuncularis lack a median tubercle on the clypeus, and have the outer tarsal claw much more rounded than the inner claw. Males of M. inermis have 3-dentate mandibles with the 2nd tooth much closer to the apical tooth than the inner tooth. Males of M. relativa have the first submarginal cell with vein r subequal to vein Rs of the second submarginal cell, and a less prominent hypostomal tubercle and a more shallow, less defined hypostomal concavity.
FEMALE: Length 9-12 mm.
Head. 1) compound eyes very slightly convergent below; lateral ocelli nearer margin of vertex than eyes (4:5), 2) clypeal margin nearly straight, obscurely crenulate and slightly emarginated medially, 3) mandibles 5-dentate, with an incomplete cutting edge between 2nd and 3rd teeth (Plate 1, Figure M16), 4) gena slightly broader than compound eye (7:9), 5) punctures on vertex rather fine and shallow, to some degree separated, but rather irregular, becoming slightly more coarse and close on gena, frons more rugosopunctate, supraclypeal area rugosopunctate laterally but with shining interspaces medially, clypeus with rather shallow but quite close punctures, 6) pubescence whitish, more or less erect and copious around antennae and on gena though hardly obscuring surface; clypeus with pale hairs more yellowish, vertex and area surrounding ocelli, and upper gena adjacent to eye margin with erect but rather sparse black pubescence, 7) F1 longer than broad (2:1), twice as long as pedicel, and longer than remaining flagellomeres, which are slightly longer than broad (2:1.7), apical flagellomere more elongate, about twice as long as broad.
Mesosoma. 1) pubescence whitish and rather copious on laterally and posteriorly, and on upper segments of legs, becoming yellow on apical segments, the mesoscutum and scutellum with erect but rather thin and sparse, black pubescence, 2) mesoscutum shining medially, the punctures quite shallow and rather coarse, with distinct interspaces, becoming densely crowded laterally and anteriorly, those on scutellum and axilla somewhat finer and very close, slightly separated on scutellum medially; pleura somewhat shining below, punctures shallow and rather coarse, slightly separated, becoming closely crowded above where the surface is dull; propodeum smooth and somewhat shining, punctures fine and evenly spaced, triangle shiny and impunctate, 3) mid and hind basitarsi slightly shorter and narrower than tibiae, spurs yellow, 4) tegula very finely and obscurely punctate anteriorly, shiny and with shallow and sparse punctures in posterior half, 5) wings subhyaline, veins black.
Metasoma. 1) T2-T4 with shallow, subbasal grooves, their basal margins faintly carinate, apical margins depressed laterally but not medially, these lateral areas quite densely whitish fasciate; discal pubescence erect and black on T3-T5, apically on T2, more copious, elongate and entirely white on T1; punctures of T1 fine, well separated but not sparse, somewhat coarser and irregular on the more apical terga, T5 with a shallow, subbasal groove laterally with basal margin faintly carinate, apical margin of T5 depressed and whitish fasciate across entire width, T6 straight in profile, with a few, robust, erect, but rather short dark hairs evident, 2) S6, and S5, at least apically, sparsely covered with black scopal hairs and with an apical fringe of very short dark hairs; scopa otherwise yellow; the sterna closely, deeply and rather finely punctate basally, punctures becoming somewhat more sparse apically, apical margin of each sternum very narrowly yellowish-hyaline.
MALE: Length 9-12 mm.
Head. 1) compound eyes slightly convergent below; distance between lateral ocelli and vertex subequal to distance to eyes, 2) clypeal margin nearly straight on either side of a distinct but small median tubercle, 3) mandible 3-dentate, lower process rather narrow, subtruncate apically, subbasal in position, 4) gena broader than compound eye (4:3), 5) punctures fine, slightly separated across vertex posteriorly, sparse between lateral ocelli and eye, becoming close on gena above and densely crowded or rugosopunctate below; face below ocelli rather coarsely rugosopunctate, becoming finely so below antennae and on clypeus; hypostomal depression well defined, hypostomal tubercle long and relatively prominent, broadly interrupting hypostomal carina, 6) pubescence golden, becoming paler on lower part of gena, quite long and copious around antenna and lower part of face, on gena below, vertex with an admixture of pale and black pubescence, 7) F1 longer than broad (2.5:2), longer than pedicel, slightly shorter than remaining flagellomeres, which are longer than broad (3:2), apical flagellomere more elongate, twice as long as broad.
Mesosoma. 1) pubescence golden, becoming paler and quite long and copious laterally and posteriorly, mesoscutum and scutellum with more or less intermixed light and dark hairs that are quite long and erect but sparse, 2) mesoscutum dull, punctures close, shallow, not very coarse, slightly separated only in centre of disc; punctures of scutellum slightly separated along mid-line, but otherwise quite uniformly close, those on axilla much finer and densely crowded; pleura dull, punctures shallow, quite close and poorly-defined; propodeum relatively smooth and shining, with the fine punctures evenly spaced, triangle shiny and impunctate, 3) basitarsi quite short and slender; mid tibial spur short but well developed, 4) tegula brownish, shining, rather uniformly, minutely and rather closely punctate, 5) wings subhyaline, veins brown, vein r of first submarginal cell shorter than vein Rs of second submarginal cell.
Metasoma. 1) T2-T4 shallowly grooved or depressed across base, basal margin of grooves not distinctly carinate, apical margins depressed only toward sides, depressed medially only on T4 and T5, pale apical fasciae evident at extreme sides of the more basal terga, more or less complete on T4 and T5, discal pubescence rather sparse, largely black but with pale hairs evident toward sides, length of discal pubescence exceeding apical margin of all terga when viewed laterally, T1 covered with copious, elongate, whitish pubescence; punctures very fine, surface shining, punctures close and fine on T2, quite sparse on T3 and T4, becoming somewhat coarser laterally, but still well separated, T5 with somewhat closer and coarser punctures throughout; T6 shining, carina very low, broadly and shallowly in-curved medially, punctures fine and close above carina, separated by 1 pd, becoming somewhat more coarse and sparse laterally, inner teeth of apical margin broadly carinate, widely separated, relatively near the short, acute, lateral teeth; T7 quite prominent, broad and short, with a deep excavation on dorsal surface, 2) S1-S4 exposed, closely but rather obscurely punctate, apical margins of S2-S4 broadly yellowish-hyaline and with thin, apical fringes of pale hairs.
Genitalia. Plate 2, Figure G16.
Discussion. This is the first report of the synonymy of M. nivalis with M. lapponica, based on both morphological similarities and CO1, thus making this one of three species of Megachile with a Holarctic distribution. The male of M. lapponica can only be distinguished with certainty from M. relativa by examining the genitalia (see Sheffield and Westby 2007; as M. nivalis). This species is a cavity nest and accepts trap-nests (Table 1).
Distribution. Widespread in Canada from NB-BC, though much more common in montane and boreal areas of the west (see Map 16).