Osmia (Acanthosmioides) unca, Michener, Michener

Rightmyer, Molly G. & Griswold, Terry, 2010, Description of a new species of Osmia (Hymenoptera: Megachilidae) from southwestern North America, with a redescription of the enigmatic species Osmia foxi Cameron, Zootaxa 2512, pp. 26-46 : 45-46

dark ..................................................................................................................... O . (Acanthosmioides) unca Michener - Mandible with third tooth relatively strong, well differentiated from fourth; mesepisternum with hairs white ........... ................................................................................................ O. (Acanthosmioides) palmula Rightmyer & Griswold Key to Males

1 Hind coxa with strong longitudinal carina along inner ventral angle; parapsidal line somewhat elongate; T6 lateral apical margin with distinct rounded lobe, this lobe in dorsal view appearing same length or longer than midpoint of tergum; S4 with dense, narrow comb of short, stout hairs on small midapical projection (T2 and T3 lacking impunctate bands at apical margins) ............................................................................ O . (Diceratosmia) subfasciata Cresson

- Hind coxa lacking or rarely with weak longitudinal carina along inner ventral angle; parapsidal line punctiform; T6 lacking or with weakly produced tooth or lobe on lateral apical margin, in dorsal view this lateral lobe distinctly shorter than midpoint of tergum (excluding midapical emargination, if present); S4 apical margin lacking dense, narrow comb of short, stout hairs (or, if comb of longer, stout hairs present, then these hairs arising from midapical emargination rather than projection) ............................................................................................................................ 2

2 Malar space as long as width of scape, at least on ventral half of malar space; integument adjacent to lower margin of eye sometimes with small, shallow, shining pit (propodeal triangle strongly granulose, dull; mesofemur with strong to weak ventral projection; T6 not or very weakly emarginate at midapical margin; gonoforceps subapically strongly swollen or with distinct secondary process arising subapically) .................................................................... 3

- Malar space rarely as long as width of scape and almost never that wide on entire ventral half (if malar space as wide as scape width, then without combination of other characters listed above); integument ventral to eye lacking depression ............................................................................................................................................................................... 4

3 Color blue-black to green-black; mesofemur with large, subtriangular ventral projection; hind basitarsal segment with tooth on inner margin; stridulus with malus long, acute; gonoforceps with relatively long, thin, subapical ventral projection ......................................................................................................................... O . (Osmia) lignaria Say

- Color metallic blue or green; mesofemur with a low, rounded ventral projection; hind basitarsal segment not toothed; stridulus with malus short; gonoforceps subapically swollen, without distinct subapical projection ............. ................................................................................................................ O. (Osmia) ribifloris biedermanni Michener

4 S2 with apical margin slightly convex, not covering S3 medially; apical margin of S3 lacking, or with very shallow, emargination medially, exposed from side to side; propodeal triangle strongly granulose (propodeal pit longer than wide; gonoforceps thickened, with vaguely differentiated dorsal ridge, lacking preapical swelling or secondary projection; labrum twice as long as median width, apical margin rounded; F1 less than three-fourths as long as F2) ...... .......................................................................................................... O. (Cephalosmia) montana quadriceps Cresson

- S2 with apical margin strongly convex, hiding S3 medially; apical margin of S3 usually broadly (sometimes more narrowly) emarginate with fringe of long hairs in emargination .................................................................................. 5

5 S4 with apical margin laterally consisting of two carinae, between which is a narrow, hairless, shining groove ..... 6

- S4 with apical margin thin, without groove ................................................................................................................ 7

6 S4 midapically with dense patch of hairs comprising at least one-third of total apical width of S4, hairs long and straight .............................................................................................................. O. (Helicosmia) coloradensis Cresson

- S4 midapically with dense patch of hairs one-fourth as wide as total apical width of S4, hairs short and hooked ....... ..................................................................................................................................... O . (Helicosmia) texana Cresson

7 S2 with midapical protuberance, this protuberance with minute apical hook in lateral view; S4 with small midapical spine (antenna crenulate; gonoforceps with distinct secondary process) .................................................................... 8

- S2 without distinct midapical protuberance; S4 lacking midapical spine ................................................................... 9

8 Mandible with inner margins of ventral and dorsal teeth forming strongly obtuse angle (about 160 degrees); dorsal tooth with dorsoapical angle rounded, strongly obtuse ......................... O . (Acanthosmioides) nigrobarbata Cockerell

- Apical edge of mandible distinctly V-shaped, with inner margins of ventral and dorsal teeth forming 125 degree angle or nearly so; dorsal tooth with dorsoapical angle pointed, about 90 degrees ....................................................... ............................................................................................................................ O . (Acanthosmioides) unca Michener

9 Body bright metallic blue, green, and/or purple, suggestive of chrysidid wasps .................................................... 10

- Body various shades of blue and green but not so brilliant as to suggest chrysidid wasps ....................................... 11

10 F11 slightly expanded apically; S6 with hairs on midapical projection hooked, stout; T7 with midapical emargination about as deep as wide or slightly deeper than wide; forewing 6 mm or more ... O. (Melanosmia) foxi Cameron

- F11 not expanded apically; S6 with hairs on midapical projection straight and relatively fine; T7 with midapical emargination much wider than deep; forewing 5 mm or less ............................. O . (Melanosmia) gaudiosa Cockerell

11 Flagellar segments strongly crenulate; F11 strongly flattened and distinctly wider than F10, F11 tinged with black, greatly contrasting with remaining orange flagellar segments (S4 midapically with dense patch of coarse, orange-

brown hairs, this patch of hairs weakly interrupted medially by longitudinal hairless stripe, and apical margin of S4 with medially uninterrupted fringe of stout orange-brown hairs; gonoforceps with secondary distal process, this process nearly three times as long as apical width) ..................... O. (Acanthosmioides) palmula Rightmyer & Griswold - Flagellar segments not or very weakly crenulate; F11 sometimes weakly flattened but never wider than preceding flagellar segments ...................................................................................................................................................... 12

12 T6 with apical margin greatly thickened, strongly convex, shining, not or very weakly emarginate; S2 with apical margin weakly emarginate (hair on body entirely white) ........................................................................................... 13

- T6 with apical margin variable, but not so strongly thickened and convex; S2 with apical margin rarely emarginate .................................................................................................................................................................................... 14

13 F1 much shorter than F2; forewing entirely clear; T2 with punctures extending nearly to apical margin (i.e., impunctate area only a puncture width in length or nearly so) ...................................... O . (Melanosmia) prunorum Cockerell

- F1 subequal to F 2 in length; forewing weakly infuscate distal to cells; T2 with distinct impunctate band at apical margin (i. e., about 3 puncture diameters in length) ........................................... O. (Melanosmia) liogastra Cockerell

14 F1 nearly half of F2 length; forewing entirely clear, with hairs in cells extremely sparse (nearly absent) and papillae weak (T3–T6 with hairs mostly black; T7 with tooth lateral to median emargination long and pointed; S4 midapical hairs black) ............................................................................................................... O . (Melanosmia) cerasi Cockerell

- F1 subequal to F 2 in length, if shorter then only three-fourths length of F2; forewing clear to infuscate, with hairs in cells relatively dense, papillae weak to strong .......................................................................................................... 15

15 T2 apical margin lacking or with extremely short impunctate band (i. e., one puncture diameter or less in length); wings clear, with hairs on wing relatively long and thick ......................................................................................... 16

- T2 apical margin with longer impunctate band (i. e., about two adjacent puncture diameters in length or more); wings clear or infuscate, with hairs relatively short and fine ... 17

16 Tegula translucent orange to pale brown; S4 with midapical hairs pale; gonoforceps relatively thin in lateral view, in dorsal view widest about a fourth from apical margin ............................................. O . (Melanosmia) titusi Cockerell

- Tegula opaque, usually with at least some metallic coloration on anterior corner; S4 with midapical hairs black; gonoforceps relatively thick in lateral view, in dorsal view nearly uniform in width along apical four-fifths, appearing slightly twisted apically ............................................................................ O . (Trichinosmia) latisulcata Michener

17 T6 with hairs entirely white ....................................................................................................................................... 18

- T6 with hairs mostly black, especially laterally ......................................................................................................... 19

18 T6 midapical emargination very deep (i. e., as deep as wide or even deeper than wide); T7 with tooth adjacent to midapical emargination triangular, about half as wide as emargination ....... Osmia (Melanosmia) trevoris Cockerell

- T6 midapical emargination very shallow (i. e., much wider than deep); T7 with tooth adjacent to midapical emargination spine-like, only about a fourth as wide as emargination ............................. O. (Melanosmia) cordata Robertson

19 Frons with punctures distinctly larger than those on vertex posterior to ocelli (punctures very dense and deep on frons); S4 with midapical hairs black ....................................................................... O. (Melanosmia) brevis Cresson

- Frons with punctures subequal to those on vertex posterior to ocelli; S4 with midapical hairs white .......................... ......................................................................................................................... O. (Melanosmia) clarescens Cockerell