Lasioglossum (Dialictus)

Gibbs, Jason, 2011, Revision of the metallic Lasioglossum (Dialictus) of eastern North America (Hymenoptera: Halictidae: Halictini), Zootaxa 3073, pp. 1-216 : 13-26

Key to female metallic Lasioglossum (Dialictus) of eastern North America

1. Nest-building species; metafemur with strong scopa; labrum with apical process narrow ( Fig. 6 A), dorsal keel present..... 2 - Socially parasitic species; metafemur with scopa weak or absent; labrum with apical process wide ( Fig. 6 B), dorsal keel absent................................................................................................... 99

2. Metasomal terga black, brown or metallic.................................................................. 3

- Metasomal terga pale brownish yellow to dark red.......................................................... 91

3. Tegula ovoid, obscurely punctate ( Fig. 7 B; except distinctly punctate in L. nymphaearum (Robertson)) ................ 4

- Tegula enlarged with distinct posterior angle, distinctly punctate ( Fig. 7 A)....................................... 86

4. Procoxa with conical projection ( Fig. 8 A) (propodeal dorsolateral slope with ventral margin defined by V- or U-shaped carina)................................................................................. L. illinoense (Robertson)

- Procoxa without conical projection ( Fig. 8 B) (propodeal dorsolateral slope with ventral margin variable, usually without V- or U-shaped carina).................................................................................... 5

5. T1 declivitous surface with acarinarial fan of appressed hairs present, sometimes with wide dorsal/medial opening; T1 declivitous surface without erect hairs basomedially ( Fig. 9 A)...................................................... 6

- T1 declivitous surface with acarinarial fan of appressed hairs absent; T1 declivitous surface with erect hairs basomedially ( Fig. 9 B).............................................................................................. 84

6. Mesosoma coarsely sculptured (mesoscutal punctures coarse, mesepisternum coarsely rugose or reticulate, etc.) and propodeal lateral and posterior surfaces separated by strong lateral carina ( Fig. 2 A)......................................... 7

- Mesosoma without combination above (i. e. mesoscutal punctures fine or mesepisternum rugulose or punctate or propodeal lateral and posterior surfaces incompletely separated by lateral carina; Figs. 2 C–2F)................................ 12

7. Hypostomal carinae widely divergent towards mandible bases ( Figs. 10 C, 11B); mesoscutum laterad of parapsidal line reticulate-rugose ( Fig. 4 A).................................................................................. 8

- Hypostomal carinae parallel ( Fig. 10 A, 11A); mesoscutum laterad of parapsidal line punctate ( Fig. 4 B) or coarsely rugose … 9

8. Protrochanter with anterior surface excavated; hypostomal carinae usually strongly produced, visibly protruding in lateral view................................................................................... L. bruneri (Crawford)

- Protrochanter without anterior surface excavated; hypostomal carinae not strongly produced, not visibly protruding in lateral view........................................................................... L. reticulatum (Robertson)

9 (7). Mesoscutum coarsely rugose laterally ( Fig. 127 ); pronotal ridge sharply angled.................... L. hartii (Robertson)

- Mesoscutum distinctly punctate laterally; pronotal ridge broadly rounded....................................... 10

10. Transverse propodeal carina not interrupted medially; tegula distinctly punctate; hypostomal carina produced distally, protruding in lateral view.............................................................. L. nymphaearum (Robertson)

- Transverse propodeal carina, if present, interrupted medially; tegula obscurely punctate; hypostomal carina not produced distally.............................................................................................. 11

11. Mesoscutal punctures between parapsidal lines sparse (i=1–3d); head and mesosoma usually blue; wings white with pale venation............................................................................. L. albipenne (Robertson)

- Mesoscutal punctures between parapsidal lines relatively dense (i=1–1.5d); head and mesosoma greenish; wings faintly dusky with amber venation................................................................ L. cressonii (Robertson)

12 (6). Mesoscutal punctures laterad of parapsidal line dense, interspaces mostly less than 1.5 puncture diameters (i≤1.5d) ( Figs. 4 B– 4D, 12B)........................................................................................... 13

- Mesoscutal punctures laterad of parapsidal line sparse, interspaces mostly greater than 1.5 puncture diameters (i=1.5–3d) ( Figs. 4 I, 12A)...................................................................................... 77

13. Mesoscutal punctures between parapsidal lines sparse, interspaces greater than puncture diameter (i>d) ( Figs. 4 A–4F, 4H, 4I, 13B).............................................................................................. 14

- Mesoscutal punctures between parapsidal lines dense, interspaces less than puncture diameter (i<d) ( Figs. 4 G, 13A)..... 68

14. T1 with distinct transverse band of appressed hairs at boundary of dorsal and declivitous surfaces, hair band separated from acarinarial fan by transverse glabrate area ( Fig. 14 A)........................................ L. disparile (Cresson)

- T1 not as above, with, at most, scattered erect hairs at boundary of dorsal and declivitous surfaces ( Fig. 14 B)........... 15

15. Supraclypeal area greatly convex; parapsidal line broad, wider than two puncture diameters ( Fig. 15 B).................................................................................................. L. foveolatum (Robertson)

- Supraclypeal area at most slightly convex; parapsidal line narrow, not wider than one puncture diameter ( Fig. 15 A)....... 16

16. Head round to wide (length/width ratio <1.02); supraclypeal area usually wider than long.......................... 17

- Head elongate (length/width ratio> 1.03); supraclypeal area longer than wide.................................... 62

17. T1 acarinarial fan incomplete, with medial opening ( Fig. 16 B)............................................... 18

- T1 acarinarial fan complete, without medial opening ( Fig. 16 A).............................................. 45

18. Mesepisternal sculpture with sharp division between coarsely rugose dorsal half and imbricate-punctate ventral half ( Fig. 17 B)................................................................................. L. dreisbachi (Mitchell)

- Mesepisternal sculpture without sharp division between dorsal and ventral halves ( Fig. 17 A)......................... 19

19. Protrochanter broad, width subequal to length ( Fig. 18 B); mandible with dorsal margin strongly curved, narrowing suddenly at midlength ( Fig. 19 B)................................................................ L. callidum (Sandhouse)

- Protrochanter narrow, width approximately ½ length ( Fig. 18 A); mandible without dorsal margin strongly curved, narrowing gradually over total length ( Fig. 19 A).................................................................... 20

20. Hypostomal carinae divergent towards mandible bases ( Fig. 10 B); (head often wider than mesosoma)................................................................................................. L. heterognathum (Mitchell)

- Hypostomal carinae parallel ( Fig. 10 A); (head usually narrower than mesosoma)................................. 21

21. T3–T4 with uniquely thick, evenly spaced, longitudinally oriented hairs ( Fig. 20 A); (size small)....... L. imitatum (Smith)

- T3–T4 without thick, evenly spaced, longitudinally oriented hairs ( Fig. 20 B); (size variable)........................ 22

22. Mesepisternum rugulose, tessellate or weakly punctate, posterior portion relatively unsculptured, area anterior to mesocoxa never coarsely rugoso-carinulate........................................................................ 23

- Mesepisternum rugose, posterior portion distinctly sculptured, area anterior to mesocoxa usually coarsely rugoso-carinulate ( Fig. 17 A)......................................................................................... 44

23. Clypeus with margin distal to preapical fimbriae narrow, appearing as a continuation of the lateral margins converging below the suborbital line (i. e. clypeal margin with trapezoidal appearance) ( Fig. 21 A)................................... 24

- Clypeus with margin distal to preapical fimbriae wide, appearing divergent from the lateral margins converging below the sub- orbital line (i. e. clypeal margin with rectangular appearance) ( Fig. 21 B)........................................ 42

24. T2–T4 with tomentum at least forming distinct basolateral patches; T3–T4 apical fringes present, usually dense ( Fig. 22 B)...................................................................................................... 25

- T2–T4 with very sparse, virtually absent tomentum, at most limited to scattered basolateral hairs, T3–T4 apical fringes absent or very sparse ( Fig. 22 A)............................................................................... 36

25. T1 anterior surface dull due to presence of distinct, transversely lineolate, microsculpture.......................... 26

- T1 anterior surface polished due to nearly complete absence of microsculpture................................... 30

26. T1 acarinarial fan with wide dorsal/medial opening, approximately equal to width of lateral hair patches; T3 apical margin brownish yellow with distinct apical fringe............................................................... 27

- T1 acarinarial fan with narrow dorsal/medial opening, much less wide than lateral hair patches; T3 apical margin dark reddish brown without distinct apical fringe..................................................................... 29

27. Gena wider than eye; clypeus distinctly flat................................................ L. apocyni (Mitchell)

- Gena narrower than eye; clypeus slightly convex........................................................... 28

28. Mesoscutum tessellate; T3–T4 with abundant tomentum and dense apical hairs forming dense apical fringes; lower paraocular area with dense punctures (i≤d)........................................... L. paradmirandum (Knerer and Atwood)

- Mesoscutum weakly imbricate; T3–T4 with moderately sparse tomentum and sparse apical hairs forming sparse apical fringes; lower paraocular area with relatively sparse punctures (i=1–1.5d)................................ L. fattigi (Mitchell)

29 (26). T2 apical impressed area impunctate; gena usually subequal to eye.................... L. laevissimum (Smith) [in part]

- T2 apical impressed area punctate; gena narrower than eye............................ L. gotham Gibbs , new species

30 (25). Metapostnotal rugae not extending much more than halfway to posterior margin ( Fig. 23 B); metasomal terga with metallic reflections; mesepisternum distinctly but minutely punctate............................. L. zephyrum (Smith) [in part]

- Metapostnotal rugae extending more than 2/3 distance to posterior margin ( Fig. 23 A); metasomal terga usually brown; mese- pisternum at most obscurely punctate.................................................................... 31

31. T2 apical impressed area with dense and distinct punctures, not interrupted or sparser medially..................... 32

- T2 apical impressed area with sparse or obscure punctures, interrupted or sparser medially......................... 34

32. Mesoscutum polished posteriorly due to lack of distinct microsculpture; tegula pale; clypeus not protruding much below sub- orbital line................................................................ L. trigeminum Gibbs , new species

- Mesoscutum dull posteriorly due to presence of distinct microsculpture; tegula pale to brown; clypeus variable......... 33

33. Tegula usually dark brown; clypeus protruding ½ below suborbital line; T2 apical impressed area with narrow testaceous bor- der.............................................................................. L. versatum (Robertson)

- Tegula pale straw; clypeus protruding 2/3 below suborbital line; T2 apical impressed area with wide testaceous border.................................................................................... L. admirandum (Sandhouse)

34 (31). Supraclypeal area densely punctate, interspaces mostly less than puncture diameter (i≤d)........... L. sagax (Sandhouse)

- Supraclypeal area sparsely punctate, interspaces greater than puncture diameter at least medially (i=1–3d).............. 35

35. Mesoscutum dull due to microsculpture; metasomal terga lacking distinct metallic reflections.......... L. ephialtum Gibbs

- Mesoscutum polished due to microsculpture; metasomal terga with distinct metallic reflections (Sable Island, Nova Scotia)......................................................................................... L. sablense Gibbs

36. (24). Mesoscutum mostly polished due to weakness of microsculpture.............................................. 37

- Mesoscutum dull or weakly polished due to presence of distinct microsculpture................................... 38

37. T2 basomedially with relatively dense punctation, interspaces not greater than two puncture diameters (i<2d), apical impressed area with scattered punctures across surface........................................... L. subviridatum (Cockerell)

- T2 basomedially with sparse punctation, interspaces often greater than four puncture diameters (i=2–5d), apical impressed area with only a few lateral punctures........................................................ L. abanci (Crawford)

38 (36). Head relatively long (length/width ratio> 0.97); metapostnotal rugae not reaching posterior margin, sometimes medial carina usually distinctly longer than submedial rugae; metasomal terga with scattered basolateral tomentum................. 39

- Head relatively short (length/width ratio <0.95); metapostnotal rugae reaching posterior margin; metasomal terga with virtu- ally no tomentum.................................................................................... 40

39. T2 apical impressed area impunctate; mesepisternum impunctate; metapostnotum with medial carina noticeably longer than submedial rugae....................................................................... L. planatum (Lovell)

- T2 apical impressed area punctate laterally; mesepisternum obscurely punctate; metapostnotum without medial carina longer than submedial rugae.............................................................. L. taylorae Gibbs [in part]

40 (38). Mesoscutal punctures relatively dense between parapsidal lines, interspaces often less than 1.5 puncture diameters (i=1–1.5d); mesepisternum punctate............................................................. L. subversans (Mitchell)

- Mesoscutal punctures relatively sparse between parapsidal lines, interspaces often equal to 2 puncture diameters (i=1–2.5d); mesepisternum impunctate............................................................................. 41

41. Head and mesosoma bluish; mesoscutal punctures and mesepisternal rugae relatively coarse; tegula dark reddish brown........................................................................................ L. oblongum (Lovell)

- Head and mesosoma greenish; mesoscutal punctures and mesepisternal rugae relatively fine; tegula pale yellow............................................................................................ L. alachuense (Mitchell)

42 (23). Mesoscutum polished due to weak microsculpture; metatibia with extensive yellowish areas not limited to ends (Southern)..................................................................................... L. leviense (Mitchell)

- Mesoscutum dull due to microsculpture; metatibia with yellowish areas limited to ends............................. 43

43. T1 acarinarial fan with narrow dorsal opening, clearly narrower than lateral acarinarial patches... L. mitchelli Gibbs [in part]

- T1 acarinarial fan with wide dorsal opening, nearly as wide as lateral acarinarial patches............. L. weemsi (Mitchell)

44 (22). Head and mesosoma bluish; supraclypeal area sparsely punctate (i=1–4d); metapostnotum with rugae not reaching posterior margin; T4 with very sparse tomentum not obscuring surface...................................... L. atwoodi Gibbs

- Head and mesosoma greenish; supraclypeal area more densely punctate (i=1–2d); metapostnotum with rugae reaching or nearly reaching posterior margin; T4 with sparse tomentum partially obscuring surface............. L. viridatum (Lovell)

45 (17). Mesepisternum rugulose to reticulate without distinct punctures ( Fig. 24 B)...................................... 46

- Mesepisternum smooth with distinct punctures ( Fig. 24 A).................................................... 53

46. Clypeus with margin distal to preapical fimbriae wide, appearing divergent from the lateral margins converging below the sub- orbital line (i. e. clypeal margin with rectangular appearance) ( Fig. 21 B)..................... L. mitchelli Gibbs [in part]

- Clypeus with margin distal to preapical fimbriae narrow, appearing as a continuation of the lateral margins converging below the suborbital line (i. e. clypeal margin with trapezoidal appearance) ( Fig. 21 A).................................... 47

47. Mesoscutal punctures relatively dense between parapsidal lines (i=1–1.5d); propodeum with oblique carina very fine, obscure or absent ( Fig. 2 D–2F)................................................................................ 48

- Mesoscutal punctures relatively sparse between parapsidal lines (i=1–2.5d); propodeum with oblique carina fine but distinctly present ( Fig. 2 B, 2C).................................................................................. 51

48. Postgena lineate; mesoscutal punctures relatively coarse ( Fig. 76 ); T1 acarinarial fan sparse.......... L. ceanothi (Mitchell)

- Postgena polished due to weak microsculpture; mesoscutal punctures fine; T1 acarinarial fan dense................... 49

49. Metasomal terga relatively dull, light brown basally not contrasting sharply with pale apical margins; T2 apical impressed area not distinctly punctate....................................................... L. katherineae Gibbs , new species

- Metasomal terga relatively shiny, green to black basally contrasting sharply with pale apical margins; T2 apical impressed area distinctly punctate.................................................................................... 50

50. Metapostnotal rugae longitudinal; T1 acarinarial fan medially interrupted by subdorsal, inverted triangular, glabrous patch................................................................... L. georgeickworti Gibbs , new species [in part]

- Metapostnotal rugae anastomosing; T1 acarinarial fan not interrupted by glabrous area.......... L. sheffieldi Gibbs [in part]

51 (47). Metasoma bright blue, without distinct patches of tomentum........................ L. coeruleum (Robertson) [in part]

- Metasoma brown to black, with distinct patches of tomentum.................................................. 52

52. Propodeum with dorsolateral slope rugose ( Fig. 25 A); mesepisternum rugose; T3–T5 with hairs forming apical fringe.............................................................................................. L. timothyi Gibbs

- Propodeum with dorsolateral slope ruguloso-imbricate ( Fig. 25 B); mesepisternum rugulose; T3–T5 without hairs forming api- cal fringe........................................................................ L. smilacinae (Robertson)

53 (45). Tibiae and femora primarily orange-yellow............................................. L. tarponense (Mitchell)

- Tibiae and femora primarily brown....................................................................... 54

54. Metapostnotum with rugae reaching more than 2/3 distance to posterior margin ( Fig. 23 A).......................... 55

- Metapostnotum with rugae reaching ½ distance to posterior margin or less ( Fig. 23 B).............................. 61

55. T2 apical impressed areas with punctures absent or sparse; T3–T4 with tomentum absent or limited to basolateral portions ( Fig. 22 A).......................................................................................... 56

- T2 apical impressed areas with punctures relatively dense; T3–T4 with tomentum on majority of disc ( Fig. 22 B)......... 60

56. Body size relatively large; metasomal terga distinctly blue or black............................................. 57

- Body size relatively small; metasomal terga light brown to golden green......................................... 58

57. Body entirely blue.......................................................... L. coeruleum (Robertson) [in part]

- Head and mesosoma golden green, metasoma black.............................. L. nigroviride (Graenicher) [in part]

58 (56). Submarginal cells two ( Fig. 5 B); mesepisternal punctures contiguous........................ L. anomalum (Robertson)

- Submarginal cells three ( Fig. 5 A); mesepisternal punctures distinctly separated.................................... 59

59. Head and mesosoma golden green; mesoscutum with yellowish woolly hairs; metasomal terga with metallic reflections........................................................................................... L. cattellae (Ellis)

- Head and mesosoma bluish; mesoscutum with dull whitish woolly hairs; metasomal terga without metallic reflections........................................................................................... L. tenax (Sandhouse)

60 (55). Metapostnotal rugae longitudinal; T1 acarinarial fan medially interrupted by subdorsal, inverted triangular, glabrous patch................................................................. L. georgeickworti Gibbs , new species [in part]

- Metapostnotal rugae anastomosing; T1 acarinarial fan not interrupted by glabrous area.......... L. sheffieldi Gibbs [in part]

61 (54). Metasomal terga without metallic reflections; lower paraocular without dense tomentum; gena narrower than eye (south-eastern)........................................................................ L. flaveriae (Mitchell) [in part]

- Metasomal terga with green metallic reflections; lower paraocular area with dense tomentum; gena usually wider than eye................................................................................ L. zephyrum (Smith) [in part]

62 (16). Metasoma metallic, T3–T4 mostly obscured by dense white tomentum....................... L. pruinosum (Robertson)

- Metasoma non-metallic, T3–T4 only partially obscured by relatively sparse tomentum.............................. 63

63. Mesoscutal punctures between parapsidal lines relatively sparse, often more than 2 punctures diameter apart ( Fig. 122 )... 64

- Mesoscutal punctures between parapsidal lines relatively dense, only separated by 1 puncture diameter medially ( Fig. 205 )..................................................................................................... 67

64. Metapostnotal rugae distinct on weakly imbricate background; (T1 acarinarial fan with dorsal opening)................................................................................................. L. taylorae Gibbs [in part]

- Metapostnotal rugae very fine, obscure on tessellate background; (T1 acarinarial fan variable)........................ 65

65. Mesoscutal punctures immediately mesad of parapsidal line dense, interspaces not greater than puncture diameter (i≤d) ( Fig. 122 )........................................................................... L. halophitum (Graenicher)

- Mesoscutal punctures immediately mesad of parapsidal line sparse, interspaces greater than puncture diameter (i=2–4d) ( Fig. 80 )................................................................................................ 66

66. Face relatively short (length/width ratio = 1.09–1.13) ( Fig. 79 B); T1 acarinarial fan dense dorsally ( Fig. 80 )......................................................................................... L. coreopsis (Robertson) [in part]

- Face relatively long (length/width ratio = 1.20–1.21) ( Fig. 150 B); T1 acarinarial fan sparse dorsally ( Fig. 151 ) (Southern)................................................................................ L. longifrons ( Baker) [in part]

67 (63). T1 acarinarial fan small, dorsomedially without erect hairs ( Fig. 86 ); T2 apical impressed area dull, punctures obscure; mesoscutellum usually with submedial punctures widely spaced, interspaces greater than puncture diameter (i=1–3d).................................................................................. L. creberrimum (Smith) [in part]

- T1 acarinarial fan large, dorsomedially with erect hairs ( Fig. 205 ); T2 apical impressed area smooth, punctures distinct; mesoscutellum with submedial punctures uniformly dense, interspaces not greater than puncture diameter (i≤d)...................................................................................... L. tamiamense (Mitchell) [in part]

68 (13). Head relatively elongate (length/width ratio = 1.00–1.10); mesepisternum rugulose................................ 69

- Head relatively wide (length/width ratio = 0.95–0.99); mesepisternum at least obscurely punctate..................... 76

69. Metapostnotal rugae high and distinct, background microsculpture imbricate; (metasoma metallic blue or green)......... 70

- Metapostnotal rugae low and indistinct, background microsculpture granular (e.g. Fig. 205 ); (metasoma brown, except for L. floridanum (Robertson)) ............................................................................... 72

70. Lateral margins of clypeus below suborbital line subparallel distally; pubescence yellowish............. L. pilosum (Smith)

- Lateral margins of clypeus below suborbital line convergent distally, if nearly parallel then pubescence dull white........ 71

71. Pubescence yellowish to dull white; supraclypeal area relatively short, 0.65–0.86 times length of clypeus (eastern).......................................................................................... L. leucocomum (Lovell)

- Pubescence dull white; supraclypeal area relatively long, 0.80–0.90 times length of clypeus (Midwestern)................................................................................................... L. succinipenne (Ellis)

72 (69). Metasomal terga metallic green; wings relatively hyaline; pterostigma pale honey-coloured...... L. floridanum (Robertson)

- Metasomal terga brown; wings relatively dusky; pterostigma brown............................................ 73

73. Supraclypeal area distinctly flat; T2 apical impressed areas with deep and distinct punctures; head shorter (length/width ratio = 1.00–1.05).......................................................................................... 74

- Supraclypeal area slightly convex; T2 apical impressed areas with shallow and indistinct punctures; head longer (length/width ratio = 1.05–1.09)................................................................................... 75

74. Supraclypeal area polished due to lack of microsculpture ( Fig. 69 B); clypeus with apical margin laterally reddish brown ( Fig. 69 B).......................................................................... L. batya Gibbs , new species

- Supraclypeal area dull due to imbricate microsculpture ( Fig. 170 B); clypeus with apical margin entirely brown ( Fig. 170 B).................................................................................. L. raleighense (Crawford)

75 (73). T1 acarinarial fan small, dorsomedially without erect hairs ( Fig. 86 ); T2 apical impressed area dull, punctures obscure; mesoscutellum usually with submedial punctures widely spaced, interspaces greater than puncture diameter (i=1–3d).................................................................................. L. creberrimum (Smith) [in part]

- T1 acarinarial fan large, dorsomedially with erect hairs ( Fig. 205 ); T2 apical impressed area smooth, punctures distinct; mesoscutellum with submedial punctures uniformly dense, interspaces not greater than puncture diameter (i≤d)...................................................................................... L. tamiamense (Mitchell) [in part]

76 (68). T3 usually obscured by dense tomentum; postgena polished due to lack of microsculpture; mesoscutum polished, at least submedially........................................................................... L. perpunctatum (Ellis)

- T3 with tomentum limited to basolateral portions; postgena dull due to lineolate microsculpture; mesoscutum imbricate throughout (south-eastern)........................................................... L. miniatulum (Mitchell)

77 (12). Mesepisternum relatively smooth with distinct punctures..................................................... 78

- Mesepisternum rugulose without distinct punctures.......................................................... 79

78. T3–T5 apical impressed areas without hairs forming apical fringes; size large, head width = 1.94–2.11 mm; propodeal carinae and sculpture coarser ( Fig. 26 B).............................................. L. nigroviride (Graenicher) [in part]

- T3–T5 apical impressed areas with hairs forming weak apical fringes; size normal, head width = 1.44–1.58 mm; propodeal carinae and sculpture finer ( Fig. 26 A)..................................................... L. obscurum (Robertson)

79 (77). Frons punctures dense; size large, head width = 1.70–182 mm; oblique carina linear, transversely directed (i. e. not U- or V- shaped)............................................................................................ 80

- Frons punctures sparse; size small, head width = 1.06–1.49 mm; oblique carina angular, with both transversely and longitudi- nally directed branches (i. e. U- or V-shaped)............................................................... 83

80. Face long (length/width ratio = 1.09–1.21); mesoscutum strongly tessellate....................................... 81

- Face short (length/width ratio = 0.92–0.96); mesoscutum imbricate............................................. 82

81. Face relatively short (length/width ratio = 1.09–1.13) ( Fig. 79 B); T1 acarinarial fan dense dorsally ( Fig. 80 )......................................................................................... L. coreopsis (Robertson) [in part]

- Face relatively long (length/width ratio = 1.20–1.21) ( Fig. 150 B); T1 acarinarial fan sparse dorsally ( Fig. 151 ) (Southern)................................................................................ L. longifrons ( Baker) [in part]

82 (80). Head round (length/width ratio = 0.92–0.93), clypeus weakly protruding below suborbital line; propodeal dorsolateral slope imbricate ( Fig. 27 A)................................................................ L. lineatulum (Crawford)

- Head relatively long (length/width ratio = 0.95–0.96), clypeus strongly protruding below suborbital line; propodeal dorsolat- eral slope rugose ( Fig. 27 B) (Boreal, uncommon in USA)................................... L. novascotiae (Mitchell)

83 (79) Mesoscutum polished due to lack of microsculpture (north-eastern, rare)......................... L. achilleae (Mitchell)

- Mesoscutum dull due to presence of microsculpture (south-eastern, common).................... L. apopkense (Mitchell)

84 (5). Propodeal lateral and posterior surfaces completely separated by lateral carina ( Fig. 28 B).......... L. rufulipes (Cockerell)

- Propodeal lateral and posterior surfaces incompletely separated by lateral carina ( Fig. 28 A).......................... 85

85. Metapostnotal rugae not extending more than 2/3 distance to posterior margin....................... L. versans (Lovell)

- Metapostnotal rugae extending ¾ or more of distance to posterior margin (rare, see comments below)..................................................................................................... L. hemimelas (Cockerell)

86 (3). Metasoma usually with distinct metallic reflections; size larger, head width> 1.7 mm (coastal sand dune specialist).......................................................................................... L. marinum (Graenicher)

- Metasoma without distinct metallic reflections; size smaller, head width <1.5 mm ................................. 87

87. Mesepisternum shining between punctures due to weak microsculpture......................... L. ellisiae (Sandhouse)

- Mesepisternum dull between punctures due to microsculpture................................................. 88

88. Head and mesosoma usually blue; head relatively elongate (length/width ratio = 0.95–1.10) (south-eastern)................................................................................................... L. puteulanum Gibbs

- Head and mesosoma green with at most bluish reflections; head relatively short (length/width ratio = 0.85–1.00).............................................................................................................. 89

89. Inner hind tibial spur pectinate with 2 branches (not including apex of rachis) (rare, Illinois)......... L. carlinvillense Gibbs

- Inner hind tibial spur pectinate with 3 or more branches (not including apex of rachis).............................. 90

90. Paraocular area with dense tomentum obscuring surface; metapostnotal rugae anastomosing (Florida)....................................................................................................... L. lepidii (Graenicher)

- Paraocular area with sparse tomentum not obscuring surface; metapostnotal rugae longitudinal (mid-eastern)................................................................................................ L. tegulare (Robertson)

91 (2). Mesoscutum densely covered in yellowish tomentum, integument mostly or entirely obscured ( Fig. 29 B).................................................................................................... L. vierecki (Crawford)

- Mesoscutum not densely covered with tomentum, integument not obscured ( Fig. 29 A).............................. 92

92. Mesepisternum punctate-reticulate....................................................................... 93

- Mesepisternum impunctate............................................................................. 98

93. Metapostnotum rugose, with rugae reaching or nearly reaching posterior margin................................... 94

- Metapostnotum smooth, at most with weak rugae limited to basal margin (Southern Florida)......................... 97

94. Clypeus with apical margin reddish ( Figs. 164 B, 200B) (South-eastern).......................................... 95

- Clypeus with apical margin dark brown ( Fig. 62 B) (Mid-western, North-eastern).................................. 96

95. Tegula elongate with posterior angle ( Fig. 201 )............................................. L. surianae (Mitchell)

- Tegula ovoid without posterior angle ( Fig. 165 ).............................................. L. nymphale (Smith)

96 (94). Postgena polished distally due to lack of microsculpture; metasomal terga yellowish orange (Midwestern)................................................................................................... L. pictum (Crawford)

- Postgena dull distally due to lineolate microsculpture; metasomal terga reddish orange (Coastal).................................................................................................... L. arantium Gibbs , new species

97 (93). Dull metallic; three submarginal cells; metapostnotum with basal rugae ( Fig. 99 ).......... L. flaveriae (Mitchell) [in part]

- Brilliant iridescent; two submarginal cells; metapostnotum without rugae....................... L. eleutherense (Engel)

98 (92). Propodeum with strong lateral carina reaching dorsal margin ( Fig. 28 B) (Midwestern/Boreal)..... L. testaceum (Robertson)

- Propodeum with weak lateral carina not reaching dorsal margin ( Fig. 28 A) (Florida).............. L. stuartense (Mitchell)

99 (1). Gena width greater than eye in lateral view; mandible greatly enlarged, usually extending well beyond opposing clypeal angle.................................................................................................. 100

- Gena width subequal to eye in lateral view; mandible only slightly enlarged, not extending much or at all past opposing clypeal angle............................................................................................. 107

100. Metapostnotum smooth, with weak rugae limited to basal margin.............................................. 101

- Metapostnotum rugose, with rugae reaching or nearly reaching posterior margin.................................. 102

101. Size small, head width 1.25–1.30 mm .................................................. L. lionotum (Sandhouse)

- Size large, head width 1.80–2.02 mm .................................................. L. cephalotes (Robertson)

102 (100). Mandible without preapical tooth ( Fig. 30 A)........................................................... 103

- Mandible with distinct preapical tooth ( Fig. 30 B).......................................................... 105

103. Mesepisternum distinctly punctate................................................. L. ascheri Gibbs , new species

- Mesepisternum rugulose.............................................................................. 104

104. Mandible narrow, evenly convergent over entire length; labrum with weak basal tubercle....... L. rozeni Gibbs , new species

- Mandible wide, strongly convergent near apex; labrum with strong basal tubercle....... L. platyparium (Robertson) [in part]

105 (102). Mesepisternum rugulose; mandible preapical tooth very small................... L. platyparium (Dalla Torre) [in part]

- Mesepisternum vertically carinulate or smooth and punctate; mandible preapical tooth relatively large................ 106

106. Mesepisternum vertically carinulate, impunctate........................................ L. michiganense (Mitchell)

- Mesepisternum smooth, punctate................................................ L. curculum Gibbs , new species

107 (99). Pronotal ridge smoothly rounded; mandible without preapical tooth........................... L. simplex (Robertson)

- Pronotal ridge sharply angled; mandible with or without preapical tooth........................................ 108

108. Mandible with preapical tooth; inner metatibial spur usually with 3 branches.............. L. izawsum Gibbs , new species

- Mandible without preapical tooth; inner metatibial spur with 4 branches................ L. furunculum Gibbs , new species

Figures

FIGURE 2. Propodeum and metapostnotum variation in female Lasioglossum (Dialictus). (A) L. cressonii, (B) L. nigroviride, (C) L. lineatulum, (D) L. coreopsis, (E) L. connexum, (F) L. (D.) sp.

FIGURE 4. Mesoscutum of female Lasioglossum (Dialictus) showing sculpture and punctation variation. (A) L. reticulatum, (B) L. cressonii, (C), L. nymphaearum, (D). L. (D.) sp., (E) L. heterognathum, (F) L. coreopsis, (G) L. pilosum, (H) L. nigroviride, (I) L. lineatulum.

FIGURE 5. Forewings of female Lasioglossum subgenus Dialictus. (A) Typical forewing with three submarginal cells. Pterostigma (pt), basal vein (b), arrows indicate weakened veins. (B) Forewing with two submarginal cells. Arrows indicate weakened veins. (From Gibbs 2010 b).

FIGURE 6. Labrum of female Dialictus; (A) nest-building species, (B) parasitic species. Arrows indicate apical process. (From Gibbs 2010 b).

FIGURE 7. Tegula (A) punctate, enlarged, punctate with posterior angle (B) ovoid, without posterior angle (L. nymphaearum). (From Gibbs 2010 b).

FIGURE 8. Procoxa (A) with conical projection (L. illinoense), (B) without conical projection (From Gibbs 2010 b).

FIGURE 9. Declivitous surface of T 1 with acarinarial fan (A) present, (B) absent. (From Gibbs 2010 b).

FIGURE 10. Hypostomal carina variation in female Lasioglossum (Dialictus). (A) subparallel (L. connexum); (B) divergent (L. heterognathum); (C) divergent (L. reticulatum).

FIGURE 15. Parapsidal line of mesoscutum, indicated by arrow, (A) narrow, (B) wide (L. foveolatum). (From Gibbs 2010 b).

FIGURE 17. Mesepisternum (A) without distinct change in sculpture (B) with distinct change in sculpture, indicated by arrow (L. dreisbachi). (From Gibbs 2010 b).

FIGURE 18. Protrochanter (A) narrow, (B) wide (female L. callidum). (From Gibbs 2010 b).

FIGURE 19. Mandible of female (A) without strongly curved dorsal margin, (B) with strongly curved dorsal margin (L. callidum). (From Gibbs 2010 b).

FIGURE 21. Margin of clypeus (A) L. admirandum, (B) L. mitchelli.

FIGURE 22. Metasomal terga (A) without basolateral tomentum or apical fringes, (B) with basolateral tomentum and apical fringes. (From Gibbs 2010 b).

FIGURE 23. Metapostnotal rugae (A) nearly reaching posterior margin, (B) extending halfway to posterior margin. (From Gibbs 2010 b).

FIGURE 24. Mesepisternum (A) punctate, (B) impunctate (rugulose). (From Gibbs 2010 b).

FIGURE 25. Metapostnotum (A) L. timothyi, (B) L. smilacinae. (From Gibbs 2010 b).

FIGURE 26. Metapostnotum (A) L. obscurum, (B) L. nigroviride. (From Gibbs 2010 b).

FIGURE 27. Dorsolateral slope of propodeum (A) L. lineatulum, (B) L. smilacinae. (From Gibbs 2010 b).

FIGURE 28. Propodeal carinae (A) weak, (B) strong. (From Gibbs 2010 b).

FIGURE 29. Mesoscutum (A) not obscured by tomentum, (B) obscured by tomentum (L. vierecki). (From Gibbs 2010 b).

FIGURE 30. Mandible (A) without preapical tooth, (B) with preapical tooth (indicated by arrow). (From Gibbs 2010 b).

FIGURE 62. Lasioglossum arantium Gibbs female, (A) lateral habitus, (B) face. Scale bars = 1 mm.

FIGURE 69. Lasioglossum batya Gibbs female, (A) lateral habitus, (B) face. Scale bars = 1 mm.

FIGURE 76. Lasioglossum ceanothi (Mitchell) female, dorsal view of mesosoma.

FIGURE 79. Lasioglossum coreopsis (Robertson) female, (A) lateral habitus, (B) face. Scale bars = 1 mm.

FIGURE 80. Lasioglossum coreopsis (Robertson) female, dorsal view of mesosoma.

FIGURE 86. Lasioglossum creberrimum (Smith) female, dorsal view of mesosoma.

FIGURE 99. Lasioglossum flaveriae (Mitchell) female, dorsal view of mesosoma.

FIGURE 122. Lasioglossum halophitum (Graenicher) female, dorsal view of mesosoma.

FIGURE 127. Lasioglossum hartii (Robertson) female, dorsal view of mesosoma.

FIGURE 150. Lasioglossum longifrons (Baker) female, (A) lateral habitus, (B) face. Scale bars = 1 mm.

FIGURE 151. Lasioglossum longifrons (Baker) female, dorsal view of mesosoma.

FIGURE 164. Lasioglossum nymphale (Smith) female, (A) lateral habitus, (B) face. Scale bars = 1 mm.

FIGURE 165. Lasioglossum nymphale (Smith) female, dorsal view of mesosoma.

FIGURE 170. Lasioglossum raleighense (Crawford) female, (A) lateral habitus, (B) face. Scale bars = 1 mm.

FIGURE 201. Lasioglossum surianae (Mitchell) female, dorsal view of mesosoma.

FIGURE 205. Lasioglossum tamiamense (Mitchell) female, dorsal view of mesosoma.

FIGURE 14. T 1 Acarinarial fan (A) with transverse glabrous area (L. disparile); (B) without transverse glabrous area (L. albipenne).

FIGURE 16. T 1 acarinarial fan (A) complete, without dorsal opening, (B) incomplete, with dorsal opening. (From Gibbs 2010 b).

FIGURE 20. T 3 – T 4 (A) with uniquely coarse, evenly spaced, longitudinal hairs (L. imitatum); (B) without coarse hairs (L. laevissimum). (From Gibbs 2010 b).