Lasioglossum (Dialictus)
Creators: name: Gardner, Joel
name: Gibbs, Jason
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Halictidae
Lasioglossum

description: Identification keys to the western red-tailed species of Lasioglossum (Dialictus)
Key to females
1. Tegula enlarged, reaching or nearly reaching scutellum, with inner posterior margin straight or concave, often punctate (Fig. 91A)........................ L. hunteri (Crawford, 1932) and similar species 1
– Tegula ovoid, impunctate, and clearly not reaching scutellum (Fig. 91B)........................................ 2
1 L. parvum-tegulare species complex; not treated further herein. Specimens from desert and mountain regions are not likely true L. hunteri.
2. Head (except clypeus and postgena) and mesonotum entirely covered in dense, yellowish, thickly plumose hairs which (unless worn) largely obscure the surface underneath (Fig. 92); face relatively long (length/width ratio ~0.84).......................................................................................................... 3
– Head and mesonotum with thick hairs sparse or absent, or if more extensive, then hairs bright white and at least center of scutum largely exposed (Fig. 67A); face length variable ................................ 4
3. Thick hairs short and scale-like (Fig. 92A); body length 4.5–5 mm (sand dunes of eastern United States and Canada)................................................................................. L. vierecki (Crawford, 1904)
– Thick hairs long (Fig. 92B); body length 5.5–6 mm (mountains of California and western Nevada)........................................................................................................... L. cembrilacus sp. nov.
4. Mesonotum and mesepisternum entirely covered in strong tessellate to finely reticulate microsculpture, with fine, sparse punctures (i=1–4 pd) which are often obscured by microsculpture (Fig. 93A) (Mexico)........................................................................................................................... 5
– Mesonotum and/or mesepisternum usually shiny and distinctly punctate at least in part (Fig. 93C); if covered in strong microsculpture, then more densely punctate (Fig. 93B) (widespread).............. 6
5. Frons punctures large (about as large as paraocular area punctures) and coarse, approaching a rugulose condition (Fig. 94A); T1 anterior surface shiny (Fig. 95A) (widespread throughout most of Mexico)......................................................................................................... L. tessellatosum sp. nov.
– Frons punctures small (about half the size of paraocular punctures) and fine, at most very weakly rugulose above antennae (Fig. 94B); T1 anterior surface weakly coriarious (Fig. 95B) (Yucatan Peninsula) .......................................................................................................... L. meteorum sp. nov.
6. T1 with numerous erect hairs evenly distributed across anterior face; acarinarial fan absent (Fig. 96A) and/or metasomal terga with extremely narrow, abruptly downcurved rims usually with dense apicolateral fringes of long, plumose hair (Fig. 97A) ............................................................. 7
– T1 anterior face with erect hairs absent at least medially, usually limited to lateral margins; acarinarial fan present, although often weakly developed (Fig. 96B); metasomal terga with broad, flat rims with apicolateral fringes of short hair (Fig. 97B) .................................................................................... 13
7. Scutum shiny and moderately sparsely punctate submedially (i=1–2 pd) (Fig. 93C); face short (length/width ratio 0.88 or less)......................................................................................................... 8
– Scutum entirely finely and densely punctate (i ≤ 1 pd) and often dull (Fig. 93B); face long (length/ width ratio 0.88 or more) ................................................................................................................. 10
8. Propodeum with strong V-shaped oblique carina (Fig. 98A); T1 anterior face with no appressed hairs................................................................................................... L. testaceum (Robertson, 1897)
– Oblique carina absent (Fig. 98B); T1 anterior face with some appressed hairs ................................ 9
9. Metasomal terga with extremely narrow, abruptly downcurved rims usually with dense apicolateral fringes of long, plumose hair (Fig. 97A); frons shiny with distinctly separated punctures (Fig. 94C); T1 anterior face with numerous long appressed hairs forming weak acarinarial fan .......................... ............................................................................................................................ L. cactorum sp. nov.
– Metasomal terga with broad, flat rims with sparse apicolateral fringes of short, simple hair (Fig. 97B); frons densely reticulate-punctate (Fig. 94A); T1 anterior face with sparse, short appressed hairs laterally not forming distinct fan .................................................................. L. miltolepoides sp. nov.
10. Metasomal terga always, and scutum often mostly shiny; middle tibial spur and anterior hind tibial spur minutely serrate, appearing simple (Fig. 99A) (mountain species)..........................................11
– Metasomal terga and scutum entirely dull; middle tibial spur and anterior hind tibial spur finely pectinate with teeth nearly half the width of the rachis (Fig. 99B) (desert species)........................ 12
11. Malar space as wide or wider than scape; supraclypeal area much longer than broad; scutum with slightly sparser punctures, with numerous interspaces up to 1 puncture diameter or slightly more, and more extensively shiny on average (Utah to Colorado)........................ L. griswoldi Gibbs, 2009
– Malar space less than width of scape; supraclypeal area only slightly longer than broad; scutum with denser punctures, with only a few interspaces up to 1 puncture diameter, and less shiny on average (sometimes completely dull) (California to British Columbia)............. L. tuolumnense Gibbs, 2009
12. T4 tomentum limited to narrow basal band; T2–3 with basolateral tomentum covering much less than half length of segment (Baja California to Arizona)................... L. petrellum (Cockerell, 1903)
– T4 with sparse tomentum throughout; T2–3 with sparse basolateral tomentum covering about half length of segment laterally (New Mexico to Nuevo Leon)............................ L. droegei Gibbs, 2009
13. Forewing with all hairs white, often difficult to see; membrane hyaline; veins (excluding subcosta) usually pale amber (Fig. 100A) ....................................................................................................... 14
– Forewing with distinct, dark hairs in apical half or more; membrane sometimes infuscated; veins often dark brown (Fig. 100B).......................................................................................................... 26
14. Punctures of frons crowded (not all punctures are round), the surface thus appearing relatively dull (Fig. 94A), usually distinctly smaller and denser than punctures of paraocular area; and/or T1 anterior surface coriarious (Fig. 95 B–C)......................................................................................... 15
– Punctures of frons about the same size and density as punctures of paraocular area, with at least narrow shiny interspaces, the surface thus appearing shiny (Fig. 94 C–D); T1 anterior surface shiny (Fig. 95A) ........................................................................................................................................ 18
15. Supraclypeal area mostly or entirely tessellate (Fig. 101A); postgena mostly dull and/or lineate (Fig. 102A) ...................................................................................................................................... 16
– Supraclypeal area (Fig. 101B) and postgena (Fig. 102B) mostly smooth and shiny ...................... 17
16. Scutum mostly shiny with most punctures separated by about one puncture diameter (Fig. 75A); discs of terga black to reddish brown with metallic blue-green reflections.... L. rufornatum sp. nov.
– Scutum mostly tessellate with all punctures separated by much less than one puncture diameter (Fig. 8A); metasoma usually entirely red to orange; if dark brown, then discs of terga not metallic ............................................................................................ L. arenisaltans sp. nov. (in part)
17. Mesepisternum rugose in dorsal half or more, with thin, sparse hair (Fig. 36B); T1 anterior surface shiny (Fig. 95A); ocelli slightly enlarged, separated by much less than 1 ocellar diameter (Fig. 103A) ..................................................................................... L. eophilus (Ellis, 1914) (in part)
– Mesepisternum with crowded punctures but not rugose, with abundant tomentum (Fig. 11B); T1 anterior surface at least weakly coriarious (Fig. 95B); ocelli normal, separated by nearly 1 ocellar diameter (Fig. 103B)......................................................................................... L. argammon sp. nov.
18. Forewing with two submarginal cells (rarely with three in one wing); size very small (body length ~ 3.5 mm; intertegular distance ~ 0.67 mm).......................................................... L. perditum sp. nov.
– Forewing with three submarginal cells; size usually larger (body length ~ 4 mm or more; intertegular distance ~ 0.73 mm or more) ............................................................................................................ 19
19. Metapostnotal rugae usually not reaching posterior margin within 1 or 2 ridge widths (Fig. 104A); scutum often sparsely punctate on both sides of parapsidal lines (i=1–4 pd); dark spiracular spots present on T2–4 (Fig. 105A)............................................................................................................ 20
– Metapostnotal rugae usually uniformly strong and reaching posterior margin (within 1 or 2 ridge widths) (Fig. 104B); scutum usually more densely punctate on either side of parapsidal lines (i ≤ 2 pd); dark spiracular spots usually present on T3–4 only (Fig. 105B).................................... 21
20. Face long (length/width ratio ~0.84) with tomentum much sparser than on gena, surface mostly exposed (Fig. 52C); mesepisternum sometimes becoming areolate dorsally........ L. lilianae sp. nov.
– Face much broader than long (length/width ratio ~0.78) with tomentum as dense as on gena, largely obscuring surface (unless worn) (Fig. 67C); mesepisternum always distinctly punctate throughout................................................................................................ L. pallidellum (Ellis, 1914)
21. Ocellocular area with moderately sparse (i= 1–3 pd), distinct punctures (Fig. 106A); frons, ocellocular area, scutum, and mesepisternum entirely shiny (except small tessellate patch on scutum anteromedially) ................................................................................................................................ 22
– Ocellocular area with dense (i ≤ 1 pd), sometimes obscure punctures (Fig. 106B); frons, ocellocular area, scutum, and/or mesepisternum usually more extensively dull ............................................... 23
22. Scutum with all hairs thickly plumose (Fig. 46B); mesepisternum and hypoepimeron with punctures relatively small and fine (8–9 punctures along scrobal groove) (Fig. 46A) ........... L. julipile sp. nov.
– Scutum with many hairs thin and simple (Fig. 25A); face, mesepisternum, and hypoepimeron with punctures relatively large and coarse (6–7 punctures along scrobal groove) (Fig. 25B) .................... ........................................................................................................................... L. clavicorne sp. nov.
23. T1 and T2 with extensive lateral tomentum (Fig. 1); mesepisternum usually with crowded, indistinct punctures dorsally; pronotal angle usually about 90 degrees (Fig. 107A) .......................................... ....................................................................................... L. hudsoniellum (Cockerell, 1919) (in part)
– T1 and T2 with tomentum absent or limited to thin basal band; mesepisternum usually with distinct, round punctures throughout; pronotal angle obtuse (Fig. 107B)..................................................... 24
24. Metasoma red-orange with the following areas usually brown: basal half of T1, median transverse band on T3, and T4–5 (Fig. 78D); scutum punctures relatively coarse (2–3 punctures present between posterior end of parapsidal line and lateral edge of scutum) .................. L. spivakae sp. nov. (in part)
– Metasoma entirely red-orange; scutum punctures relatively fine (3–5 punctures present between posterior end of parapsidal line and lateral edge of scutum) ........................................................... 25
25. T2–4 with tomentum absent or thin and not well differentiated from surrounding simple hairs (Fig. 28D); scutum hairs usually mostly thin and simple; anteromedial scutum punctures usually finer and less distinct than those elsewhere on scutum (Fig. 28A) ...... L. clematisellum (Cockerell, 1904)
– Distinct tomentum present on T2 basolaterally, T3 basally, and T4 throughout (Fig. 22D); scutum hairs mostly densely plumose; anteromedial scutum punctures usually as distinct as those elsewhere on scutum (Fig. 22A) ...................................................................................... L. clastipedion sp. nov.
26. Mesepisternum rugulose or areolate with punctures absent or crowded and indistinct, at least in part (Fig. 108 A–B).................................................................................................................................. 27
– Mesepisternum smooth with distinctly separated, round punctures throughout (Fig. 108C).......... 33
27. Supraclypeal area tessellate (Fig. 101A); postgena usually dull and lineate (Fig. 102A)............... 28
– Supraclypeal area (Fig. 101B) and postgena (Fig. 102B) mostly smooth and shiny ...................... 29
28. Scutum punctures dense but mostly distinctly separated; face broad (length/width ratio ~0.82); clypeus apical margin black or brown ..................................................... L. pictum (Crawford, 1902)
– Scutum punctures very dense, almost all touching; face long (length/width ratio ~0.85); clypeus apical margin sometimes orange...................................................... L. arenisaltans sp. nov. (in part)
29. Ocelli slightly enlarged (separated by less than two thirds of one ocellar diameter) (Fig. 103A); mesepisternum mostly rugose to rugulose with few or no distinct punctures (Fig. 108A) ............. 30
– Ocelli normal (separated by more than two thirds of one ocellar diameter) (Fig. 103B); mesepisternum usually distinctly punctate at least in ventral half (Fig. 108B) ........................................................ 31
30. T2–4 with extensive dense tomentum on basolateral areas of T2–3 and throughout T4 (Fig. 36D); clypeus apical margin black to reddish brown; legs and metasoma mostly reddish brown ................ ........................................................................................................ L. eophilus (Ellis, 1914) (in part)
– T2–4 with tomentum very sparse or absent (Fig. 38D); clypeus apical margin, legs, and metasoma often extensively orange...................................................................................... L. festinum sp. nov.
31. Pronotal angle usually about 90 degrees (Fig. 107A); dark spiracular spots present on T3–4 only (Fig. 105B); apical impressed areas of T2–3 usually shiny and distinctly punctate; clypeus with weak, obtuse apicolateral denticles (Fig. 3B)................ L. hudsoniellum (Cockerell, 1919) (in part)
– Pronotal angle obtuse (Fig. 107B); dark spiracular spots present on T2–4 (Fig. 105A); apical impressed area of T3 and sometimes T2 coriarious with punctures obscure; clypeus with strong, acute apicolateral denticles (Fig. 3A) .............................................................................................. 32
32. Frons punctures fine and dense but distinctly separated (Fig. 94B); T2–4 usually with extensive dense tomentum on basolateral areas of T2–3 and throughout T4 (Fig. 55C); scutum relatively long (length/width ratio usually ± 0.84) ...................................... L. mesillense (Cockerell, 1898) (in part)
– Frons punctures coarse and crowded (Fig. 94A); T2–4 with sparse tomentum limited to basal margins of T2–3 and basal half of T4 (Fig. 64D); scutum relatively broad (length/width ratio usually ≤ 0.8)................................................................................................................... L. minckleyi sp. nov.
33. Hypoepimeron and upper mesepisternum densely punctate (i <1 pd); surface usually shiny........ 34
– Hypoepimeron and upper mesepisternum relatively sparsely punctate with many punctures separated by 1 puncture diameter or more, or if somewhat dense, then surface entirely imbricate................ 37
34. Dark spiracular spots present on T3–4 only (Fig. 105B); apical impressed areas of T2–3 usually shiny and distinctly punctate ........................................................................................................... 35
– Dark spiracular spots present on T2–4 (Fig. 105A); apical impressed area of T3 and sometimes T2 coriarious with punctures obscure ................................................................................................... 36
35. T2–3 with dense tomentum forming complete lateral and basal bands and apical band on T3 (Fig. 1); pronotal angle about 90 degrees (Fig. 107A); metasoma colour pattern highly variable .......................................................................... L. hudsoniellum (Cockerell, 1919) (in part)
– T2–3 with tomentum absent or limited to sparse lateral patches and apical band on T3 (Fig. 78D); pronotal angle obtuse (Fig. 107B); metasoma red-orange with basal half of T1, median transverse band on T3, and T4–5 usually brown (Fig. 78D) ................................... L. spivakae sp. nov. (in part)
36. Hypoepimeron and upper mesepisternum punctures usually finer, more crowded, and less distinct than lower mesepisternum punctures (Fig. 108B); frons punctures uniformly fine and distinctly separated (Fig. 55D) ............................................................ L. mesillense (Cockerell, 1898) (in part)
– Hypoepimeron and mesepisternum punctures uniformly large and distinctly separated (Fig. 108C); frons punctures larger, becoming crowded medially (Fig. 43B) .................. L. imbriumbrae sp. nov.
37. Pronotal ridge sharply carinate along full height of pronotum (Fig. 109A); scutum and scutellum shiny and very sparsely punctate (i=1–6 pd); metapostnotum mostly shiny with rugae reaching halfway or less to posterior margin.......................................................... L. kunzei (Cockerell, 1898)
– Pronotal ridge absent (Fig. 109B); scutum and scutellum more extensively tessellate and densely punctate (i=1–4 pd); metapostnotum dull with rugae usually reaching more than halfway to posterior margin .............................................................................................................................................. 38
38. Acarinarial fan well-developed with dense appressed hairs, at least laterally (Fig. 95C); postgena usually dull and lineolate throughout (Fig. 102A)........................................................................... 39
– Acarinarial fan weak, with only a few sparse appressed hairs (Figs 95B, 96B); postgena usually smooth and shiny in apical half or more (Fig. 102B)...................................................................... 40
39. Head, mesosoma, and T1 anterior surface mostly shiny; metasomal terga sometimes with metallic green reflections......................................................................................... L. zephyrus (Smith, 1853)
– Head, mesosoma, and T1 anterior surface mostly dull; metasomal terga not metallic ....................... ............................................................................................................................. L. decorum sp. nov.
40. T1 anterior surface coriarious (Fig. 95C); metasomal terga without tomentum (Fig. 13D); pronotal angle obtuse (Fig. 107B)..................................................................................... L. austerum sp. nov.
– T1 anterior surface shiny (Fig. 95A); T2–4 with extensive dense tomentum on basolateral areas of T2–3 and throughout T4 (Fig. 85D); pronotal angle about 90 degrees (Fig. 107A) ........................... ................................................................................................................................ L. torrens sp. nov.
Key to males
1. Tegula enlarged, reaching or nearly reaching scutellum, with inner posterior margin straight or concave, often punctate (Fig. 91A)........................ L. hunteri (Crawford, 1932) and similar species 2
– Tegula ovoid, impunctate, and clearly not reaching scutellum (Fig. 91B)........................................ 2
2. Scutum uniformly densely punctate with all punctures separated by less than 1 puncture diameter (Fig. 110A)......................................................................................................................................... 3
– Scutum with punctures separated by 1 puncture diameter or more, at least submedially (Fig. 110B) ........................................................................................................................................................... 7
3. T1 anterior surface with dense appressed hair (Fig. 111A) (east of Rocky Mountains) ..................... ............................................................................................................... L. vierecki (Crawford, 1904)
– T1 anterior surface with no appressed hair (all hair erect) (Fig. 111B) (Rocky Mountains and westward)........................................................................................................................................... 4
4. Face short (length/width ratio ~0.8); clypeus with broad apical yellow band; hind basitarsus about 5 times as long as broad........................................................................... L. aquilae (Cockerell, 1898) 3
– Face long (length/width ratio ~0.9 or greater); clypeus apical margin black to reddish brown; hind basitarsus less than 4 times as long as broad..................................................................................... 5
5. F2–10 about 1.5 times as long as broad; T1 entirely shiny (mountains of California to British Columbia) .............................................................................................. L. tuolumnense Gibbs, 2009
– F2–10 nearly twice as long as broad; T1 at least faintly coriarious to reticulate (deserts of southern California to Nuevo Leon)................................................................................................................. 6
6. T1–3 coriarious to imbricate with punctures distinct throughout (Fig. 112A) (Baja California to Arizona) .............................................................................................. L. petrellum (Cockerell, 1903)
– T1–3 becoming reticulate with punctures somewhat obscure apically (Fig. 112B) (New Mexico to Nuevo Leon)................................................................................................... L. droegei Gibbs, 2009
7. Clypeus metallic blue-green all the way to the apical rim, sparsely punctate (i=1–5 pd), and with tomentum sparse or absent at least in part (Fig. 113A) ..................................................................... 8
– Clypeus black, brown, or yellow in apical sixth or more, densely punctate (i <1 pd), and/or surface completely obscured by dense tomentum (Fig. 113B) .................................................................... 10
2 L. parvum-tegulare species complex; not treated further herein. Specimens from desert and mountain regions are not likely true L. hunteri.
3 Augochlora -like L. (Dialictus); not treated further herein.
8. T1–6 with abundant tomentum and metallic blue-green at least on base of T1 (Fig. 76D); metasomal sterna with very long hair (2–4 OD); gonostylus very hairy and projecting laterally beyond gonocoxite (Fig. 90M) ....................................................................................................... L. rufornatum sp. nov.
– T1–6 with tomentum sparse or absent and without metallic reflections (Figs 59D, 61D); metasomal sterna with shorter hair (1–2 OD); gonostylus with sparse hair and not reaching lateral edge of gonocoxite (Fig. 90 H–I) .................................................................................................................... 9
9. Rims of T1–3 punctate (Fig. 62D); face with no tomentum; scutum usually mostly shiny and sparsely punctate (Fig. 62A) (i =1–4 pd) (Utah to California) ................................... L. miltolepoides sp. nov.
– Rims of T1–3 impunctate (Fig. 59D); face below eye emargination with sparse tomentum; scutum usually mostly tessellate and very sparsely punctate (i= 1–6 pd) (Fig. 59A) (Yucatan Peninsula)..... ........................................................................................................................... L. meteorum sp. nov.
10. Scutum between parapsidal lines entirely tessellate to finely reticulate and sparsely punctate (Fig. 93A) (i=1–4 pd) (Mexico)................................................................... L. tessellatosum sp. nov.
– Scutum between parapsidal lines shiny and/or densely punctate (i ≤ 1 pd), at least in part (Figs 93C, 110B) (widespread)...........................................................................................................................11
11. T1–4 convex in lateral view, with rims strongly downcurved (Fig. 114A)........ L. cactorum sp. nov.
– T1–4 flat in lateral view (Fig. 114B) ............................................................................................... 12
12. Antennae relatively long (as seen from below, length of F2 about twice length of F1, and F2–11 1.5–2 times as long as broad) (Fig. 115A)....................................................................................... 13
– Antennae relatively short (as seen from below, length of F2 less than twice length of F1, and F2–11 1–1.5 times as long as broad) (Fig. 115B)....................................................................................... 23
13. Clypeus apical half yellow; face short (length/width ratio ~0.81); retrorse lobe very narrow (Fig. 90O) ......................................................................................... L. testaceum (Robertson, 1897)
– Clypeus with apical yellow band absent or, if present, usually much less than half length of clypeus (if one third length of clypeus, then face long (length/width ratio ~0.89)); retrorse lobe broad ..... 14
14. S2–5 with dense plumose hair concentrated on apicolateral portions of S3 and lateral margins of S4–5; hair of S2 thinner and sparser and S4–5 bare apicomedially (Fig. 116A)................................. ................................................................................................................... L. zephyrus (Smith, 1853)
– S2–5 with hairs of uniform density and plumosity throughout (Fig. 116B).................................... 15
15. Clypeus orange to yellow apically (if covered in tomentum, best seen in ventral view); pronotal lobe orange to yellow .............................................................................................................................. 16
– Clypeus black to brown apically (if covered in tomentum, best seen in ventral view); pronotal lobe usually black to brown..................................................................................................................... 18
16. Head ovoid, face long (length/width ratio ~0.89) (Fig. 9C).......................... L. arenisaltans sp. nov.
– Head round, face short (length/width ratio ~0.84–0.86) (Figs 39C, 56B)....................................... 17
17. Face below eye emargination with dense tomentum obscuring the surface underneath (Fig. 56B); rims of T2–3 with distinct punctures in median third or less (Fig. 56D); pronotal collar and metepisternum dark .................................................................................................... L. mesillense (Cockerell, 1898)
– Face below eye emargination with sparse tomentum not obscuring the surface underneath (Fig. 39C); rims of T2–3 distinctly punctate nearly all the way to the lateral edge (Fig. 39D); pronotal collar and metepisternum sometimes with orange patches .................................................. L. festinum sp. nov.
18. Tomentum sparse or absent on clypeus and supraclypeal area; metasoma partially red or metallic green; forewing with three submarginal cells.................................................................................. 19
– Face below eye emargination entirely covered in dense tomentum; metasoma entirely black to brown; forewing sometimes with two submarginal cells ................................................................ 20
19. Propodeum dorsolateral slope rugose; frons, clypeus, and supraclypeal area with at least some tomentum; metasomal terga not metallic (sandy areas east of California).......................................... ................................................................................................... L. pictum (Crawford, 1902) (in part)
– Propodeum dorsolateral slope shiny and distinctly punctate; face with tomentum restricted to lower paraocular area; metasomal terga partially metallic green (especially base of T1) (mountains of California and western Nevada) ..................................................................... L. cembrilacus sp. nov.
20. Head sparsely punctate (frons and paraocular area with i ± 1 pd and ocellocular area with i ± 2 pd) (Fig. 94D); propodeum lateral face usually smooth and tessellate; forewing almost always with two submarginal cells; size small (body length ~ 3.5 mm, intertegular distance ~ 0.65 mm).............................................................................................. L. perditum sp. nov. (in part)
– Head more densely punctate (frons and paraocular area with i ≤ 1 pd and ocellocular area with i ≤ 1.5 pd) (Fig. 94C); propodeum lateral face usually mostly rugulose; forewing often with three submarginal cells; usually larger (body length ~ 4 mm or more, intertegular distance ~ 0.75 mm or more)................................................................................................................................................ 21
21. Scutum and metasomal terga usually with many thin, weakly plumose hairs; T2–3 with no basolateral tomentum (Fig. 117A) ................................................................. L. clematisellum (Cockerell, 1904)
– Scutum and metasomal terga with most hairs thick and densely plumose; T2–3 usually with some basolateral tomentum (but often sparse) (Fig. 117B) ...................................................................... 22
22. Postgena entirely dull and lineolate (Fig. 102A); posterior face of propodeum usually rugulose (Utah and northern Arizona) ..................................................................................... L. clastipedion sp. nov.
– Postgena weakly lineate and usually shiny in part (Fig. 102B); posterior face of propodeum shiny and distinctly punctate (eastern Arizona, New Mexico, and Chihuahua)............................................ .................................................................................................................. L. julipile sp. nov. (in part)
23. Metasomal terga with no tomentum; mesonotum and metasomal terga with most hairs thin and simple or weakly plumose (Fig. 117A)............................................................................................ 24
– Metasomal terga with at least some basolateral tomentum; mesonotum and metasomal terga with most hairs densely plumose and thick (Fig. 117B).......................................................................... 28
24. Propodeum dorsolateral slope rugose........................................ L. pictum (Crawford, 1902) (in part)
– Propodeum dorsolateral slope smooth............................................................................................. 25
25. Mesepisternum and hypoepimeron densely punctate (i<1 pd) ........................................................ 26
– Mesepisternum and hypoepimeron sparsely punctate (i ± 1 pd) ..................................................... 27
26. Propodeum with weak microsculpture, appearing somewhat shiny; rims of T1–3 punctate basally (Fig. 65D); apical margin of clypeus and labrum usually orange ...................... L. minckleyi sp. nov.
– Propodeum with strong dull microsculpture; rims of T1–3 almost completely impunctate (Fig. 44D); apical margin of clypeus and labrum reddish brown ...................... L. imbriumbrae sp. nov. (in part)
27. Rims of T1–3 impunctate (Fig. 32D) (southern Mexico).................................... L. decorum sp. nov.
– Rims of T1–3 punctate, at least basomedially (Fig. 14D) (Baja California peninsula)....................... ............................................................................................................................ L. austerum sp. nov.
28. Pronotal ridge carinate (Fig. 109A); scutum and mesepisternum very finely, sparsely punctate (i=1–6 pd) ............................................................................................... L. kunzei (Cockerell, 1898)
– Pronotal ridge smoothly rounded (Fig. 109B); scutum and/or mesepisternum more densely punctate (i ≤ 2 pd) .......................................................................................................................................... 29
29. Rim of S5 concave (Fig. 116C) ................................................... L. hudsoniellum (Cockerell, 1919)
– Rim of S5 straight (Fig. 116B) ........................................................................................................ 30
30. Antennae clavate (F7–11 about 1.3 times as wide as basal antenna segments) (Fig. 26C)................. ........................................................................................................................... L. clavicorne sp. nov.
– Antennae normal (all segments about equally wide)....................................................................... 31
31. Rims of T1–3 opaque with punctures as dense and distinct as those on discs and covering entire surface (Fig. 79D)................................................................................................. L. spivakae sp. nov.
– Rims of T1–3 usually translucent, punctures finer and sparser than those on discs and/or restricted to basomedial area ............................................................................................................................... 32
32. Wings with membrane lightly infuscated, veins brown, and most hairs dark (Fig. 100B)...................................................................................... L. imbriumbrae sp. nov. (in part)
– Wings with membrane hyaline, veins light brown to amber contrasting with dark brown subcosta, and most hairs light (Fig. 100A)...................................................................................................... 33
33. T1–5 with extensive tomentum; metasoma often partially or entirely orange ................................ 34
– Metasomal terga with tomentum limited to small basolateral patches on T2–4; metasoma all black................................................................................................................................................. 35
34. Face long (length/width ratio ~0.89); clypeus usually sparsely punctate (i =1–4 pd), often with a broad orange apical band (Fig. 52C) ..................................................................... L. lilianae sp. nov.
– Face short (length/width ratio ~0.82); clypeus moderately densely punctate (i=1–2 pd) without orange apical band (Fig. 68C) ................................................................. L. pallidellum (Ellis, 1914)
35. Head sparsely punctate (frons and paraocular area with i ± 1 pd and ocellocular area with i ± 2 pd) (Fig. 94D); propodeum lateral face usually smooth and tessellate; forewing almost always with two submarginal cells; size small (body length ~ 3.5 mm, intertegular distance ~ 0.65 mm).............................................................................................. L. perditum sp. nov. (in part)
– Head more densely punctate (frons and paraocular area with i ≤ 1 pd and ocellocular area with i ≤ 1.5 pd) (Fig. 94C); propodeum lateral face usually mostly rugulose; forewing often with three submarginal cells; slightly larger (body length ~ 4 mm, intertegular distance ~ 0.77 mm).................. .................................................................................................................. L. julipile sp. nov. (in part)
description: Published as part of Gardner, Joel & Gibbs, Jason, 2020, The ' red-tailed' Lasioglossum (Dialictus) (Hymenoptera: Halictidae) of the western Nearctic, pp. 1-242 in European Journal of Taxonomy 725 on pages 222-230, DOI: 10.5852/ejt.2020.725.1167, http://zenodo.org/record/4298139