Lasioglossum (Sphecodogastra) truncatum ( Robertson 1901 )

Gibbs, Jason, Packer, Laurence, Dumesh, Sheila & Danforth, Bryan N., 2013, Revision and reclassification of <i> Lasioglossum </ i> (<i> Evylaeus </ i>), <i> L. </ i> (<i> Hemihalictus </ i>) and <i> L. </ i> (<i> Sphecodogastra </ i>) in eastern North America (Hymenoptera: Apoidea: Halictidae), Zootaxa 3672 (1), pp. 1-116 : 96-116

Lasioglossum (Sphecodogastra) truncatum ( Robertson 1901)

( Figs. 5Q , 43H , 44H , 45I , 46I , 71 , 72 , 76F , 79B , 80B , 86B )

Halictus truncatus Robertson 1901, p. 230

Lectotype. ♀ USA, Illinois, Macoupin Co., Carlinville , 15.vi.1887 (C. A. Robertson) [ INHS: 5076] designated by W. E. LaBerge in Webb 1980. Examined by JG 2011

Halictus fulgidus Crawford 1902, p. 235 (syn. Crawford 1907b)

Syntype. ♀ USA, Nebraska, Lancaster Co., Lincoln , iv [ NMNH]

Evylaeus truncatus (in Mitchell 1960 redescription, key ♀, ♂ misdet. of L. oenotherae ; Knerer & Atwood 1962 description ♂; Hurd 1979: catalogue; Moure & Hurd 1987: catalogue)

Halictus (Evylaeus) truncatus (in Viereck 1916: catalogue)

Lasioglossum (Evylaeus) truncatum (in Michener 1951: catalogue; Krombein 1967: catalogue)

Diagnosis. Female L. truncatum can be recognised by the combination of head wide (L/W ratio = 0.88–0.91) ( Fig. 43H ); metapostnotum coarsely rugose ( Fig. 79B ); and T2 apical impressed area impunctate ( Fig. 80B ). They are most similar to L. cinctipes , but L. truncatum differs in having the ocellocular area polished and distinctly punctate; pronotal dorsolateral angle orthogonal; lateral propodeal carinae subparallel; inner metatibial spur pectinate ( Fig. 5Q ); and T2 apical impressed area impunctate.

Male L. truncatum can be recognised by the combination of clypeus strongly protruding below suborbital tangent ( Fig. 44H ); mesoscutum polished due to lack of microsculpture; T2 apical impressed area sparsely punctate ( Fig. 86B ); metasomal sterna nearly bare, with only very short hairs (<0.5 OD) (as in Fig. 85A ); and retrorse lobe present ( Fig. 46H ). Lasioglossum cinctipes is most similar but differs in head shape, the clypeus barely protruding below suborbital line ( Fig. 44A ); T2 apical impressed area densely punctate ( Fig. 86A ); and retrorse lobe absent ( Fig. 46A ). In the east, the long gonostylus with long plumose setae of the gonostylus ( Fig. 45I ) separates L. truncatum from all others.

Redescription. FEMALE. Length 6.8–9.0 mm. Head length 1.85–2.20 mm. Head width 2.04–2.50 mm. Wing length 5.7–6.8 mm. (n=10)

Colour. Head and mesosoma black. Antenna black, except ventral surface of flagellum brown. Tegula dark reddish brown. Legs dark brown, except medio- and distitarsi reddish brown. Wing membrane hyaline, faintly dusky. Pterostigma testaceous. Metasomal terga black-brown, apical margins pale brown-testaceous.

Structure. Head very wide (L/W ratio = 0.88–0.91). Clypeus 1/2 below suborbital line. Eyes convergent below (UOD:LOD = 1.04–1.14). Gena subequal to eye width. Ocelli normal. Pronotum smoothly rounded. Protibial spur with apical serrations as long as width of malus. Inner metatibial spur pectinate, teeth 3–4, basal teeth longer than width of rachis. Propodeal lateral carinae subparallel, reaching dorsal margin, oblique carina high, separating dorsolateral slope from posterior surface.

Surface sculpture. Supraclypeal area weakly polished, punctures sparse (i=1–2.5d). Gena lineolate, postgena smoother. Mesoscutum polished, weakly imbricate anteromedially; punctures dense laterally (i≤d), well-spaced between parapsidal lines (i=1–2d). Mesepisternum rugose, rugulose ventrally. Metapostnotum coarsely rugose. Propodeum imbricate-tessellate. Metasomal terga polished; punctures dense basally, very sparse apically, T2 apical impressed area broadly impunctate medially.

Pubescence. Head and mesosoma with sparse plumose hairs. Metafemoral scopa with dense plumose hairs. Metasomal terga with relatively sparse, medially-interrupted apical fimbriae. T1 with sparse, erect plumose hairs. T2–T4 with dense basal bands of tomentum, sometimes medially (or entirely on T4) obscured by preceding segment.

MALE. Length 5.9–8.8 mm. Head length 1.55–2.11 mm. Head width 1.63–2.16 mm. Wing length 4.8–6.4 mm. (n=3).

Structure. Head round (L/W ratio = 0.95–1.01). Mandible short, reaching opposing clypeal angle. Flagellomeres, except F1 elongate, F2 longer than F1 and pedicel combined. Eyes strongly convergent below (UOD:LOD = 1.38–1.52). Gena narrower than eye. Pronotum smoothly rounded. Propodeal lateral carina reaching dorsolateral slope, contiguous with strong oblique carina.

Colour. Head and mesosoma black. Clypeus yellow apical half. Mandible brown. Labrum yellow. Antenna black, except ventral surface of flagellum brown. Legs dark brown, except tarsi, bases and apices of tibiae yellow, anterior surface of protibia yellow-testaceous. Wing membrane hyaline. Pterostigma orange-brown. Metasomal terga dark brown, pale brown apically.

Surface sculpture. Supraclypeal area imbricate, punctures dense (i≤d). Gena lineolate. Mesoscutum polished, reticulate anterolaterally; punctures dense laterally (i≤d), well-separated between parapsidal lines (i=1–2d). Mesepisternum rugose. Metapostnotum carinate-rugose. Propodeum rugose. Metasomal terga polished; punctures deep, close basally. T1–T4 apical impressed areas with sparse punctures, T5–T6 impunctate apically.

Pubescence. Head and mesosoma with sparse plumose hairs. Face below eye emargination with dense tomentum, clypeus bare on distal half. Propodeum largely bare, with scattered plumose hairs. Metasomal terga nearly bare, without apical fimbriae. T2–T4 with thick, basolateral patch of tomentum. Metasomal sterna nearly bare, with sparse, short, simple and plumose hairs (≤1 OD).

Terminalia . As shown in Figs. 45I , 46I . Gonostylus long, with elongate, plumose setae. Retrorse lobe long, broad, attenuated apically.

Taxonomic notes. Mitchell (1960) incorrectly associated the male of L. truncatum with L. cinctipes . Knerer discovered the true male of L. truncatum ( Mitchell 1962; Knerer & Atwood 1964). Although L. truncatum is superficially similar to L. cinctipes , the structure of the male genital capsule suggests and molecular phylogenetic study, suggest they are not closely related. Western North American species, such as L. cooleyi ( Crawford 1906c) and L. pullilabre ( Vachal 1904) , belong to the same species group as L. truncatum , sharing an elongate gonostylus with long setae.

Biology. Lasioglossum truncatum is polylectic ( Moure & Hurd 1987). There are no published records of its nesting biology or social level, but it is believed to be a eusocial ground-nester. Examination of specimen records of L. truncatum in the northeastern USA suggests that this species may have become less common in recent decades ( Bartomeus et al. 2013). Nevertheless, the species is still found regularly in recent collections (e. g. Gibbs 2009b; Donovall et al. 2010; Park et al. 2010).

DNA barcodes. Two individuals were sampled (maximum intraspecific p-distance: 0%). The minimum interspecific p-distance separating L. truncatum from other species herein is 9.5%. Seven fixed nucleotide substitutions distinguish L. truncatum from other species included herein: positions 87(T), 127(C), 144(C). 352(G), 399(T), 453(C), and 510(G) (see Table 2).

Range. Fig. 73 .

Material examined. 525 (424 females, 101 males). Deposited in AMNH, ANSP, BBSL, CMNH, CNC, EMEC, MCPM, MCZ, MSUC, PMAE , ROMent, UCMC, and UCRC.

CANADA. ONTARIO: Georgian Bay; Hastings Co.: Marmora; Huron Co.: Kinburn; Lanark Co.: Franktown; Perth; Rideau Ferry; Smith Falls; Leeds-Grenville United Co.; Athens; Chaffeys Lock; Opinicon; Spencerville, Limerick For.; Muskoka Dist.: Dorset; Muskoka; Six Mile Lake, Port Severn, 6 mi. N; National Capital Reg.: Constance Bay; Ottawa; Northumberland Co.: Brighton; QUEBEC: Montérégie Reg.: Knowlton; Mt. St. Hilaire; Outaouais Reg.: Beech Grove; Gatineau Pk., Harrington Lk.; Kirk`s Ferry; Tenaga.

USA. CONNECTICUT: Fairfield Co.: Stamford; Litchfield Co.: Colebrook; Westbury; New Haven Co.: New Haven; ILLINOIS: Cook Co.: Edgebrook; Macoupin Co.: Carlinville; Perry Co.: Pyatts; Winnebago Co.: Rockford; KANSAS: Douglas Co.: Lawrence; Pleasant Grove, 3 mi. SW; MAINE: Piscataquis Co: Greenville; MASSACHUSETTS: Hampden Co.: Chester; Middlesex Co.: Auburndale; Framingham; Holliston; West Newton; Norfolk Co.: Blue Hills; Milton; Needham; Sharon; Suffolk Co.: Forest Hills; Worcester Co.: Petersham; MICHIGAN: Lake Co.; MINNESOTA: Fillmore Co.: Fountain, 3 mi. N; Pine Co.: Lower Tamarack R.; Wabasha Co.: Wabasha, 3 mi. W; MISSOURI: Greene Co.: Willard; Howell Co.: Willow Springs; St. Louis Co.: Tyson Res. Sta., nr. Eureka; NEBRASKA: Cass Co.: South Bend; Lancaster Co.: Lincoln; Malcolm; NEW HAMPSHIRE: Belknap Co.: Meredith; Meredith Ctr.; Cheshire Co.: Nelson; Coos Co.: Gorham; Lancaster; NEW YORK: Albany Co.: Rensselaerville, Huyck Preserve; Broome Co.; Cattaraugus Co.: Cattaraugus; Cayuga Co. : Spring Lake; Madison Co.; Orange Co.; Otsego Co.; Putnam Co.: Garrison; Seneca Co. : Aurora , 2 mi. N; Suffolk Co.: Cold Spring Harbor; Tompkins Co.: Enfield, Teeter Rd.; Freeville; Ithaca; Ithaca, Cornell U.; Ithaca, Van Natta’s Dam; Westchester Co.; NORTH CAROLINA: Alleghany Co.: Scenic Hwy.; Avery Co.: Grandfather Mt.; Burke Co.: Linville; Haywood Co.: Cruso; Hyde Co.; Johnston Co.; Macon Co.: Highlands; Wayah Bald; McDowell Co.: Blue Ridge Pkwy.; Marion; Moore Co.: Southern Pines; Swain Co.: Bryson City; Wake Co.: Raleigh; Washington Co.: Pettigrew S.P.; Wilkes Co.: Moravian Falls; NORTH DAKOTA: Richland Co.: Walcott, 14 mi. SW; OHIO: Athens Co.: New Marshfield; PENNSYLVANIA: Allegheny Co.: Pittsburgh; Beaver Co.: New Galilee; Lehigh Co.: Lehigh Gap; Montgomery Co.: Edge Hill; Somerset Co.; Tioga Co. : Mansfield; Westmoreland Co.; Jeanette; Pleasant Grove, 2 mi. S; Powdermill N.R.; SOUTH CAROLINA: Oconee Co.: Mountain Rest; SOUTH DAKOTA: Lawrence Co.: Fs Rd. 131.1; VERMONT: Caledonia Co. : Burke Mt. S.P.; Bennington Co.; Windham Co.: Westminster; Windsor Co.; VIRGINIA: Shenadoah N.P.; Carroll Co.: Laurel Fork; Fairfax Co.: Dunn Loring; WEST VIRGINIA: Greenbrier Co.: Alvon; Hardy Co.: Lost River S.P.; Pendleton Co.: Spruce Knob; WISCONSIN: Burnett Co.: Fish Trap; Randal; Yellow River; Grant Co.: Boscobel; Wyalusing; Pierce Co.: Prescott; St. Croix Co.: North Hudson; Vernon Co.: Genoa.

DISCUSSION

The new classification proposed herein for the weak-veined Lasioglossum (or Hemihalictus series) is novel and unlikely to be accepted by some authors, including experts on halictid taxonomy who explicitly reject phylogenetic (cladistic) classifications (e. g. Ebmer 2002). The large number of subgeneric changes, including many taxa of importance for research in the fields of sociobiology and social evolution (e. g. L. (Sphecodogastra) albipes ( Fabricius 1781)) , is bound to cause consternation among many biologists working with bees. Nevertheless, we consider the logic and consistency of applying a cladistic classification far superior to other modes of classification (Hennig 1965, 1975) and arguments in favour of naming paraphyletic groups to be largely fallacious (reviewed in Schmidt-Lebuhn 2012). If the arguments for a cladistic classification are accepted, then the subgeneric limits of many Lasioglossum subgenera proposed by previous authors should be rejected on the grounds of demonstrated paraphyly and polyphyly ( Danforth et al. 2003; Gibbs et al. 2012a, b; Fig. 2 ). It is unfortunate that the application to set aside the priority of Sphecodogastra and Hemihalictus was rejected ( Gibbs et al. 2009; ICZN 2011) since this decision has resulted in many more name changes than would have otherwise been required.

The decision to recognise L. ( Hemihalictus ) and L. (Dialictus) based primarily on colour was made expressly for retaining a consistent subgenus for as many species as possible. Some known exceptions to this colour-based classification are as follows. Lasioglossum (Sudila) belongs to the L. ( Hemihalictus ) clade ( Danforth et al. 2003; Gibbs et al. 2012b) but includes some weakly metallic species ( Sakagami et al. 1996). The definition of L. ( Hemihalictus ) must therefore expand to include the traits used to recognise L. ( Sudila ), including the presence of a mesepisternal tubercle and pectinate male inner metatibial spurs. Pectinate inner metatibial spurs are also present in L. (Mediocralictus), considered by previous authors to be a synonym of L. (Dialictus) s. l. (e. g. Michener 2007; Gibbs 2011), but included here in L. ( Hemihalictus ), which highlights the arbitrary nature of maintaining L. ( Sudila ) as distinct. One of the notable features of L. ( Sudila ) is the large headed males, with sabre-like mandibles. Although less extreme, this state is also present in other L. ( Hemihalictus ) species, including a number of Nearctic species such as L. lustrans , the fedorense species-group, and the pectinatum species-group ( Figs. 6 , 84 ), as well as the Old World sexstrigatum species-group ( Pesenko 2007a). The genus-group Afrodialictus Pauly (1984) also contains both dark and metallic forms. This group could be recognised separately until its phylogenetic placement is determined with certainty, but it is likely more closely related to L. (Dialictus) than L. ( Hemihalictus ) (JG, unpublished results). There are also some large, metallic, Neotropical species, such as L. figueresi , historically placed into L. (Dialictus) (e. g. Wcislo 1990; Engel et al. 2007), that are sufficiently different from either L. ( Hemihalictus ) or L. (Dialictus) to warrant separate status ( Danforth et al. 2003; Gibbs et al. 2012b). Some of these metallic Neotropical species are structurally similar to L. ( Eickwortia ) McGinley (1999), which lacks metallic colouration, and may be closely related. There are other Neotropical species, such as L. gattaca Danforth and Wcislo (1999) and L. hartmanni Danforth and Wcislo (1999) , that fall within the metallic L. (Dialictus) clade ( Danforth et al. 2003; Gibbs et al. 2012b) but only have distinct metallic colouration in the male ( Danforth & Wcislo 1999; JG pers. obs.). In the most robust phylogeny of the genus published to date, Gibbs et al. (2012b) recovered L. gattaca as sister to the main clade of metallic Nearctic L. (Dialictus). This clade, including L. gattaca , shares an appressed patch of hairs on metasomal tergum 1 of females, which is apparently a synapomorphy uniting most L. (Dialictus) ( Gibbs 2009b; JG pers. obs.), albeit secondarily lost in a small number of species (e. g. L. microlepoides ( Ellis 1914)) .

The diagnosis of the subgenus L. ( Sphecodogastra ) must now include the subgeneric characters of “carinate Evylaeus ” (see Ebmer 1995). This is unfortunate because L. ( Sphecodogastra ), as originally defined, lack a propodeal carina. However, some species of “carinate Evylaeus ”, such as some members of the L. pauxillum species-group, also have reduced propodeal carinae ( Pesenko 2007a) so it is not new for subgeneric diagnoses to include both states. There are some Palaearctic species of “carinate Evylaeus ” which are also crepuscular, including L. pallidum ( Radoszkowski 1888) , which has enlarged ocelli ( Ebmer 2008). The distinction between L. ( Sphecodogastra ) and a paraphyletic L. ( Evylaeus ) is thus based mainly on the form of the metatibial scopa, which in the Onagraceae specialized L. ( Sphecodogastra ) s. s. is reduced to a single row of simple, apically hooked hairs. A reduced scopa is a derived trait associated with specialization on Onagraceae , and similar modifications can be seen in some other bees that specialize on these plants (Cockerell 1937; LaBerge & Thorpe 2008; Ebmer 2008). Some authors have placed more emphasis on the ocelli when treating L. texanum and L. noctivaga as a distinct subgenus from the other Onagraceae specialists, such as L. oenotherae and L. lusorium , which have been included in L. ( Evylaeus ) ( Hurd 1979; Moure & Hurd 1987); but increased ocellar size is to be expected in more nocturnally active species.

Adjustments to the classification proposed herein will be required as additional phylogenetic information becomes available. A solution to retain many species in L. ( Evylaeus ) is not readily available because L. ( Sphecodogastra ) is nested within the so-called “carinate Evylaeus ” ( Danforth et al. 2003; Gibbs et al. 2012a, b). Since the type species of L. ( Evylaeus ) is L. cinctipes , which is not nested within the L. ( Sphecodogastra ) clade ( Danforth et al. 2003; Gibbs et al. 2012b), retention of this subgenus in a restricted sense is required by the evidence. Should more robust phylogenies place this group as a basal branch of L. ( Sphecodogastra ), then synonymising the two names would be become an option. There is no clear morphological basis for diagnosing L. ( Evylaeus ) separately from L. ( Sphecodogastra ) s. l., when considered globally. Lasioglossum cinctipes is morphologically similar to some species known to be nested within L. ( Sphecodogastra ) s. l., such as the laticeps group ( Pesenko 2007a). Future phylogenetic inferences of Lasioglossum , based upon combined molecular and morphological data, with improved taxon sampling, will hopefully shed light on the relationships of these important taxa and characters useful for their diagnosis.

Alternative strategies to the one above for recognition of monophyletic groups would be to recognise fewer or many more subgenera. All subgenera of weak-veined Lasioglossum could be lumped into one massive subgenus, which would be known as L. ( Hemihalictus ). This would have the advantage of easy diagnosibility but would obscure much of the phylogenetic information contained in a more finely divided classification. Recognition of species-groups within this large genus, however, would partially alleviate this difficulty. Lasioglossum (Hemihalictus) could also be used to include all metallic species, thus being nearly identical to the L. (Dialictus) s. l. used by some authors (e. g. Michener 2007). A disadvantage of both of these classifications would be the increased number of nomenclatural changes, since hundreds more species would undergo subgeneric changes than with the classification proposed above.

Another option would be to recognise many more subgenera, following Warncke (1975) and Pesenko (2007a). An advantage of this strategy would be that L. ( Sphecodogastra ) and L. ( Hemihalictus ) could remain narrowly delimited. However, the monophyly of many of these nominal groups is not well-established and the number of taxa that would change subgenera from standard usage would not be much less than suggested herein. Until a comprehensive phylogeny of Lasioglossum is completed, correct subgeneric placement of many species would be more difficult. A more finely divided classification may be desirable and ultimately may prove necessary, but we believe it would best be applied once more phylogenetic information is available.

A global phylogenetic study of Lasioglossum s. l. is currently in progress that will include a number of problematic taxa (e. g. L. ( Afrodialictus )) hitherto not included in any robust phylogeny. The goal of this project is to help resolve the outstanding taxonomic and nomenclatural problems within Lasioglossum . Once completed, a more stable classification with more carefully circumscribed subgenera may be possible; however, based on available phylogenetic results and unpublished data it is unlikely to prevent the broad application of L. ( Sphecodogastra ) and L. ( Hemihalictus ) to species historically placed in other subgenera. It is expected that the classification for the species treated above, some of which have been included in previous phylogenetic studies, will remain largely unaffected.

KEYS TO SPECIES OF BLACK HEMIHALICTUS SERIES (WEAK-VEINED LASIOGLOSSUM ) IN NORTH AMERICA, EAST OF THE MISSISSIPPI RIVER

Key to sexes

Flagellomeres 10; metasomal terga 6; T5 with distinct prepygidial area; scopa present............................... females Flagellomeres 11; metasomal terga 7; T5 without distinct prepygidial area; scopa absent............................... males

Key to females

1. Metafemoral scopa composed of numerous plumose hairs ( Fig. 74A ); metatibia with ventral hairs not much longer than distal width of tibia ( Fig. 74A ); ocellar diameter shorter than ocellocular distance..................................... 2

- Metafemoral scopa composed of a single row of hairs ( Fig. 74B ); metatibia with ventral hairs much longer (about 2X) than distal width of tibia ( Fig. 74B ); ocellar diameter variable, shorter or longer than ocellocular distance ( Fig. 43H ) ( Sphecodogastra sensu McGinley [2003] ; oligoleges on Onagraceae )................................................. 18

2. Mesoscutum rugose anteriorly, reticulate-punctate between parapsidal lines; lateral and posterior surfaces of propodeum covered with dense appressed hairs, obscuring integument and sharply contrasting against bare metapostnotum ( Fig. 75A )........................................................................................ L. (H.) nelumbonis

- Mesoscutum punctate anteriorly, punctate with clear interspaces between parapsidal lines; lateral and posterior surfaces of propodeum with sparse erect hairs, not obscuring integument or sharply contrasting against metapostnotum ( Fig. 75B, 75C )................................................................................................... 3

3. Mesepisternum entirely coarsely rugose, including region adjacent to mesocoxa ( Fig. 76C )............ L. (H.) pectorale

- Mesepisternum rugulose or punctate, at least in part, never coarsely rugose in region adjacent to mesocoxa ( Figs. 76A, 76B, 76D–F ) (if mesepisternum moderately rugose then head wide: L/W ratio = 0.83–0.93)............................ 4

4. Pronotum with sharply angled dorsolateral ridge (metasoma colour variable; reddish orange to black-brown).......... 5

- Pronotum smoothly rounded, without sharply angled lateral ridge (metasoma colour black-brown)................... 8

5. Metatibial inner spur with approximately 15–20 teeth, teeth not much longer than wide ( Fig. 5H ); supraclypeal area sparsely punctate (i=1–2d), punctures similar in size to clypeal punctures ( Fig. 4H )......................... L. (H.) pectinatum

- Metatibial inner spur with 4 to 5 teeth, at least basal tooth much longer than wide ( Figs. 5B, 5J, 5K ); supraclypeal area densely punctate (i<d), punctures much smaller in size than clypeal punctures ( Figs. 4B, 4J, 4K ).................... 6

6. Metapostnotum coarsely rugose ( Fig. 77A ); mesoscutum polished, shiny............................ L. (H.) sopinci

- Metapostnotum rugulose, posterior margin imbricate ( Fig. 77B, 77C ); mesoscutum dull........................... 7

7. Hypoepimeral area punctate ( Fig. 78A ); dorsolateral ridge of pronotum with carina ending posterior of oblique sulcus............................................................................................. L. (H.) swenki

- Hypoepimeral area impunctate ( Fig. 78B ); dorsolateral ridge of pronotum with carina extending anterior of oblique sulcus....................................................................................... L. (H.) fedorense

8 (4). Mesepisternum punctate (as in Fig. 76B ) (size small, length 4.8–6.6 mm; T2 and T3 with basolateral patches of tomentum)................................................................................................... 9

- Mesepisternum rugulose to rugose (as in Figs. 76A, 76C, 76F ) (size and metasomal terga pubescence variable)....... 10

9. Head short (L/W ratio = 0.94–0.99) ( Fig. 4A )................................................ L. (H.) birkmanni

- Head long (L/W ratio = 1.02–1.09) ( Fig. 4F )............................................. L. (H.) macoupinense

10 (8). Metapostnotum coarsely rugose ( Figs. 79A, 79B ); head wide (L/W ratio = 0.83–0.93) ( Figs. 43A, 43I ).............. 11

- Metapostnotum rugulose ( Figs. 79 C-79F, 82A-82C); head usually longer (L/W ratio> 0.92) ( Figs. 4C, 4E, 4F , 43B, 43C, 43F, 43G )........................................................................................ 12

11. T2 apical impressed area punctate; propodeal lateral carinae divergent dorsally; ocellocular area finely rugulose, punctures indistinct; inner metatibial spur denticulate, teeth shorter than width of rachis ( Fig. 5M ); pronotum dorsolateral angle obtuse....................................................................................... L. (E.) cinctipes

- T2 apical impressed area impunctate; propodeal lateral carinae subparallel dorsally; ocellocular area polished, punctures distinct; inner metatibial spur pectinate, teeth longer than width of rachis ( Fig. 5Q ); pronotum dorsolateral angle orthogonal........................................................................................ L. (S.) truncatum

12 (10). Propodeum “carinate”: lateral carina reaching dorsal surface, lateral and posterior surfaces completely separated by carina ( Figs. 75B , 79 C-79F)............................................................................... 13

- Propodeum “carinaless”: lateral carina reaching about halfway to dorsal surface, lateral and posterior surfaces not separated by carina dorsally ( Figs. 75C , 82 )..................................................................... 16

13. Head long (L/W ratio> 1.00) ( Figs. 43F, 43G ); inner metatibial spur with basal teeth longer than width of rachis ( Figs. 5O, 5P ); T1 dull due to fine microsculpture................................................................. 14

- Head shorter (L/W ratio <1.00) ( Figs. 43B, 43C ); inner metatibial spur with basal teeth shorter than width of rachis ( Figs. 5M, 5N )); T1 shiny due to lack of microsculpture........................................................ 15

14. Metasomal terga usually with comparatively dense apicolateral fimbriae ( Fig. 81C ); head long (L/W ratio = 1.00–1.03); inner metatibial spur with basal teeth much longer than width of rachis (body size usually larger: 6.5–7 mm) … L. (S.) quebecense

- Metasomal terga with sparse apicolateral fimbriae ( Fig. 81D ); head longer (L/W ratio> 1.04); inner metatibial spur with basal teeth only slightly longer than width of rachis (body size usually smaller: 5.8–6.5 mm)............. L. (S.) seillean

15 (13). Head width subequal to length (L/W ratio = 0.98–1.00) ( Fig. 43B ); propodeum with oblique carina very fine, obscure ( Fig. 79C ).................................................................................... L. (S.) boreale

- Head width greater than length (L/W ratio = 0.93–0.96) ( Fig. 43C ); propodeum with oblique carina coarse, distinct ( Fig. 79D ).............................................................................. L. (S.) comagenense

16 (12). Inner metatibial spur serrate ( Fig. 5E ); T1 with subappressed hairs ( Fig. 82A ) (Submarginal cells usually two; Fig. 1B )........................................................................................... L. (H.) lustrans

- Inner metatibial spur pectinate ( Figs. 5C, 5D ); T1 without subappressed hairs ( Figs. 82B, 82C ) (Submarginal cells three; Fig. 1A )............................................................................................. 17

17. Metapostnotum with rugae not reaching posterior margin, posterior margin smoothly rounded onto posterior propodeal surface ( Fig. 82B )............................................................................ L. (H.) foxii

- Metapostnotum with rugae extending to posterior margin, posterior margin sharply edged ( Fig. 82C )... L. (H.) inconditum

18 (1). Metasomal terga reddish to pale orange ( Fig. 50 ); ocellar diameter greater than ocellocular distance ( Fig. 43H ).................................................................................................. L. (S.) texanum

- Metasomal terga black-brown to black; ocellar diameter less than ocellocular distance ( Figs. 43D, 43E )............. 19

19. Metapostnotum rugose ( Fig. 83A ); propodeum “carinate”: lateral carina coarse, reaching dorsal margin ( Fig. 83A )............................................................................................. L. (S.) oenotherae

- Metapostnotum rugulose ( Fig. 83B ); propodeum “acarinate”: lateral carina fine, not reaching dorsal margin ( Fig. 83B ) (Midwestern species, only known from one individual east of Mississippi River).......................... L. (S.) lusorium

Key to males (It is recommended that males have the terminalia extruded so that the gonostylus and retrorse lobe are visible).

1. Mandible elongate, extending well beyond opposing clypeal angle, nearly reaching opposing mandibular base ( Figs. 84A, 84B ); pronotal dorsolateral ridge sharply angled at least in part............................................... 2

- Mandible shorter, not reaching opposing clypeal angle or only slightly extending beyond it ( Fig. 84C ); pronotal dorsolateral ridge smoothly rounded.............................................................................. 6

2. Clypeus entirely black (Figa. 6E, 84B); submarginal cells usually two ( Fig. 1B )...................... L. (H.) lustrans

- Clypeus yellow, in part ( Figs. 6B, 6H, 6J, 6K , 84A ); submarginal cells three ( Fig. 1A )............................. 3

3. Clypeus black-brown with yellow distal band ( Fig. 6H ); mesoscutal punctation relatively sparse, interspaces laterad to parapsidal line approximately 2–3 puncture diameters; metasomal sterna with long hairs (1.5–2.5 OD)... L. (H.) pectinatum

- Clypeus yellow with brown basolateral patches ( Figs. 6B, 6J, 6K , 84A ); mesoscutal punctation relatively dense, interspaces laterad to parapsidal line approximately 1 puncture diameter; metasomal sterna with short hairs (1–1.5 OD)........... 4

4. Metapostnotum with coarse rugae, posterior margin sharply angled (as in Fig. 77A ) (Eastern)............ L. (H.) sopinci

- Metapostnotum with fine rugae, posterior margin smoothly rounded (as in Figs. 77B, 77C ) (Midwestern)............. 5

5. Gena width subequal to eye, widest point below midlength of eye, towards mandible ( Fig. 16 ); mesepisternum mostly impunctate (as in Fig. 78B )............................................................... L. (H.) fedorense

- Gena narrower than eye, widest point near midlength of eye; mesepisternum finely punctate (as in Fig. 78A ) L. (H.) swenki

6 (1). Flagellomeres 2–10 short, length at most subequal to width; clypeus entirely black ( Fig. 6G, 6I ) (mesepisternum coarsely rugose, Figs. 28 , 34 , 76A )............................................................................ 7

- Flagellomeres 2–10 long, length usually 1.5 to 2 times width; clypeus yellow distally............................. 8

7. Mesoscutum rugose anteriorly; propodeum with sparse tomentum.............................. L. (H.) nelumbonis

- Mesoscutum punctate anteriorly; propodeum with erect hairs only................................ L. (H.) pectorale

8 (6). Metasomal sterna with short hairs (<2 OD) ( Fig. 85A ), if longer (2—2.5 OD), then erect; S6 without medial, longitudinal elevation ( Fig. 85A )................................................................................. 9

- Metasomal sterna with long (2–2.5 OD) posteriorly directed hairs ( Fig. 85B ); S6 with medial, narrow, longitudinal elevation ( Fig. 85B ) ( Sphecodogastra s. s.)..................................................................... 18

9. Mesepisternum smooth, with distinct punctures (as in Fig. 76B )............................................. 10

- Mesepisternum rugulose to rugose, without distinct punctures (as in Figs. 76A, 76D )............................ 11

10. Head shorter (L/W ratio = 0.95–1.00) ( Fig. 6A ); supraclypeal area with close punctures (i≤d).......... L. (H.) birkmanni

- Head long (L/W ratio = 1.06–1.09) ( Fig. 6F ); supraclypeal area with sparse punctures (i=1–2d)..... L. (H.) macoupinense

11(9). Metasomal sterna with relatively long erect hairs (1.5–2.5 OD); propodeum “carinaless” with posterior and lateral surfaces only separated ventrally by weak carina ( Figs. 82B, 82C ); metabasitarsus usually brown, uncommonly yellowish ( Figs. 19 , 22 ) ............................................................................................. 12

- Metasomal sterna with relatively short erect hairs (≤ 1.5 OD) ( Fig. 85A ); propodeum “carinate” with posterior and lateral surfaces completely separated by distinct carina ( Fig. 79 ); metabasitarsus yellow (e. g. Figs. 48 , 54 ).................... 13

12. Metapostnotal rugae not reaching posterior margin ( Fig. 82B )........................................ L. (H.) foxii

- Metapostnotal rugae reaching posterior margin ( Fig. 82C )..................................... L. (H.) inconditum

13(11). Mesoscutum polished; head wide to round (L/W ratio =0.87–1.01) ( Figs. 44A, 44I ).............................. 14

- Mesoscutum dull due to microsculpture; head usually longer (L/W ratio = 1.01–1.08) ( Figs. 44B, 44C, 44F, 44G )..... 15

14. Head wider (L/W ratio = 0.87–0.93), clypeus only weakly protruding below suborbital tangent ( Fig. 44A ); T2 apical impressed area with relatively dense punctation, similar to basal area of tergum ( Fig. 86A ); gonostylus short, with short setae ( Fig. 45A ); retrorse lobe absent ( Fig. 46A ).................................................... L. (E.) cinctipes

- Head longer (L/W ratio = 0.95–1.01), clypeus more strongly protruding below suborbital tangent ( Fig. 44I ); T2 apical impressed area with irregular punctation, sparser than basal area of tergum ( Fig. 86B ); gonostylus long, with long, plumose setae ( Fig. 45I ); retrorse lobe present ( Fig. 46I )............................................... L. (S.) truncatum

15(13). Retrorse lobe strongly recurved at apex ( Fig. 87B ); head usually shorter (L/W ratio = 1.01–1.04) ( Fig. 44C ); S2 punctures fine, sparse (i=1–4d) ( Fig. 88A )........................................................ L. (S.) comagenense

- Retrorse lobe not recurved at apex ( Figs. 87A, 87C, 87D ); head usually longer (L/W ratio = 1.04–1.10) ( Figs. 44B, 44F, 44G ); S2 punctures variable ( Fig. 88 ).................................................................. 16

16. Mesoscutum usually completely reticulate, lacking interspaces between punctures; retrorse lobe longer than gonostylus, apex strongly attenuated, narrow ( Fig. 87C ); S2 punctures fine (as in Fig. 88A )......................... L. (S.) quebecense

- Mesoscutum medially punctate, with small but distinct interspaces between punctures; retrorse lobe either subequal in length to gonostylus ( Fig. 87A ) or much longer but with rounded apex ( Fig. 87F ); S2 punctures variable.................. 17

17. Retrorse lobe short, about as long as gonostylus ( Fig. 87A ); metatibia basally with large yellow patch, longer than width of tibia; S2 punctures distinct, denser (i=1–1.5d) ( Fig. 88B ).......................................... L. (S.) boreale

- Retrorse lobe long, much longer than gonostylus ( Fig. 87D ); metatibia basally brown or with small yellow spot, shorter than width of tibia; S2 punctures obscure, sparser (i = 1–5d) (as in Fig. 88A ).............................. L. (S.) seillean

18 (8). Metasomal terga ferruginous/testaceous ( Fig. 51 ); ocellar diameter greater than ocellocular distance ( Fig. 44H )................................................................................................. L. (S.) texanum

- Metasomal terga black-brown to black ( Figs. 60 , 63 ); ocellar diameter less than ocellocular distance................ 19

19. Metapostnotum rugose (as in Fig. 83A ); propodeum “carinate”, with posterior and lateral surfaces completely separated by distinct carina......................................................................... L. (S.) oenotherae

- Metapostnotum rugulose (as in Fig. 83B ); propodeum “carinaless”, with posterior and lateral surfaces only separated ventrally by weak carina (Western species, only know from one individual east of Mississippi River)........ L. (S.) lusorium

ACKNOWLEDGEMENTS

We would like to thank the following people for providing loans or gifts of material for study. Chris Dietrich and Dmitry Dmitriev (INHS) for facilitating the transfer of Evylaeus loan material to JG. The curators and collection managers of the many institutions listed above for loans of material. In particular, Brian Harris and Seán Brady (NMNH), Manuela Vizek (Naturhistorisches Museum Wien), and Jason Weintraub (ANSP) for arranging loans of type material. We thank Jack Neff (CTMI) and Mike Arduser (Missouri Department of Conservation) for providing specimens of L. fedorense . We are grateful to T’ai Roulston for providing specimens of L. pectinatum and for discussions with JG on the likely host-plant preferences of that species. Sam Droege ( United States Geological Survey) provided numerous specimens from across the eastern United States that were invaluable for DNA barcoding studies (retained at PCYU). Shannon Hedtke (Cornell University) assisted in collecting of L. pectinatum from Physalis plants in New York State.

We would also like to thank Ron McGinley for discussing revisionary studies of Evylaeus with JG and for encouraging this study.

We appreciate funding for travel from the Bradley Endowment at Cornell University (overseen by J. Liebherr, CUIC), which initiated this research and made examination of most material possible. DNA barcoding was supported through funding to the Canadian Barcode of Life Network from Genome Canada, NSERC, and other sponsors listed at www.BOLNET.ca.

JG was supported through funding from the Bradley Endowment and the Digital Bee Collections Network (NSF-BRI #0956388: J. S. Ascher (AMNH) PI, D. Yanega (UCRC), J. G. Rozen (AMNH), Co-PIs). Earlier research on these bees by LP was funded by the Natural Sciences and Engineering Research Council of Canada. Contributions by SD were made possible by funds from NSERC-CANPOLIN. This paper represents contribution #70 from the Canadian Pollination Initiative.

Images were taken using a Visionary Digital BK Plus imaging system using a Canon EOS 40D digital SLR camera housed at PCYU. This imaging system was purchased with funds from the Canadian Foundation for Innovation and the Ontario Research Fund through Canadensys.

We thank two reviewers, Doug Yanega and Sam Droege, and the associate editor, Claus Rasmussen, for comments which improved the accuracy and quality of the manuscript.

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Figures

FIGURE 1. Forewings of female Lasioglossum with arrows indicating weak distal veins. (A) Individual with three submarginal cells. (B) Individual with two submarginal cells. Basal vein (b), pterostigma (pt). Numbers indicate submarginal cells. Modified from Gibbs (2010a).

FIGURE 2. Inferred phylogeny of the Hemihalictus series of Lasioglossum based on 1 mitochondrial and 3 nuclear genes partitioned by genome and codon position and analysed using a mixed evolutionary model and Bayesian methods (modified from Gibbs et al. 2012b). Species included in our revision are denoted with black branches in the tree. Colour-coded bars represent subgenera (see legend). From left to right each column represents a different proposed classification: Michener (2007), Ebmer (2002) and our revised cladistic classification. Since Michener and Ebmer do not discuss each species or taxon included in our phylogeny some subgenera are left blank. The columns do not necessarily represent the opinions of those authors, but are based on our understanding of standard usage, which largely follows their proposed classifications.

FIGURE 4. Faces of female Lasioglossum subgenus Hemihalictus in frontal view. (A) L. birkmanni. (B) L. fedorense. (C) L. foxii. (D) L. inconditum. (E) L. lustrans. (F) L. macoupinense. (G) L. nelumbonis. (H) L. pectinatum. (I) L. pectorale. (J) L. sopinci. (K) L. swenki. Scale bar = 1 mm.

FIGURE 5. Drawings of inner metatibial spurs of female Lasioglossum subgenera Hemihalictus (A-K), Evylaeus (L), and Sphecodogastra (M-Q). (A) L. birkmanni. (B) L. fedorense. (C) L. foxii. (D) L. inconditum. (E) L. lustrans. (F) L. macoupinense. (G) L. nelumbonis. (H) L. pectinatum. (I) L. pectorale. (J) L. sopinci. (K) L. swenki. (L) L. cinctipes. (M) L. boreale. (N) L. comagenense. (O) L. quebecense. (P) L. seillean. (Q) L. truncatum. See McGinley (2003) figures 61, 62, and 65 for images of inner metatibial spurs of L. lusorium, L. oenotherae, and L. texanum.

FIGURE 6. Faces of male Lasioglossum subgenus Hemihalictus in frontal view. (A) L. birkmanni. (B) L. fedorense. (C) L. foxii. (D) L. inconditum. (E) L. lustrans. (F) L. macoupinense. (G) L. nelumbonis. (H) L. pectinatum. (I) L. pectorale. (J) L. sopinci. (K) L. swenki. Scale bar = 1 mm.

FIGURE 16. Lateral habitus of male Lasioglossum (Hemihalictus) fedorense (Crawford). Scale bar = 1 mm.

FIGURE 19. Lateral habitus of male Lasioglossum (Hemihalictus) foxii (Robertson). Scale bar = 1 mm.

FIGURE 22. Lateral habitus of male Lasioglossum (Hemihalictus) inconditum (Cockerell). Scale bar = 1 mm.

FIGURE 28. Lateral habitus of male Lasioglossum (Hemihalictus) nelumbonis (Robertson). Scale bar = 1 mm.

FIGURE 34. Lateral habitus of male Lasioglossum (Hemihalictus) pectorale (Smith). Scale bar = 1 mm.

FIGURE 43. Faces of female Lasioglossum subgenera Evylaeus (A) and Sphecodogastra (B-I) in frontal view. (A) L. cinctipes. (B) L. boreale. (C) L. comagenense. (D) L. lusorium. (E) L. oenotherae. (F) L. quebecense. (G) L. seillean. (H) L. texanum (I) L. truncatum. Scale bar = 1 mm.

FIGURE 44. Faces of male Lasioglossum subgenus Evylaeus (A) and Sphecodogastra (B-I) in frontal view. (A) L. cinctipes. (B) L. boreale. (C) L. comagenense. (D) L. lusorium. (E) L. oenotherae. (F) L. quebecense. (G) L. seillean. (H) L. texanum (I) L. truncatum. Scale bar = 1 mm.

FIGURE 45. Genital capsules of male Lasioglossum subgenera Evylaeus (A) and Sphecodogastra (B-I) in dorsal view. (A) L. cinctipes. (B) L. boreale. (C) L. comagenense. (D) L. lusorium. (E) L. oenotherae. (F) L. quebecense. (G) L. seillean. (H) L. texanum (I) L. truncatum. Scale bar = 1 mm.

FIGURE 46. Genital capsules of male Lasioglossum subgenus Evylaeus (A) and Sphecodogastra (B-I) in ventral view. (A) L. cinctipes. (B) L. boreale. (C) L. comagenense. (D) L. lusorium. (E) L. oenotherae. (F) L. quebecense. (G) L. seillean. (H) L. texanum (I) L. truncatum. Scale bar = 1 mm.

FIGURE 48. Lateral habitus of male Lasioglossum (Evylaeus) cinctipes (Provancher). Scale bar = 1 mm.

FIGURE 50. Lateral habitus of female Lasioglossum (Sphecodogastra) texanum (Cresson). Scale bar = 1 mm.

FIGURE 51. Lateral habitus of male Lasioglossum (Sphecodogastra) texanum (Cresson). Scale bar = 1 mm.

FIGURE 54. Lateral habitus of male Lasioglossum (Sphecodogastra) boreale (Svensson, Ebmer & Sakagami). Scale bar = 1 mm.

FIGURE 60. Lateral habitus of male Lasioglossum (Sphecodogastra) lusorium (Cresson). Scale bar = 1 mm.

FIGURE 63. Lateral habitus of male Lasioglossum (Sphecodogastra) oenotherae (Stevens). Scale bar = 1 mm.

FIGURE 71. Lateral habitus of female Lasioglossum (Sphecodogastra) truncatum (Robertson). Scale bar = 1 mm.

FIGURE 72. Lateral habitus of male Lasioglossum (Sphecodogastra) truncatum (Robertson). Scale bar = 1 mm.

FIGURE 73. Distribution map of Lasioglossum (Sphecodogastra) truncatum (Robertson). Heat map indicates predicted suitable range based on maximum entropy niche-modelling. Black circles indicate actual geo-referenced specimen records.

FIGURE 74. Scopa of hind leg. (A) L. boreale—unmodified scopa. (B) L. oenotherae—modified scopa for Onagraceae pollen collection.

FIGURE 75. Propodeum and metapostnotum of female Lasioglossum. (A) L. nelumbonis showing appressed hairs. (B) L. quebecense showing strong propodeal carinae. (C) L. foxii showing weak-absent propodeal carinae.

FIGURE 76. Mesepisternum of female Lasioglossum. (A) L. inconditum showing weak, rugulose sculpture. (B) L. pectinatum showing punctation. (C) L. pectorale showing coarse, rugose sculpture throughout. (D) L. comagenense showing weak, rugulose sculpture. (E) L. lusorium showing appressed pubescense. (F) L. truncatum showing rugose sculpture becoming rugulose anterior to mesocoxa.

FIGURE 77. Propodeum and metapostnotum of female Lasioglossum (Hemihalictus) of the fedorense species-group. (A) L. sopinci showing coarse sculpture. (B) L. fedorense showing fine sculpture. (C) L. swenki showing fine sculpture.

FIGURE 78. Mesepisternum of female Lasioglossum (Hemihalictus) of the fedorense species-group. (A) L. swenki showing finely punctate surface. (B) L. fedorense showing impunctate surface.

FIGURE 79. Propodeum and metapostnotum of female Lasioglossum (Evylaeus) and L. (Sphecodogastra). (A) L. cinctipes showing coarse, rugose sculpture. (B) L. truncatum showing coarse, rugose sculpture. (C) L. boreale showing fine sculpture and weak propodeal carinae. (D) L. comagenense showing fine sculpture and distinct propodeal carinae. (E) L. quebecense showing fine sculpture and distinct propodeal carinae. (F) L. seillean showing fine sculpture and distinct propodeal carinae.

FIGURE 80. Metasomal terga of female Lasioglossum. (A) L. cinctipes showing finely punctate apical impressed areas. (B) L. truncatum showing impunctate apical impressed areas.

FIGURE 81. Metasomal terga of female Lasioglossum (Sphecodogastra) in the fulvicorne-fratellum species-group. (A) L. boreale. (B) L. comagenense. (C) L. quebecense showing distinct apicolateral fimbriae. (D) L. seillean.

FIGURE 82. Propodeum, metapostnotum and anterior surface of T1 of female Lasioglossum (Hemihalictus). (A) L. lustrans showing fine metapostnotal sculpture and subappressed hairs on T1. (B) L. foxii showing metapostnotal rugae not reaching posterior dorsal margin. (C) L. inconditum showing metapostnotal rugae reaching posterior dorsal margin.

FIGURE 83. Propodeum and metapostnotum of female Lasioglossum (Sphecodogastra) in the Onagraceae specialist lusorium species-group. (A) L. oenotherae showing coarse sculpture and strong carinae. (B) L. lusorium showing fine sculpture and weak carinae.

FIGURE 84. Clypeus and mandible of male Lasioglossum (Hemihalictus). (A) L. sopinci showing large clypeal maculation and elongate mandible. (B) L. lustrans showing entirely black clypeus and elongate mandible. (C) L. inconditum showing narrow, distal, clypeal maculation and short mandible.

FIGURE 85. Metasomal sterna of male Lasioglossum (Spheocodagastra) with arrows indicating pubescence and S6 medial area. (A) L. boreale showing short, sparse hairs and normal S6. (B) L. oenotherae showing long, dense hairs and concave S6.

FIGURE 86. Metasomal terga of male Lasioglossum (Sphecodogastra). (A) L. cinctipes showing numerous punctures on apical impressed areas. (B) L. trunctatum showing few punctures on apical impressed areas.

FIGURE 87. Lateral view of gonostylus and retrorse lobe of Lasioglossum (Sphecodogastra) in the fulvicorne-fratellum species-group. (A) L. boreale. (B) L. comagenense. (C) L. quebecense. (D) L. seillean. Ventral view of retrorse lobe. (E) L. quebecense. (F) L. seillean. Arrows indicate apex of retrorse lobe.

FIGURE 88. False colour image of metasomal sterna of Lasioglossum (Sphecodogastra) in the fulvicorne-fratellum speciesgroup. (A) L. comagenense showing few distinct punctures. (B) L. boreale showing many distinct punctures.