Lasioglossum (Sphecodogastra) boreale Svensson, Ebmer, and Sakagami 1977

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 : 77-80

Lasioglossum (Sphecodogastra) boreale Svensson, Ebmer, and Sakagami 1977

( Figs. 5M , 43B , 44B , 45B , 46B , 53 , 54 , 79C , 81A , 85A , 87A , 88B )

Lasioglossum (Evylaeus) boreale Svensson et al. 1977, p. 219 ♂ Holotype. ♂ Sweden, Torne Lappmark , Abisko, 3.viii.1973 (B. G. Svensson) on Chamaenerion angustifolium [ZMU].

Evylaeus borealis (in Sakagami & Toda 1986. first record for Nearctic region)

Evylaeus (Fratevylaeus) borealis (in Pesenko 2007a: subgeneric classification)

Lasioglossum (Evylaeus) boreale (in Murao & Tadauchi 2007: redescription ♀ ♂)

Diagnosis. Female L. boreale can be recognised by the combination of head round (L/W ratio = 0.98–1.00) ( Fig. 43B ); mesepisternum finely rugulose (as in Fig. 76D ); inner metatibial spur pectinate-denticulate, teeth shorter than width of rachis ( Fig. 5M ); propodeum with lateral carina fine, often not extending to dorsal margin, oblique carina fine (these carinae often so weak as to be difficult to discern) ( Fig. 79C ); and T1 polished due to lack of microsculpture ( Fig. 81A ). In the east, L. boreale is most similar to L. quebecense , L. comagenense , and L. seillean , all of which have strong, well-defined propodeal carinae ( Figs. 79 D-F). Lasioglossum quebecense and L. seillean both have long teeth on the inner metatibial spur, distinctly exceeding the width of the rachis ( Figs. 5O, 5P ) and T1 dull due to microsculpture. The female of L. comagenense has a shorter head (L/W ratio = 0.93–0.96) ( Fig. 43C ).

Male L. boreale can be recognised by the combination of clypeus with yellow on distal half ( Fig. 44B ); mandible short, not extending much beyond opposing clypeal angle; metasomal sterna nearly bare, hairs present but very short ( Fig. 85A ); S2–S3 with dense punctures ( Fig. 88B ); and basitarsi bright yellow ( Fig. 54 ). The unique shape of the retrorse lobe ( Figs. 46B ; 87A ), which is short, subequal in length to gonostylus, is the most reliable character for distinguishing L. boreale males from those of L. comagenense , L. quebecense , and L. seillean ( Figs. 87B, 87C, 87D ). The dense sternal punctures should also distinguish it from these three species ( Fig. 88 ).

Redescription. FEMALE. Length 5.9–6.4 mm. Head length 1.72–1.79 mm. Head width 1.72–1.80 mm. Wing length 4.9–5.2 mm. (n=4)

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

Structure. Head round (L/W ratio = 0.98–1.00). Clypeus ¾ below suborbital line. Eyes convergent below (UOD:LOD = 1.07–1.13). 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 4–6, basal teeth shorter than width of rachis. Propodeal lateral carina reaching dorsal margin, oblique carina low, sometimes obscure, separating dorsolateral slope from posterior surface.

Surface sculpture. Supraclypeal area polished medially, punctures sparse (i=1–1.5d). Gena lineolate, postgena smoother. Mesoscutum imbricate; punctures dense (i≤d), except posteromedially (i=1–1.5d). Mesepisternum finely rugulose, smoother ventrally. Metapostnotum carinate-rugose. Propodeum imbricate-tessellate. Metasomal terga mostly coriarious, T1 polished; punctures dense, sparser posteromedially, T2 apical impressed area impunctate medially.

Pubescence. Head and mesosoma with sparse plumose hairs. Metafemoral scopa with dense plumose hairs. Metasomal terga with relatively dense, medially-interrupted apical fimbriae. T1 with sparse, erect plumose hairs. T2–T4 basolaterally with sparse, tomentum.

MALE. Length 6.7–7.5 mm. Head length 1.82–1.98 mm. Head width 1.69–1.90 mm. Wing length 4.5–5.2 mm. (n=4)

Colour. Head and mesosoma black. Clypeus yellow on apical half. Mandible brown. Labrum yellow, at least basally. Antenna black, except ventral surface of flagellum orange, less so on F10–F11. Legs dark brown, except tarsi, bases and apices of tibiae yellow, anterior surface of protibia yellow-testaceous. Wing membrane hyaline. Pterostigma brown. Metasomal terga dark brown.

Structure. Head long (L/W ratio = 1.04–1.10). Clypeus ¾ below suborbital line. Mandible short, reaching opposing clypeal angle. Flagellomeres, except F1 elongate, F2 longer than F1 and pedicel combined, subequal to scape. Eyes convergent below (UOD:LOD = 1.34–1.39). Gena narrower than eye. Pronotum smoothly rounded. Propodeal lateral carina nearly reaching dorsolateral slope.

Surface sculpture. Supraclypeal area imbricate, with sparse, shallow punctures (i=1–1.5d). Gena lineolate. Mesoscutum imbricate, reticulate anterolaterally; punctures dense (i≤d) but clearly separated medially (i=1–1.5d). Mesepisternum rugulose, weakly so ventrally. Metapostnotum anastomosingly rugose. Propodeum rugulose, posterior surface rugose. Metasomal terga polished; punctures deep, close basally. T2–T6 apical impressed areas impunctate. Metasomal sterna with distinct, deep punctures (i=1–1.5d).

Pubescence. Head and mesosoma with sparse plumose hairs. Face below antennal sockets with dense tomentum, clypeus bare on distal half. Propodeum largely bare, with scattered plumose hairs. Metasomal terga nearly bare, without apical fimbriae. T2 with narrow, basolateral patch of tomentum. Metasomal sterna nearly bare, with sparse, short, plumose hairs (<1 OD).

Terminalia . As shown in Figs. 45B , 46B , 87A . Gonostylus small, with short setae. Retrorse lobe short, length subequal to gonostylus ( Fig. 87A ).

Taxonomic notes. Lasioglossum boreale belongs to the fulvicorne-fratellum species-group ( Ebmer 1974; Svensson et al. 1977), equivalent to the subgenus Evylaeus (Fratevylaeus) of Pesenko (2007a). It is the only member believed to have a Holarctic distribution ( Svensson et al. 1977). The range of the species is limited to alpine and boreal regions from the type locality in Sweden to mountain ranges in the south-western USA. In the east, it has been recorded from high elevations in New Hampshire as well as high latitudes ( Packer & Taylor 2002; see below). There is genetic variation across geographic localities, particularly high elevation sites in the southwestern USA, but the New Hampshire population doesn’t differ greatly from those in arctic regions of North America ( Packer & Taylor 2002). It is possible that L. boreale is in fact three or more species ( Packer & Taylor 1997, 2002). Additional studies of L. boreale across its range, with comparison to other North American fulvicorne-fratellum group species would be beneficial. The southwestern species L. dasiphorae ( Cockerell 1901b) , known from the Las Vegas Range in New Mexico, is similar to L. boreale , but the type specimen has a longer head (L/W ratio = 1.05) than specimens of L. boreale we measured, although this may be within the range of variation for this species ( Sakagami & Toda 1986).

Biology. This species is a polylectic ground-nester ( Svensson et al. 1977). Nests excavated in Sweden had a single female ( Svensson et al. 1977). The species is only known from high latitudes and altitudes that presumably preclude the formation of annual eusocial colonies.

DNA barcodes. Twenty-eight specimens were sequenced (maximum intraspecific p-distance: 0.9%). The minimum p-distance between L. boreale and L. comagenense is 1.2%. Lasioglossum boreale differs from the other fulvicorne-fratellum species included here by three fixed substitutions: 321(G), 405(C), and 621(G) (see Table 2).

Range. Fig. 55 .

Material examined. 120 (56 females, 64 males). Deposited in BBSL, CNC, CUIC, PCYU, PMAE, and ROMent. For additional records see Svensson et al. 1977 and Packer and Taylor 2002.

CANADA. ALBERTA: Kananaskis, forest reserve; Division 3: Waterton Lake N.P., Cardston Entrance ; BRITISH COLUMBIA: Similkameen Reg.: Hedley; Stikine Reg.: Atlin; Vancouver Is.: Mesachie Lake, Arbutus Hill; Miracle Beach, nr. Oyster River ; MANITOBA: Northern Reg.: Fort Churchill; Churchill, Akuldilk; Churchill, bus stop; Churchill, Krumholz Tundra; Churchill, Ramsay Creek ; Churchill, Twin Lakes Cabins ; NORTHWEST TERRITORIES: Inuvik Reg. : Inuvik ; YUKON TERRITORY: Rampart House ; Snag .

JAPAN. Hokkaido: Sugatami —no—ike, Mts. Taisetsuzan , 1600 m .

USA. ALASKA: Bristol Bay Borough: King Salmon, Naknek R.; Naknek ; NEW HAMPSHIRE: Coos Co.: Mt. Washington, Alpine Garden; Mt. Washington, 4500 ft [1372 m] . WYOMING: Albany Co.: 10,000 ft [3048 m] .

Figures

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 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 53. Lateral habitus of female Lasioglossum (Sphecodogastra) boreale (Svensson, Ebmer & Sakagami). Scale bar = 1 mm.

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

FIGURE 55. Distribution map of Lasioglossum (Sphecodogastra) boreale (Svensson, Ebmer & Sakagami). Heat map indicates predicted suitable range based on maximum entropy niche-modelling. Black circles indicate actual geo-referenced specimen records.

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 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 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 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 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.