Lasioglossum (Dialictus) macroprosopum Gibbs, 2010

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 184-188

Lasioglossum (Dialictus) macroprosopum Gibbs , new species

( Figures 140A–C , 141A–F )

Holotype. ♀ CANADA, British Columbia, Okanagan-Similkameen Reg. Dist.. Osoyoos, Osoyoos Oxbows , Rd. 57, N49.0892 W119.5344, 282 m, 25.vii.2008 (L. R. Best); [ PCYU].

Diagnosis. Females of L. macroprosopum are recognisable by the diagnostic combination of large size (6.0– 6.3 mm), elongate head (length/width ratio = 1.05–1.07), dense mesoscutal and mesepisternal punctures, complete T1 acarinarial fan and a lack of dense tomentum on the brown metasomal terga. They are most similar to L. brunneiventre which are smaller (3.7–4.0 mm) with a slightly longer head (length/width ratio = 1.07–1.10). A similar undescribed species of intermediate size (approx. 4.2–5.2 mm) with a very elongate head (length/ width ratio = 1.10–1.17) occurs in the Western USA as far north as southeastern Washington but has abundant tomentum on the metasomal terga.

Males of L. macroprosopum are recognisable by the diagnostic combination of elongate head (length/ width ratio = 1.09), clypeus brown, mesepisternum densely punctate (i≤d), metabasitarsus brownish yellow, and metasomal terga brown with apical impressed areas punctate. They are most similar to L. brunneiventre which are smaller (head width = 1.13–1.22 mm) and pale brown metabasitarsus.

Description. FEMALE. Length 5.98–6.34 mm; head length 1.66–1.73 mm; head width 1.56–1.62 mm; forewing length 4.39–4.76 mm.

Colouration. Head and mesosoma bluish green. Clypeus with apical 2/3 blackish brown, basal 1/3, and supraclypeal area bronze. Antenna dark brown, flagellum with ventral surface pale brownish yellow. Tegula brownish yellow. Wing membrane subhyaline, venation and pterostigma pale brownish yellow. Legs brown. Metasoma reddish brown, terga and sterna with apical margins pale translucent brownish yellow.

Pubescence. White. Moderately dense. Head and mesosoma with moderately dense woolly hairs (1–1.5 OD), longest on genal beard, metanotum and mesopleuron (2–2.5 OD). Lower paraocular area and gena with sparse tomentum not obscuring surface. Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with very dense, fine setae. T1 acarinarial fan complete, mingling with erect hairs on lateral margins. T2 basolateral and T3 basal portions, and T4 with tomentum partially obscuring surface. T2 apicolateral and T3–T4 apical margins with weak fringes.

Surface sculpture. Face weakly imbricate, punctation fine and deep. Clypeus polished, basal margin imbricate, punctation moderately sparse (i=1–3d). Supraclypeal area with punctation moderately sparse (i=1– 2.5d). Lower paraocular and antennocular areas with punctation dense (i≤d). Upper paraocular area, frons and ocellocular area punctate-reticulate. Gena and postgena lineolate. Mesoscutum polished, weakly imbricate anteriorly, punctation fine and deep, dense between parapsidal lines (i≤d) and reticulate laterad of parapsidal lines and on anterolateral portion. Mesoscutellum similar to mesoscutum, submedial punctation moderately sparse (i=1–2d). Axilla punctate. Metanotum imbricate. Preëpisternum reticulate-rugulose. Hypoepimeral area rugulose. Mesepisternum rugulose-punctate (i<d). Metepisternum with dorsal 1/4 striate, ventral portion weakly reticulate. Metapostnotum completely anastomosingly rugose, posterior margin polished. Propodeum with dorsolateral slope and lateral surface imbricate, posterior surface tessellate-imbricate. Metasomal terga polished except apical impressed areas and T1 declivitous surface weakly coriarious, punctation dense throughout (i≤d).

Structure. Head elongate (length/width ratio = 1.05–1.07). Eyes weakly convergent below (UOD/ LOD ratio = 1.15–1.18). Clypeus 2/3 below suborbital line, apicolateral margins convergent. Antennal sockets close (IAD/OAD <0.5). Frontal line carinate, ending 2 OD below median ocellus. Gena narrower than eye. Inner metatibial spur with 3–4 teeth. Metapostnotum moderately elongate (MMR ratio = 1.07–1.28), posterior margin weakly angled onto posterior surface. Propodeum with oblique carina very weak, lateral carina weak, not reaching dorsal surface.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 5.02 mm; head length 1.61 mm; head width 1.48 mm; forewing length 4.36 mm.

Colouration. Flagellomeres with ventral surface orange-yellow. Tibial bases and apices, and tarsi pale brownish yellow.

Pubescence. Face below eye emargination with tomentum partially obscuring surface, except relatively dense on lower paraocular area. Gena with sparse tomentum. Metasomal terga without tomentum. T1 with sparse acarinarial hair fan. S2 and S3–S4 apicolaterally with plumose hairs.

Surface sculpture. Postgena and gena polished. Mesoscutum more polished, punctures between parapsidal lines less dense (i=1–1.5d). Mesepisternal punctation distinct (i=1d).

Structure. Head elongate (length/width ratio = 1.09). Eyes convergent below (UOD/LOD ratio = 1.36). Antennal sockets distant (IAD/OAD> 1.0). Frontal line carinate, ending <2 OD below median ocellus. Pedicel shorter than F1. F2 length 1.9X F1. F2–F10 elongate (length/width ratio = 1.58–1.67). Metapostnotum elongate (MMR ratio = 1.11), posterior margin rounded onto posterior surface.

Terminalia . S7 with median lobe clavate, apex rounded ( Fig. 141F ). S8 with apicomedial margin convex ( Fig. 141F ); genitalia as in Fig. 141D–E . Gonobase with ventral arms narrowly separated. Gonostylus small, dorsal setae elongate. Retrorse lobes elongate, attenuated apically.

Range. British Columbia south to Oregon ( Fig. 139 ).

Allotype. CANADA: BRITISH COLUMBIA: ♂ Okanagan-Similkameen Reg. Dist.. Osoyoos, Mt. Kruger , Strawberry Crk., N49.0300 W119.4929, 415 m, 28.vii.2008 (L. R. Best); [ PCYU].

Paratypes. CANADA: BRITISH COLUMBIA: 5♀ topotypical ; 1♀ Okanagan-Similkameen Reg. Dist .. Oliver, Ripley Lk. , N49.2435 W119.6324, 925 m, 13.vii.2008 (L. R. Best) ; 13♀♀ Okanagan-Similkameen Reg. Dist .. Osoyoos, Mt. Kruger , Strawberry Crk. , N49.0304 W119.4928, 415 m, 24.vii.2008 (L. R. Best) ; 5♀♀ Okanagan-Similkameen Reg. Dist .. Osoyoos, Mt. Kruger , Strawberry Crk. , N49.03 W119.4929, 415 m, 28.vii.2008 (L. R. Best) ; 8♀♀ Okanagan-Similkameen Reg. Dist .. Osoyoos, Mt. Kruger , Strawberry Crk. , N49.0296 W119.4925, 440 m, 29.vii.2008 (L. R. Best) ; 2♀♀ Okanagan-Similkameen Reg. Dist .. Osoyoos, Osoyoos Oxbows. , N49.0902 W119.5373, 282 m, 27.vii.2008 (L. R. Best); [ PCYU] ; 2♀♀ Penticton, West Bench , 26.v.1987 ( R. A. Cannings) ; 1♀ Penticton, West Bench , 27.v.1987 ( R. A. Cannings) ; 1♀ Penticton, West Bench , edge of grassland, 21.iv.1988 ( R. A. Cannings) ; 1♀ Summerland, Southbench , 28.vi.1990 ( R. A. Cannings & H. Nadel); [ RBCM] ; USA: OREGON: 1♀ Baker Co., Farewell Bend S.P., N44.30962 W117.22057, 659 m, 27.vi.2007 (Gibbs & Sheffield); [ PCYU] .

Etymology. The specific epithet is a combination of the Greek “macros” and “prosopo” meaning “long face”.

Comments. Common.

Figures

FIGURE 139. Distribution of Lasioglossum lineatulum (light grey), and L. macroprosopum (dark grey).

FIGURE 140. Lasioglossum macroprosopum new species. Female (A) lateral habitus; (B) dorsal habitus; (C) face. Scale bars, A–C = 1 mm.

FIGURE 141. Lasioglossum macroprosopum new species. Male (A) lateral habitus; (B) dorsal habitus; (C) face; (D) ventral view of genital capsule; (E) dorsal view of genital capsule; (F) S7, S8. Scale bars, A–C = 1 mm, F = 0.5 mm.