Lasioglossum (Dialictus) pavoninum (Ellis)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 241-244

Lasioglossum (Dialictus) pavoninum (Ellis)

( Figures 173A–C , 174A–F )

Halictus pavoninus Ellis, 1913: 206 . ♀.

Holotype. ♀ USA, Colorado, Tolland, altitude 8900ft, near the Mountain Laboratory , [ NMNH:]. Examined. Halictus (Chloralictus) evestigatus Sandhouse, 1924: 27 . ♂. [new synonymy]

Holotype. ♂ USA, Colorado, Ward , 10.viii., (Cockerell), [ NMNH: 26425]. Examined.

Halictus (Chloralictus) pikei Sandhouse, 1924: 28 . ♂. [new synonymy]

Holotype. ♂ USA, Colorado, Printing Office, Pikes Peak , 17.ix., (Cockerell), [ NMNH: 26426]. Examined.

Halictus (Chloralictus) abietum Michener, 1936: 281 . ♀ ♂. [new synonymy]

Holotype. ♀ USA, Colorado, Long Peak Inn , 9000ft., 26.viii.1934, (Cockerell), [ CAS: 4715]. Examined.

Taxonomy. Michener, 1951: Lasioglossum (Chloralictus) abietum , p. 1111, L. (C.) evestigatum , p. 1113, L. (C.) pavoninum , p. 1115, L. (C.) pikei , p. 1115 (catalogue); Hurd, 1979: Dialictus abietus , p. 1963, D. evestigatus , p. 1966, D. pavoninus , p. 1969, D. pikei , p. 1970 (catalogue); Moure & Hurd, 1987: Dialictus abietus , p. 87, D. evestigatus , p. 100, D. pavoninus , p. 120, D. pikei , p. 123 (catalogue).

Diagnosis. Females of L. pavoninum can be recognised by the diagnostic combination of an elongate head (length/width ratio = 1.03–1.08), dense mesoscutal punctation (i≤d), reticulate-punctate mesepisternum, elongate propodeal dorsal surface which is nearly equal to mesoscutellum, green metasomal terga with reddish brown apical margins, lack of T1 acarinarial appressed fan and T2–T5 with sparse tomentum. They are superficially similar to L. macroprosopum which have the metasomal terga brown and distinct T1 acarinarial fan.

Males of L. pavoninum are similar to females but may be further recognised by the bright yellow apical half of the clypeus, elongate antenna and deep puncture of the metasomal terga that are absent on the apical impressed areas. They are similar to L. succinipenne and L. pilosum which both have yellow on the clypeus limited to the apical margin and distinct punctures on the apical impressed areas of the metasomal terga.

Redescription. FEMALE. Length 5.19–5.80 mm; head length 1.49–1.63 mm; head width 1.39–1.54 mm forewing length 4.09–4.27 mm.

Colouration. Head and mesosoma bluish green. Clypeus with apical 2/3 blackish brown and basal portion, and supraclypeal area bronzed. Antenna dark brown, flagellum with ventral surface light brown to orange. Tegula reddish brown. Wing membrane subhyaline, venation and pterostigma brownish orange. Legs brown, medio- and distitarsi reddish brown. Metasomal terga green, sterna brown, apical impressed margins translucent brownish yellow.

Pubescence. Dull white. Moderately sparse. Head and mesosoma with moderately dense woolly hairs (1– 1.5 OD), longest on genal beard, metanotum and mesopleuron (2–2.5 OD). Paraocular area and gena without tomentum. Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with moderately dense, fine setae. T1 acarinarial fan absent. T2–T4 basolaterally with sparse tomentum. T2 apicolateral and T3–T4 apical margins with sparse fringes.

Surface sculpture. Face imbricate, punctation moderately strong. Clypeus with apical half polished, punctation moderately sparse (i=1–3d). Supraclypeal area with punctation moderately sparse (i=1–2d). Lower paraocular area punctation dense (i≤d). Antennocular area punctation moderately dense (i=1–1.5d). Upper paraocular area, frons and ocellocular area punctate-reticulate. Gena and postgena lineolate, punctation obscure (i=1–4d). Mesoscutum polished, punctation dense (i≤d), moderately dense submedially (i=1–1.5d). Mesoscutellum similar to mesoscutum, submedial punctation moderately dense (i=1–1.5d). Axilla punctate. Metanotum ruguloso-punctate. Preëpisternum rugulose. Hypoepimeral area weakly reticulate-punctate. Mesepisternum reticulate-punctate. Metepisternum with dorsal third striate, ventral portion imbricate. Metapostnotum incompletely rugoso-striate, posterior margin imbricate. Propodeum with dorsolateral slope rugulosoimbricate, lateral and posterior surfaces imbricate. Metasomal terga polished except apical impressed areas weakly coriarious, punctation moderately strong and dense (i=1–2d), obscure on apical margins.

Structure. Head elongate (length/width ratio = 1.03–1.08). Eyes weakly convergent below (UOD/LOD ratio = 1.14–1.15). Clypeus 2/3 below suborbital tangent, apicolateral margins convergent. Antennal sockets close (IAD/OAD <0.5). Frontal line carinate, ending 2.5 OD below median ocellus. Gena narrower than eye. Hypostomal carina parallel. Inner metatibial spur pectinate with 3–5 teeth. Metapostnotum elongate (MMR ratio = 1.08–1.17), posterior margin rounded onto posterior surface. Propodeum with oblique carina relatively strong, lateral carina short, reaching less than halfway to dorsal margin.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 5.00– 5.43 mm; head length 1.57–1.58 mm; head width 1.33–1.37 mm; forewing length 3.66–3.78 mm.

Colouration. Head and mesosoma more bluish. Clypeus with apical half bright yellow. Flagellum with ventral surface bright yellow. Pronotal lobe posterior margin yellow. Legs brown, Tibial bases and apices, and yellow. Metasomal terga very weakly metallic.

Pubescence. Clypeus with sparse tomentum. Lower paraocular area, and supraclypeal area with dense tomentum. Upper paraocular area and lower frons with sparse tomentum. T2–T4 basolaterally with very sparse tomentum. S3–S5 apicolaterally with subappressed hairs (1–1.5 OD).

Surface sculpture. Mesepisternum weakly reticulate-punctate.

Structure. Head very elongate (length/width ratio = 1.16–1.18). Eyes strongly convergent below (UOD/ LOD ratio = 1.41–1.42). Clypeus 2/3 below suborbital tangent, apicolateral margins subparallel. Antennal sockets distant (IAD/OAD> 1.0). Frontal line carinate, ending 1.5 OD below median ocellus. IOD subequal to OOD. Median ocellus clearly above upper eye tangent. Pedicel shorter than F1. F2 length 1.4–1.6X F1. F2– F10 moderately short (length/width ratio = 1.38–1.50). Metapostnotum elongate (MMR ratio = 1.14–1.20), posterior margin rounded onto posterior surface.

Terminalia . S7 with median lobe wide, columnar, apex flat ( Fig. 174F ). S8 with apicomedial margin strongly convex ( Fig. 174F ). Genitalia as in Fig. 174D–E . Gonobase with ventral arms thick, widely separated. Gonostylus very large, covered with elongate setae. Retrorse lobe elongate, narrow, apical setae elongate.

Range. Northwest and Yukon Territories south to Colorado ( Fig. 170 ).

Additional material examined. CANADA: ALBERTA: 1♀ Redwood Mdws., Hwy 22, N50.99931 W114.49374, 1230 m, 19.vi.2007 (Gibbs & Sheffield); [ PCYU] ; MANITOBA: 1♀ Gillam , 24.vii.1949 (J.B. Wallis); [ CNC] ; NORTHWEST TERRITORIES: 2 ♀ Yellowknife, Ingram Trail , N62º37.5, W113º21.4, 30.vi.05, “fireweed, Tibbett burn” (A. Gunn) ; YUKON TERRITORY: 1♂, Takhini Hot Springs , N60.881 W135.369, 22.vii.1992 (J. Taylor) ; USA: COLORADO: 1♀ 2♂, Park Co., Pennsylvania Mt. , 31.viii.1980 (O. Kendall); [ PCYU] .

Floral Records. ONAGRACEAE : Chamerion augustifolium (= Epilobium angustifolium ).

Comments. Uncommon. Individuals from Colorado and the Northwest Territories were both collected on fireweed ( C. augustifolium ) which might be a coincidence or could be indicative of a floral preference. Several distantly related Lasioglossum are known to specialize on Onagraceae (McGinley 2003) . A combination of morphological examination and preliminary molecular phylogenetic study suggest close affinities of this species to the L. smeathmanellum species-group of Eurasia rather than any other North American Dialictus (J. Gibbs in prep.).

Figures

FIGURE 170. Distribution of Lasioglossum pallidellum (dark grey), L. paradmirandum (medium grey), and L. pavoninum (light grey).

FIGURE 173. Lasioglossum pavoninum (Ellis). Female (A) lateral habitus; (B) dorsal habitus; (C) face. Scale bars, A–C = 1 mm.

FIGURE 174. Lasioglossum pavoninum (Ellis). 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.