Lasioglossum (Dialictus) pallidellum (Ellis)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 234-237

Lasioglossum (Dialictus) pallidellum (Ellis)

( Figure 169A–C )

Halictus pallidellus Ellis, 1914: 151 . ♀. Holotype. ♀ USA, New Mexico, Roswell , 14.iv. [UCMC]. Examined.

Taxonomy. Michener, 1951: Lasioglossum (Chloralictus) pallidellum , p. 1116 (catalogue); Krombein, 1958: Lasioglossum (Chloralictus) pallidellum , p. 230, (catalogue); Hurd, 1979: Dialictus pallidellus , p. 1969 (catalogue); Moure & Hurd, 1987: Dialictus pallidellus , p. 119 (catalogue).

Diagnosis. Females of L. pallidellum can be recognised by the diagnostic combination of a small size (4.0– 4.4 mm), abundant white pubescence, very wide head (length/width ratio = 0.87–0.93), gena narrower than eye, obtuse dorsolateral angle of the pronotum, sparse mesoscutal punctures on central disc (i=1–4d), and metasoma brown. They are similar to L. hyalinum , L. packeri and the Southwestern USA species L. clarissimum (Ellis) . Female L. hyalinum are larger (4.3–5.7 mm), with a narrower head (length/width ratio = 0.94– 0.95) and denser mesoscutal punctures (i=1–2d). Female L. packeri have very wide gena nearly 1.5 times the width of the eye. Female L. clarissimum have pale orange-yellow metasomal terga.

Male unknown.

Redescription. FEMALE. Length 4.03–4.39 mm; head length 1.22–1.27 mm; head width 1.34–1.46 mm; forewing length 3.05–3.11 mm.

Colouration. Head and mesosoma blue with green reflections. Labrum red. Mandible orange. Clypeus with apical half blackish brown. Antenna dark brown, flagellum reddish brown, F2–F10 with ventral surface orange-yellow. Tegula translucent amber. Wing membrane hyaline, venation and pterostigma pale whitish yellow. Legs brown, tibial bases and tarsi orange, metabasitarsus infused with brown. Metasoma dark reddish brown, terga and sterna with apical impressed areas translucent yellow.

Pubescence. White. Dense. Head and mesosoma with dense woolly hairs (1–1.5 OD), longest on genal beard, metanotum and mesopleuron (2–2.5 OD). Lower paraocular area and gena with abundant tomentum. Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasoma with moderately sparse, fine setae. T1 acarinarial fan complete but sparse dorsally. T1 dorsolateral portion with small patch of tomentum. T2 basolaterally and T3–T5 entirely with moderately dense tomentum obscuring most of surface. T2 apicolateral and T3–T4 apical margins with sparse fringes.

Surface sculpture. Face polished, punctation fine. Clypeus polished, apical punctation coarse (i=1–3d), basal punctation fine (i=1–1.5d). Supraclypeal area with punctation moderately dense (i=1–1.5d). Lower paraocular and antennocular areas with punctation dense (i≤d). Upper paraocular area and frons punctation reticulate-punctate (i≤d). Ocellocular area punctate (i=1–1.5d). Gena and postgena polished. Mesoscutum polished, punctation sparse between parapsidal lines (i=1–4d), dense laterad of parapsidal lines (i≤d), contiguous on anterolateral portion. Mesoscutellum similar to mesoscutum, submedial punctation sparse (i=1–5d). Axilla minutely punctate. Metanotum distinctly minutely punctate (i≤d). Preëpisternum obscurely punctate (i≤d). Hypoepimeral area minutely punctate. Mesepisternum polished, punctation distinct (i=1–1.5d). Metepisternum with dorsal half finely striate-reticulate, ventral half polished. Metapostnotum incompletely, finely striate, posterior half polished. Propodeum with dorsolateral slope polished, lateral and posterior surfaces tessellate. Metasomal terga polished except apical impressed areas weakly coriarious, punctation moderately dense throughout (i=1–2.5d).

Structure. Head very wide (length/width ratio = 0.87–0.93). Eyes weakly convergent below (UOD/LOD ratio = 1.09–1.17). Clypeus ½ below suborbital tangent, apicolateral margins convergent. Antennal sockets close (IAD/OAD <0.5). Frontal line carinate, ending 2 OD below median ocellus. Gena narrower than eye. Hypostomal carina parallel. Pronotum with dorsolateral angle obtuse. Pronotal ridge interrupted by oblique sulcus. Inner metatibial spur with 2–3 teeth. Metapostnotum truncate (MMR ratio = 1.22–1.64), posterior margin rounded onto posterior surface. Propodeum with oblique carina absent, lateral carina weak, not reaching dorsal margin.

MALE. Unknown.

Range. Alberta south to Arizona ( Fig. 170 ).

Additional material examined. CANADA: ALBERTA: 1♀ Writing-on-Stone P.P., sand pit, 6.viii.1982 (D.B. McCorquodale); [ PMAE] ; USA: ARIZONA: 3♀ Cochise Co., Willcox , viii.2005 (L. Packer) ; UTAH: 1♀ Kane Co., Little White Rock Cyn. 1 mi N, 12S N4110730 E425809, 17.v.2002 (O. Messinger) ; 1♀ Kane Co., Little White Rock Cyn. 1 mi N, 12S N4110730 E425809, 9.viii.2002 (S. Messinger) ; 1♀ Kane Co., Tibbett Cyn , 12S N4112825 E452127, 13.vi.2002 (C. Davidson); [ PCYU] .

Floral records. CHENOPODIACEAE : Salsola paulsenii , TAMARICACEAE : Tamarix .

Comments. Uncommon. New record for Canada. Morphological comparison suggests a very close relationship to L. clarissimum from the Southwestern USA.

Figures

FIGURE 169. Lasioglossum pallidellum (Ellis). Female (A) lateral habitus; (B) dorsal habitus; (C) face. Scale bars, A– C = 1 mm.

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