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Extracted from: Gardner, J. and J. Gibbs. 2020. The ‘red-tailed’ Lasioglossum (Dialictus) (Hymenoptera: Halictidae)
of the western Nearctic. European Journal of Taxonomy 725: 1–242
Diagnosis
Females of Lasioglossum pallidellum can be recognized by most of the body covered in very dense white tomentum, head and mesosoma shiny and sparsely punctate (i = 1–3 pd), metapostnotum shiny with weak rugae not reaching the rounded posterior margin, face short (length/width ratio ~0.78), and T2–4 with dark spiracular spots. They are most similar to L. julipile sp. nov. Females of L. julipile sp. nov. have the metapostnotum with strong rugae reaching the posterior margin and T2 without dark spiracular spots.
Males of L. pallidellum can be recognized by the same characters as for females, although the metapostnotal rugae are sometimes stronger and nearly reaching the posterior margin, and the dark spiracular spots are only visible in red-tailed forms. In addition, they have the flagellomeres relatively short (F2 about 1.75 times as long as F1 and 1.25 times as long as broad), gonocoxite very broad, and gonostylus large and boot-shaped. They are most similar to L. julipile sp. nov. Males of L. julipile sp. nov. have the mesosoma and metasoma with less extensive tomentum (especially noticeable on T2–4 basolaterally), metasoma always completely black, and gonocoxite and gonostylus narrower with no unusual modifications.
Rediscription
Female
See Gibbs (2010) for a complete redescription of the female (but note that the metasoma colour can vary from black to orange).
Male
Colouration. Head and mesosoma blue to blue-green; clypeus apical colour reddish brown; labrum reddish brown to orange; mandible orange with black basal spot and red tip; flagellum reddish brown dorsally, yellow-orange ventrally; pronotal lobe reddish brown; metasoma black or reddish brown with rims of terga and sterna narrowly translucent reddish brown and downcurved lateral areas of terga becoming narrowly transparent; legs reddish brown with femur-tibia joints, base and apex of tibiae, and tarsi yellow; tegula pale amber; wing membrane hyaline, veins with subcosta and costa apically brown, otherwise pale amber.
Pubescence. Body hair colour white. Tomentum dense on head except postgena and between ocelli, mesosoma except pronotum anterior face, scutum and scutellum medially, and propodeum, T1–3 basally and laterally, and T4–6 throughout; sparse on propodeum posterolateral slope. Scutum hair densely plumose. Sterna hair short (1–1.5 OD), densely plumose, dense and erect. Wing hairs light, short and dense.
Surface Sculpture. Clypeus punctures moderately dense (i = 1–2 pd), sculpture shiny; supraclypeal area punctures dense (i ≤ 1 pd), sculpture shiny; paraocular area punctures dense (i ≤ 1 pd), sculpture shiny; frons punctures dense (i < 1 pd), sculpture shiny; vertex punctures dense laterally (i < 1 pd), moderately sparse medially (i = 1–2 pd), sculpture shiny; gena punctures moderately dense (i = 1–2 pd), sculpture shiny; postgena sculpture shiny, becoming tessellate laterad of hypostomal carina; tegula punctures absent; scutum punctures sparse (i = 1–4 pd), becoming dense marginally (i ≤ 1 pd), sculpture shiny; scutellum punctures sparse (i = 1–3 pd), sculpture shiny; metanotum sculpture shiny and finely, sparsely punctate (i = 1–3 pd); metapostnotum rugae strong, subparallel, not reaching margin, sculpture weakly imbricate; preëpisternum sculpture areolate; hypoepimeron punctures crowded (i = 0 pd), sculpture shiny; mesepisternum punctures dense (i < 1 pd), sculpture shiny; metepisternum sculpture lineate dorsally, areolate ventrally; propodeum lateral face punctures dense (i < 1 pd), obscure, sculpture weakly imbricate; propodeum posterior face sculpture shiny and sparsely punctate (i = 1–4 pd); T1 anterior face sculpture shiny; T1 dorsal surface punctures sparse (i = 1–3 pd), sculpture shiny; T2 disc punctures moderately dense (i = 1–2 pd), becoming sparse apicomedially (i = 1–3 pd), disc sculpture shiny, rim punctures minute, very sparse (i = 3–6 pd), rim sculpture shin
Structure. Face length/width ratio 0.82 (± 0.02 SD). F1:pedicel length ratio 1.08 (± 0.21 SD); F2:F1 length ratio 1.75 (± 0.27 SD); F2 length/width ratio 1.26 (± 0.09 SD); F9 length/width ratio 1.11 (± 0.12 SD). Forewing with 3 submarginal cells; pronotal angle obtuse; tegula shape normal. Intertegular distance 0.9 (± 0.03 SD) mm. Scutum length/width ratio 0.77 (± 0.05 SD); scutum/scutellum length ratio 2.54 (± 0.16 SD); scutellum/metanotum length ratio 1.52 (± 0.11 SD); metanotum/metapostnotum length ratio 0.76 (± 0.08 SD). Propodeum lateral carinae not reaching dorsal margin; oblique carina absent. (n = 5)
Genitalia. As in Fig. 90K. Gonocoxite very broad, cashew-shaped. Gonostylus very large, boot-shaped, with a few long hairs. Retrorse lobe broad, ovoid, with dense short hairs concentrated at apex.
Range
Alberta south to Nuevo Leon and west to California (Fig. 69).
Floral Records
AMARANTHACEAE Juss. Salsola L. S. paulsenii Litv. • ASTERACEAE Giseke: Aplopappus • Ericameria: E. nauseosa (Pall. ex Pursh) G.L. Nesom & Baird: E. n. var. nauseosa (Pall. ex Pursh) G.L. Nesom & Baird • Gutierrezia: G. microcephala (DC.) A.Gray • Isocoma: I. acradenia (Greene) Greene • CLEOMACEAE Bercht. & J. Presl: Cleomella DC. C. obtusifolia Torr. & Frém. • OxystylisTorr. & Frém. O. lutea Torr. & Frém. • Wislizenia Engelm. W. refracta Engelm. • FABACEAE Juss. Acacia: A. greggii A.Gray • Astragalus: A. lentiginosus Hook. • Melilotus • Prosopis: P. glandulosaTorr. • POLYGONACEAE Juss. Eriogonum Michx. E. trichopes Torr. • ROSACEAE Juss. Prunus L. • SALICACEAE Mirb. Salix L. S. exigua Nutt. • TAMARICACEAE Link: Tamarix L. T. aralensis Bunge.
Retrieved from: Gibbs, J. 2010. Revision of the metallic species of Lasioglossum (Dialictus)in Canada (Hymenoptera, Halictidae, Halictini). Zootaxa; 2591, 234-237
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). Pre�pisternum 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 � 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.
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