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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 mesillense can be recognized by the face short (length/width ratio ~0.8), frons with very fine and dense but distinctly separated punctures, clypeus with distinct apicolateral denticles, mesepisternum with dense punctures (i ≤ 1 pd) becoming crowded and weakly rugulose on the dorsal margin, T2–4 with dark spiracular spots, T1 anterior surface usually shiny, metasomal terga usually with some dense basolateral tomentum, and mesoscutum long (length/width ratio usually ≥0.84). They are most similar to L. minckleyi sp. nov., L. austerum sp. nov., and L. imbriumbrae sp. nov. Females of L. minckleyi sp. nov. have the frons with crowded and indistinct punctures, mesepisternum more densely punctate ventrally (i < 1 pd), T1 anterior surface coriarious, metasomal terga without tomentum, and mesoscutum broad (length/width ratio usually ≤ 0.8). Females of L. austerum sp. nov. have the head and mesosoma with more extensive dull microsculpture, mesepisternum more sparsely and distinctly punctate dorsally (i ≤ 1 pd), T1 anterior surface coriarious, and metasomal terga without tomentum. Females of L. imbriumbrae sp. nov. have the frons with crowded indistinct punctures (nearly rugulose)medially, and mesepisternum and hypoepimeron usually with dense but distinctly separated punctures throughout (i < 1 pd)
Males of L. mesillense can be recognized by the flagellomeres relatively long (F2 about 2 times as long as F1 and 1.6 times as long as broad), face short (length/width ratio ~0.84) and covered in dense tomentum below the ocelli, mesepisternum shiny and moderately densely punctate (i = 1–2 pd), metapostnotum with relatively weak rugae not reaching the posterior margin or extending onto the dorsolateral slope, T2–3 often with basolateral tomentum, and clypeus apical margin and labrum orange to yellow. They are most similar to L. minckleyi sp. nov., L. austerum sp. nov., and L. clematisellum. Males of L. minckleyi sp. nov. have the flagellomeres relatively short (F2 about 1.6 times as long as F1 and 1.25 times as long as broad), frons with crowded and indistinct punctures, and T2–3 never with basolateral tomentum. Males of L. austerum sp. nov. have the flagellomeres relatively short (F2 about 1.75 times as long as F1 and 1.4 times as long as broad) and face with sparse tomentum. Males of L. clematisellum have the clypeus apical margin, labrum, and metasoma black, metapostnotum with strong rugae reaching the posterior margin and extending onto the dorsolateral slope, and T2–3 never with basolateral tomentum.
Redescription
Female
Colouration. Head and mesosoma blue to blue-green; clypeus apical colour black, reddish brown, or orange; labrum black, reddish brown, or orange; mandible orange with black basal spot and red tip; flagellum black to reddish brown dorsally, reddish brown to orange ventrally; pronotal lobe reddish brown to orange; metasoma orange with dark spiracular spots on T3–4 and usually also T2; T4–5 usually darker than T1–3; legs reddish brown with femur-tibia joints, tarsi, and sometimes tibiae mostly orange; tegula pale amber; wing membrane hyaline, veins with subcosta brown, otherwise light brown to pale amber.
Pubescence. Body hair colour white. Tomentum dense on paraocular area, lower frons, gena, pronotal collar and lobe, space between pronotal lobe and tegula, scutum anterolateral margin, metepisternum, T2–3 basolaterally, and T4 throughout; sparse on supraclypeal area, scutum posterolateral margin, preëpisternum, and mesepisternum. Scutum hair thin to moderately plumose. Wing hairs dark or light, short and dense. Acarinarial fan complete, sparse. T2 fringes sparse, T3 fringes sparse.
Surface Sculpture. Clypeus punctures fine and moderately sparse in basal half (i = 1–2 pd), larger and irregular apically (i ≤ 2 pd), diversopunctate, sculpture shiny, sometimes weakly tessellate basally; supraclypeal area punctures sparse to moderately dense (i = 1–4 pd), sculpture shiny or tessellate; paraocular area punctures dense (i < 1 pd), becoming crowded and indistinct around antenna socket, sculpture shiny, becoming imbricate and ruguloso-punctate around antenna socket; frons punctures dense (i < 1 pd), sculpture shiny or weakly imbricate; vertex punctures dense laterally (i < 1 pd), sparser between ocelli (i = 1–2 pd), sculpture shiny or weakly imbricate; gena punctures moderately sparse (i = 1–2 pd), sculpture shiny; postgena sculpture shiny to tessellate, sometimes becoming weakly rugulose posteriorly; tegula punctures absent; scutum punctures moderately sparse (i = 1–3 pd), sometimes becoming dense laterad of parapsidal lines and posteriorly (i < 1 pd), sculpture shiny to tessellate; scutellum punctures dense marginally and on median line (i ≤ 1 pd), sparse submedially (i = 1–5 pd), diversopunctate, sculpture shiny, sometimes becoming tessellate marginally and on median line; metanotum sculpture shiny and finely, densely punctate (i < 1 pd), becoming weakly ruguloso-punctate laterally and anteriorly; metapostnotum rugae strong, anastomosing, not reaching margin, sculpture tessellate; preëpisternum sculpture areolate-rugulose; hypoepimeron punctures dense (i ≤ 1 pd), obscure, sculpture weakly ruguloso-punctate; mesepisternum punctures crowded and indistinct dorsally (i = 0 pd), becoming sparser ventrally (i ≤ 1 pd), sculpture imbricate and ruguloso-punctate dorsally, becoming smooth and shiny ventrally; metepisternum sculpture ruguloso-lineate dorsally, finely reticulate ventrally; propodeum lateral face sculpture tessellate; propodeum posterior face sculpture tessellate with sparse, obscure punctures (i = 1–3 pd); T1 anterior face sculpture shiny to coriarious; T1 dorsal surface punctures fine, sparse (i = 1–3 pd), becoming sparser apicomedially (i = 3–6 pd), nearly impunctate in large apicolateral oval patches, sculpture shiny; T2 disc punctures fine, sparse (i = 1–3 pd), disc sculpture shiny, rim punctures fine, sparse (i = 1–4 pd), rim sculpture weakly coriarious.
Structure. Face length/width ratio 0.8 (± 0.03 SD). Clypeus projecting ~50% below suborbital tangent; clypeal area length/width ratio 0.45 (± 0.04 SD); apicolateral denticles rounded acute points; supraclypeal area length/width ratio 0.67 (± 0.04 SD). Forewing with 3 submarginal cells; pronotal angle obtuse, sometimes nearly right-angled; tegula shape normal. Intertegular distance 0.87 (± 0.08 SD) mm. Scutum length/width ratio 0.86 (± 0.03 SD); scutum/scutellum length ratio 2.79 (± 0.15 SD); scutellum/metanotum length ratio 1.69 (± 0.14 SD); metanotum/metapostnotum length ratio 0.61 (± 0.07 SD). Propodeum lateral carinae not reaching dorsal margin; oblique carina absent. T2 depressed apical rim length less than 50% of segment. (n = 12)
Male
Colouration. Head and mesosoma blue-green to olive green; clypeus apical colour orange to yellow; labrum orange to yellow; mandible orange to yellow with brown basal spot and red tip; flagellum reddish brown, sometimes orange ventrally; pronotal lobe orange; metasoma black to reddish brown with rims of terga and sterna and downcurved lateral areas of terga becoming orange to translucent yellow to brown, dark spiracular spots on T2–4; legs orange to yellow with coxae, trochanters, femora, and tibiae sometimes reddish brown; tegula orange; wing membrane hyaline, veins with subcosta dark brown, otherwise orange to dark brown.
Pubescence. Body hair colour white. Tomentum dense on face below ocelli, gena, pronotal collar and lobe, space between pronotal lobe and tegula, and sometimes T2–4 basolaterally; sparse on episterna and sometimes T5 basally. Scutum hair thin to densely plumose. Sterna hair short (0.75–1.25 OD), moderately plumose, dense and erect. Wing hairs dark or light, short and sparse.
Surface Sculpture. Clypeus punctures fine, moderately sparse (i = 1–3 pd), sculpture shiny; supraclypeal area punctures dense to moderately dense (i ≤ 2 pd), sculpture shiny; paraocular area punctures dense (i < 1 pd), sculpture shiny; frons punctures dense (i < 1 pd), sculpture shiny; vertex punctures moderately dense laterally (i = 1–2 pd), sparse medially (i = 1–4 pd), sculpture shiny; gena punctures sparse (i = 1–3 pd), sculpture shiny; postgena sculpture shiny to imbricate, sometimes lineolate; tegula punctures absent; scutum punctures moderately sparse (i = 1–2 pd), becoming sparse submedially (i = 1–3 pd), sculpture shiny, becoming tessellate anteromedially; scutellum punctures dense marginally and on median line (i ≤ 1 pd), sparse submedially (i = 1–4 pd), sculpture shiny; metanotum sculpture shiny and finely, sparsely punctate (i = 1–4 pd); metapostnotum rugae strong or weak, anastomosing or subparallel, reaching or not reaching margin, sculpture shiny to imbricate; preëpisternum sculpture areolate-rugulose; hypoepimeron punctures dense (i < 1 pd), sculpture shiny; mesepisternum punctures moderately dense (i = 1–2 pd), sculpture shiny; metepisternum sculpture lineate dorsally, areolate ventrally; propodeum lateral face punctures obscure, sculpture rugulose; propodeum posterior face sculpture shiny and finely, sparsely punctate (i = 1–4 pd); T1 anterior face sculpture shiny; T1 dorsal surface punctures sparse (i = 1–4 pd), sculpture shiny; T2 disc punctures moderately sparse (i = 1–3 pd), disc sculpture shiny, rim punctures sparse medially (i = 1–4 pd), absent laterally, rim sculpture shiny.
Structure. Face length/width ratio 0.84 (± 0.03 SD). F1:pedicel length ratio 1.02 (± 0.13 SD); F2:F1 length ratio 1.99 (± 0.24 SD); F2 length/width ratio 1.57 (± 0.17 SD); F9 length/width ratio 1.32 (± 0.13 SD). Forewing with 3 submarginal cells; pronotal angle obtuse; tegula shape normal. Intertegular distance 0.88 (± 0.05 SD) mm. Scutum length/width ratio 0.79 (± 0.05 SD); scutum/scutellum length ratio 3.18 (± 0.28 SD); scutellum/metanotum length ratio 1.48 (± 0.21 SD); metanotum/metapostnotum length ratio 0.68 (± 0.07 SD). Propodeum lateral carinae not reaching dorsal margin; oblique carina absent. (n = 10)
Genitalia. As in Fig. 90G. Gonocoxite broad, weakly truncate. Gonostylus broad, weakly concave apically, with a few long hairs. Retrorse lobe relatively small, ovoid, covered in sparse short hairs.
Range
Colorado south to Chihuahua, west to California (Fig. 57).
Floral Records
AMARANTHACEAE Juss. Chenopodium L. C. neomexicanum Standl. • Salsola L. S. iberica Sennen & Pau • ASTERACEAE Giseke: Baccharis: B. sarothroides A.Gray • Berlandiera • Ericameria • Erigeron: E. divergens Torr. & A.Gray • Laennecia: L. coulteri (A.Gray) G.L. Nesom • Pectis • BIGONIACEAE Juss. Chilopsis D. Don: C. linearis (Cav.) Sweet • BORAGINACEAE Juss. Nama L. • Phacelia Juss. • BRASSICACEAE Burnett: Lepidium L. L. fremontii S. Watson • Physaria (Nutt. ex Torr. & A.Gray) A.Gray: P. gordonii (A.Gray) O’Kane & Al-Shehbaz • Stanleya Nutt. S. pinnata (Pursh) Britton • CLEOMACEAE Bercht. & J. Presl: Cleome L. C. serrulata Pursh • Cleomella DC. C. obtusifolia Torr. & Frém. • Wislizenia Engelm. W. refracta Engelm. • EUPHORBIACEAE Juss. Croton L. • FABACEAE Juss. Medicago: M. sativa L. • Melilotus: M. indicus (L.) All. (MH87) • Parkinsonia: P. aculeata L. • Prosopis: P. glandulosa Torr. P. g. var. torreyana (L.D. Benson) M.C. Johnst. • LOASACEAE Juss. Mentzelia L. M. pumila Torr. & A.Gray • MALVACEAE Juss. Malvastrum A.Gray • ONAGRACEAE Juss. Gaura L. G. mollis E. James • SALICACEAE Mirb. Salix L. S. gooddingii C.R. Ball • TAMARICACEAE Link: Tamarix L. T. chinensis Lour. • T. ramosissima Ledeb. • VERBENACEAE J. St.-Hil. Glandularia J. F. Gmel. G. bipinnatifida (Schauer) Nutt. • ZYGOPHYLLACEAE R.Br. Kallstroemia Scop. K. grandiflora Torr. ex A.Gray • Larrea Cav. L. tridentata (Sessé & Moc. ex DC.) Coville.
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