Lasioglossum (Dialictus) austerum, Gardner & Gibbs, 2020

Gardner, Joel & Gibbs, Jason, 2020, The ‘ red-tailed’ Lasioglossum (Dialictus) (Hymenoptera: Halictidae) of the western Nearctic, European Journal of Taxonomy 725, pp. 1-242 : 27-31

Lasioglossum (Dialictus) austerum sp. nov.

urn:lsid:zoobank.org:act:ADA77DE6-7290-46F5-A476-A932354952D5

Figs 13–15

Diagnosis

Females of Lasioglossum austerum sp. nov. can be recognized by the metasomal terga lacking tomentum, head and mesosoma mostly covered with dull microsculpture, T1 anterior surface coriarious, frons punctures fine and distinctly separated, mesepisternum moderately densely punctate (i ≤ 1 pd), and T2–4 with dark spiracular spots. They are most similar to L. mesillense and L. minckleyi sp. nov. Both of these species have the face and mesosoma mostly shiny and mesepisternum more densely punctate (i <1 pd at least in dorsal half). In addition, females of L. mesillense often have the metasomal terga with basolateral tomentum, and females of L. minckleyi sp. nov. have the frons with slightly larger, crowded, indistinct punctures (i=0d).

Males of L. austerum sp. nov. can be recognized by the face short (length/width ratio ~0.8), mesepisternum shiny with punctures about 1 puncture diameter apart, flagellomeres relatively short (F2 about 1.75 times as long as F1 and 1.4 times as long as broad), and tomentum sparse on the face and largely absent elsewhere. They are most similar to L. mesillense , L. minckleyi sp. nov., and L. decorum sp. nov. Males of L. mesillense have the flagellomeres longer (F2 about 2 times as long as F1 and 1.6 times as long as broad), face below ocelli covered in dense tomentum, and metasomal terga often with basolateral patches of tomentum. Males of L. minckleyi sp. nov. have the mesepisternum more densely punctate (i <1 pd) and face below ocelli covered in dense tomentum. Males of L. decorum sp. nov. have the rims of T1–3 impunctate and face slightly longer (length/width ratio ~0.86) with the clypeus more distinctly projecting below the eyes.

Etymology

The specific epithet austerum is a Latin adjective meaning ‘austere’, ‘plain’, or ‘harsh’. It refers to this species’ habitat in the sparsely populated, hot deserts of the Baja California peninsula, as well as its lack of tomentum. An appropriate translation would be the austere sweat bee.

Material examined

Holotype

MEXICO – Baja California • ♀; 10 mi. S of Punta Prieta; [28.78° N, 114.16° W]; 21 Jun. 1938; Michelbacher and Ross leg.; CAS.

[Verbatim label: 10 mi. S. Punta Prieta, / L. Cal. VI-21-38 // Michelbacher & Ross Collectors // HOLOTYPE / Lasioglossum (Dialictus) austerum Gardner and Gibbs ]

Paratypes

MEXICO – Baja California • 7 ♀♀, 1 ♂; same collection data as for holotype; CAS • 1 ♀; 20 mi. W of San Augustine; [24.1° N, 110.6° W]; 24 Sep. 1941; Ross and Bohart leg.; ex Eriogonum ; CAS . – Baja California Sur • 1 ♀; 15 mi. N of San Ignacio; [27.49° N, 112.9° W]; 29 Sep. 1941; Ross and Bohart leg.; CAS • 1 ♀; 20 mi. N of Mesquital; [26.52° N, 112.35° W]; 27 Sep. 1941; Ross and Bohart leg.; CAS • 1 ♀; 20 mi. W of San Augustine; [24.1° N, 110.6° W]; 24 Sep. 1941; Ross and Bohart leg.; CAS • 1 ♀; 8 km W of Sta. Rita; [24.58° N, 111.54° W]; 11 Jun. 1975; H. Evans, W. Rubink and D. Gwynne leg.; CSUC • 2 ♀♀; Concepcion Bay ; [26.55° N, 111.7° W]; 25 Oct. 1941; Ross and Bohart leg.; CAS • 1 ♀; San Sebastian Bahia , San Nicholas ; [26.6097° N, 111.57° W]; 19 May 1975; P. DeBach leg.; UCRC • 2 ♀♀; Venancio ; [25.86° N, 111.89° W]; 17 Jul. 1938; Michelbacher and Ross leg.; CAS .

Description

Female

COLOURATION. Head and mesosoma blue-green to golden-green; clypeus apical colour black, reddish brown, or orange; labrum reddish brown to orange; mandible orange with black basal spot or band and red tip; flagellum reddish brown dorsally, brown to orange ventrally; pronotal lobe reddish brown to orange; metasoma orange with dark spiracular spots on T2–4; legs reddish brown with femur-tibia joints, base and apex of tibiae, and tarsi orange; tegula orange; wing membrane hyaline or lightly infuscated, veins with subcosta dark brown, otherwise brown to dark brown.

PUBESCENCE. Body hair colour white. Tomentum dense on gena, pronotal collar and lobe, and space between pronotal lobe and tegula; sparse on paraocular area and episterna. Scutum hair thin. Wing hairs dark or light, short and dense. Acarinarial fan complete, sparse. T2 fringes sparse, T3 fringes sparse.

SURFACE SCULPTURE. Clypeus punctures large and irregularly sparse (i <3 pd), becoming fine and moderately dense in basal third (i= 1–2 pd), sculpture shiny, becoming imbricate basally; supraclypeal area punctures sparse (i=1–4 pd), sometimes absent ventromedially, sculpture tessellate, sometimes shiny medially; paraocular area punctures dense (i <1 pd), irregularly sparser around antenna socket (i <2 pd), sculpture tessellate around antenna socket, otherwise shiny; frons punctures dense (i <1 pd), sculpture tessellate or imbricate; vertex punctures dense laterally (i <1 pd), sparse and sometimes obscure medially (i= 1–3 pd), sculpture imbricate, sometimes shiny medially; gena punctures sparse (i =1–3 pd), sculpture shiny, becoming tessellate and weakly lineate posteriorly; postgena sculpture tessellate and weakly lineate, becoming shiny anteriorly; tegula punctures absent; scutum punctures dense to moderately sparse (i=1–3 pd), becoming slightly sparser submedially and anteromedially (i =1–4 pd), sculpture tessellate; scutellum punctures dense marginally and on median line (i <1 pd), sparse submedially (i=1–4 pd), diversopunctate, sculpture tessellate, becoming shiny submedially; metanotum sculpture shiny or tessellate with fine, dense punctures (i <1 pd), becoming sparse and obscure laterally; metapostnotum rugae strong or weak, anastomosing, usually not reaching margin, sculpture finely rugulose to reticulate; preëpisternum sculpture tessellate and weakly areolate-rugulose; hypoepimeron punctures dense (i <1 pd), obscure, sculpture weakly imbricate; mesepisternum punctures dense (i ≤ 1 pd), sculpture weakly imbricate; metepisternum sculpture lineate dorsally, weakly areolaterugulose medially, imbricate ventrally; propodeum lateral face sculpture tessellate; propodeum posterior face sculpture tessellate; T1 anterior face sculpture coriarious; T1 dorsal surface punctures fine, sparse (i =1–4 pd), absent or very sparse in large apicolateral oval patches, sculpture shiny to coriarious; T2 disc punctures fine, sparse (i=1–4 pd), disc sculpture shiny to coriarious, rim punctures fine, sparse (i =1–4 pd), obscure, rim sculpture coriarious.

STRUCTURE. Face length/width ratio 0.83 (± 0.02 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 0.65 (± 0.04 SD). Forewing with 3 submarginal cells; pronotal angle obtuse; tegula shape normal. Intertegular distance 0.9 (± 0.04 SD) mm. Scutum length/width ratio 0.77 (± 0.03 SD); scutum/scutellum length ratio 2.91 (± 0.18 SD); scutellum/metanotum length ratio 1.54 (± 0.13 SD); metanotum/metapostnotum length ratio 0.66 (± 0.06 SD). Propodeum lateral carinae not reaching dorsal margin; oblique carina absent. T2 depressed apical rim length less than 50% of segment. (n= 10)

Male

COLOURATION. Head and mesosoma olive green; clypeus apical colour reddish brown; labrum reddish brown; mandible orange with black basal band and red tip; flagellum reddish brown dorsally, light brown ventrally; pronotal lobe reddish brown to orange; metasoma black to reddish brown with rims of terga and sterna and downcurved lateral areas of terga broadly translucent orange; legs reddish brown with femur-tibia joints, base and apex of tibiae, and tarsi orange; tegula orange; wing membrane hyaline, veins dark brown.

PUBESCENCE. Body hair colour white. Tomentum dense on paraocular area; sparse on face below eye emargination, gena, pronotal angle and lobe, and space between pronotal lobe and tegula. Scutum hair thin. Sterna hair short (1–1.5 OD), moderately plumose, sparse and erect. Wing hairs dark, short and sparse.

SURFACE SCULPTURE. Clypeus punctures dense (i ≤ 1 pd), sculpture shiny; supraclypeal area punctures sparse (i=1–3 pd), sculpture shiny; paraocular area punctures dense (i ≤ 1 pd), sculpture weakly imbricate around antenna socket, otherwise shiny; frons punctures crowded (i=0 pd), sculpture imbricate and finely areolate; vertex punctures dense and obscure laterally (i <1 pd), sparse and distinct medially (i=1–3 pd), sculpture imbricate laterally, shiny medially; gena punctures sparse (i=1–3 pd), sculpture shiny; postgena sculpture shiny and weakly lineate; tegula punctures absent; scutum punctures sparse (i =1–3 pd), sculpture shiny, becoming weakly tessellate anteromedially; scutellum punctures moderately sparse (i=1–2 pd), becoming dense marginally (i ≤ 1 pd), sculpture shiny; metanotum sculpture shiny and finely, sparsely punctate (i=1–4 pd); metapostnotum rugae strong, subparallel, not reaching margin, sculpture weakly tessellate; preëpisternum sculpture areolate-rugulose; hypoepimeron punctures dense (i <1 pd), sculpture shiny; mesepisternum punctures dense (i ≤ 1 pd), sculpture shiny; metepisternum sculpture rugoso-lineate dorsally, smooth and shiny ventrally; propodeum lateral face punctures obscure, sculpture rugulose; propodeum posterior face sculpture shiny; T1 anterior face sculpture weakly coriarious; T1 dorsal surface punctures sparse (i=1–3 pd), sculpture shiny; T2 disc punctures 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 0.8. F1:pedicel length ratio 0.86; F2:F1 length ratio 1.75; F2 length/ width ratio 1.4; F9 length/width ratio 1.26. Forewing with 3 submarginal cells; pronotal angle obtuse; tegula shape normal. Intertegular distance 0.73 mm. Scutum length/width ratio 0.92; scutum/scutellum length ratio 2.65; scutellum/metanotum length ratio 1.55; metanotum/metapostnotum length ratio 0.71. Propodeum lateral carinae not reaching dorsal margin; oblique carina absent. (n= 1)

GENITALIA. Not examined.

Range

Deserts of the Baja California peninsula from Punta Prieta to La Paz ( Fig. 15 ).

Floral records

POLYGONACEAE Juss. Eriogonum Michx.

DNA barcodes

Not available.

Figures

Fig. 13. Lasioglossum (D.) austerum sp. nov., ♀. A. Dorsal habitus. B. Face. C. Lateral habitus. D. Metasoma. E. Propodeum. Scale bars: 1 mm.

Fig. 14. Lasioglossum (D.) austerum sp. nov., ♂. A. Dorsal habitus. B. Face. C. Lateral habitus. D. Propodeum and metasoma. Scale bars: 1 mm.

Fig. 15. Georeferenced collection records of Lasioglossum (D.) austerum sp. nov. (black squares) and predicted distribution by maximum entropy ecological niche modeling in Maxent (colour shading). Warmer colours indicate higher cloglog probability of occurrence.