Lasioglossum (Dialictus) simplex (Robertson)

Gibbs, Jason, 2011, Revision of the metallic Lasioglossum (Dialictus) of eastern North America (Hymenoptera: Halictidae: Halictini), Zootaxa 3073, pp. 1-216 : 177-180

Lasioglossum (Dialictus) simplex (Robertson)

( Figures 192–196 )

Paralictus simplex Robertson, 1901: 230 . Ƥ.

Lectotype. Ƥ USA, Illinois, Macoupin Co., Carlinville, 17.iv.1893 (C. Robertson); [INHS: 13817] by W. E. LaBerge (in Webb 1980). Examined.

Halictus (Chloralictus) malinus Sandhouse, 1924: 40 . 3. [new synonymy] Holotype. 3 USA, Virginia, East Falls Church, 16.vii., on Daucus carota (S.A. Rohwer) ; [NMNH: 26445]. Examined. [gynandromorph]

Taxonomy. Michener, 1951: Lasioglossum (Chloralictus) malinum , p. 1115, L. (P.) simplex , p. 1119 (catalogue); Mitchell, 1960: Paralictus simplex , p. 449 (redescription); Hurd, 1979: Dialictus malinus , p. 1968 (catalogue); Moure and Hurd, 1987: Dialictus malinus , p. 111, Paralictus simplex , p. 143 (catalogue).

Diagnosis. Female L. simplex can be recognised as a parasitic Dialictus by head wide (length/width ratio = 0.84– 0.86) ( Fig. 192 B); mandible without preapical tooth; labrum with apical process flat, dorsal keel absent ( Fig. 6 B); and scopal hairs weak. They may be further distinguished by mandible relatively short, not extending beyond opposing clypeal angle; gena subequal in width to eye; and pronotal ridge rounded. Female L. simplex is most similar to L. furunculum , L. izawsum , and L. sitocleptum Gibbs , all of which have the pronotal ridge carinate. Female L. izawsum have a distinct preapical tooth.

Male L. simplex can be recognised by the combination of face with dense subappressed tomentum ( Fig. 194 B); flagellomeres short (length/width ratio = 1.40–1.58); mesoscutum polished, punctures fine and sparse between parapsidal lines (i=1–2d) ( Fig. 195 ); metapostnotum with anastomosing rugae, posterior margin narrowly rounded; and metasomal terga with apical impressed areas nearly impunctate with a few scattered punctures.

Description. FEMALE. Length 5.32–5.63 mm; head length 1.49–1.51 mm; head width 1.73–1.80 mm; forewing length 3.51–3.93 mm.

Colouration. Head and mesosoma bluish green. Clypeus with apical 1/2 blackish brown. Antenna dark brown, F8– F10 with ventral surface orange-yellow. Tegula amber. Wing venation and stigma dark yellowish brown. Legs brown, except tarsi reddish brown. Metasoma dark brown, terga and sterna with apical margins translucent brownish yellow.

Pubescence. Dull white. Sparse. Head and mesosoma with moderately dense woolly hairs (1–1.5 OD), longest on genal beard, metanotum, and mesopleuron (2–2.5 OD). Face without appressed hairs. Pronotal collar without dense tomentum. Propodeum with moderately sparse plumose hairs on lateral and posterior surfaces (1.5–2 OD). Mesofemoral and mesotibial combs dense but short relative to non-parasitic species. Metafemoral scopa reduced relative to nest-building species, only a few elongate hairs curving above ventral surface. Penicillus greatly reduced, indistinguishable from other hairs. Metasoma moderately sparse, fine hairs. T1 acarinarial fan sparse, incomplete with dorsal opening greater than width of lateral appressed hair patches. T2–T3 basolaterally and T4 entirely with very sparse tomentum. T2 apicolateral and T3–T4 apical margins with very sparse fringes. Sternal hairs erect, posteriorly directed (1.5–2 OD).

Surface sculpture. Face polished, weakly imbricate, punctation fine. Clypeus polished, punctation sparse (i=1–4d). Supraclypeal area with punctation moderately sparse (i=1–3d). Lower paraocular and antennocular areas with punctation moderately sparse (i=1–2d). Upper paraocular area and frons reticulate-punctate. Ocellocular area polished, punctate (i=1–2d). Gena faintly lineolate. Postgena imbricate. Mesoscutum weakly imbricate, more polished posteriorly, punctation fine, sparse between parapsidal lines (i=1–2.5d), moderately sparse laterad of parapsidal line (i=0.5–1.5d) and dense on anterolateral portion (i≤d). Mesoscutellum similar to mesoscutum, submedial punctation sparse (i=1–3d). Axilla punctate. Metanotum imbricate. Preëpisternum rugulose. Hypoepimeral area ruguloso-imbricate. Mesepisternum upper half rugulose, lower half imbricate. Metepisternum with upper 1/3 carinulate, lower 2/3 imbricate. Metapostnotum completely rugoso-carinulate, posterior margin imbricate. Propodeum with dorsolateral slope carinulate, lateral surface imbricate, posterior surface imbricate-tessellate. Metasomal terga polished except apical impressed areas faintly coriarious, punctation on basal halves moderately sparse (i=1–2.5d), apical half sparse (i=2.5–4d).

Structure. Head very wide (length/width ratio = 0.84–0.86). Eyes convergent below (UOD/LOD ratio = 1.25–1.26). Labrum enlarged and flattened with distinct basal tubercle, apical process without dorsal keel. Mandibles slender without preapical tooth. Clypeus 1/3 below suborbital tangent, apicolateral margins strongly convergent. Antennal sockets distant (IAD/OAD> 0.8). Frontal line carinate, ending 2 OD below median ocellus. IOD subequal to OOD. Gena subequal to eye. Pronotal dorsolateral angle obtuse. Pronotal ridge broadly rounded, interrupted by oblique sulcus. Basitibial plate with lower carina weak. Inner metatibial spur pectinate with 3–4 branches. Metapostnotum truncate (MMR ratio = 1.25), posterior margin narrowly rounded onto posterior surface. Propodeum with oblique carina very weak, lateral carina short, not reaching dorsal margin. T5 medial specialized area reduced in size relative to non-parasitic species.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 4.30–4.72 mm; head length 1.37–1.56 mm; head width 1.46–1.58 mm; forewing length 3.03–3.75 mm.

Colouration. Mandible brownish yellow. Flagellum with ventral surface reddish. Legs brown, except tibial bases and apices, and tarsi brownish yellow.

Pubescence. Face below median ocellus with dense tomentum obscuring surface, densest on lower paraocular area. S2–S3 with dense apical subappressed hairs and S4 with apicolateral subappressed hairs.

Surface sculpture. Mesoscutum polished. Metasomal terga with apical impressed margins nearly impunctate.

Structure. Head wide (length/width ratio = 0.93–0.98). Eyes strongly convergent below (UOD/LOD ratio = 1.43– 1.52). Clypeus 2/3 below suborbital line, apicolateral margins subparallel. Antennal sockets distant (IAD/OAD> 1.3). Frontal line carinate, ending <2 OD below median ocellus. Hypostomal carinae only slightly divergent towards mandibles. Pedicel shorter than F1. F2 length 1.4–1.7X F1. F2–F10 moderately elongate (length/width ratio = 1.40–1.58). Metapostnotum moderately elongate (MMR ratio = 1.18), posterior margin sharply angled onto posterior surface.

Terminalia . S7 with median lobe broadly acuminate, apex rounded ( Fig. 196 ). S8 with apicomedial margin weakly convex ( Fig. 196 ). Genital capsule as in Fig. 196 . Gonobase with ventral arms narrowly separated. Volsella roughly ovoid. Gonostylus narrow and elongate, dorsal setae elongate. Retrorse lobe elongate, attenuated apically.

Range. Maryland west to Kansas ( Fig. 185 ). USA: IA, IL, KS, MD, VA.

Additional material examined. USA: ILLINOIS: 13 ( Chloralictus versatus lectoallotype), Carlinville (C. Robertson); 2ƤƤ paratypes Carlinville (C. Robertson); [ INHS]; IOWA: 1Ƥ Woodbury Co., Sioux City, 15.vii.1921 (C.N. Ainslie); [ AMNH]; KANSAS: 2ƤƤ Lawrence vicinity, 2.x.1976 (S. Laroca); [ SEMC]; MARYLAND: 1Ƥ Pr. George’s Co., N39.02788 W076.8856, 13–14.iv.2005 (S.W. Droege); 13 Worcester Co., N38.1616 W075.1704, 20.ix.2006 (S.W. Droege); [ PCYU]; VIRGINIA: 13 ( H. (C.) malinus paratype) E[ast] Falls Ch [urch], 16.vii (S.A. Rohwer); [ CUIC].

Floral records. APIACEAE : Cicuta maculata , Daucus carota , Zizia aurea ; ASTERACEAE : Achillea millefolium , Solidago ; RANUNCULACEAE : Ranunculus fascicularis ; ROSACEAE : Rubus flagellaris .

DNA Barcode. Available. Multiple sequences.

Comments. Rare.

Lasioglossum simplex is evidently a social parasite of L. trigeminum and/or L. versatum . There is some confusion as to which of these species was studied by Michener (1966).

The holotype of H. (C.) malinus is a gynandromorph. The head is clearly male and the metasoma is clearly female. The sex of the mesosoma is evidently mixed. The inner metatibial spur is serrate like a male on the right side but is pectinate like a female on the left side.

Figures

FIGURE 6. Labrum of female Dialictus; (A) nest-building species, (B) parasitic species. Arrows indicate apical process. (From Gibbs 2010 b).

FIGURE 185. Distribution map of Lasioglossum rozeni (circles) and L. simplex (stars).

FIGURE 192. Lasioglossum simplex (Robertson) female, (A) lateral habitus, (B) face. Scale bars = 1 mm.

FIGURE 193. Lasioglossum simplex (Robertson) female, dorsal view of mesosoma.

FIGURE 194. Lasioglossum simplex (Robertson) male, (A) lateral habitus, (B) face. Scale bars = 1 mm.

FIGURE 195. Lasioglossum simplex (Robertson) female, dorsal view of mesosoma.

FIGURE 196. Lasioglossum simplex (Robertson) male terminalia, (A) ventral view, (B) dorsal view. Scale bar = 0.5 mm.