Lasioglossum (Dialictus) rozeni Gibbs

Gibbs, Jason, 2011, Revision of the metallic Lasioglossum (Dialictus) of eastern North America (Hymenoptera: Halictidae: Halictini), Zootaxa 3073, pp. 1-216 : 167-171

Lasioglossum (Dialictus) rozeni Gibbs , new species

( Figures 180–184 )

Holotype. Ƥ USA, Maryland, Talbot Co., N38.8 W.076.2833, 7–8.v.2005 (W. Steiner); [ PCYU] Taxonomy. Gibbs, 2010b: Lasioglossum (Dialictus) cephalotes (description, misdet.).

Diagnosis. Female L. rozeni can be recognised by the following diagnostic combination: head wider than mesosoma ( Fig. 181 ); gena wider than eye; labrum with weak basal tubercle, apical process flat, dorsal keel absent; mandible narrow without preapical tooth; pronotal ridge sharply angled and dorsolateral angle acute to orthogonal ( Fig. 181 ); scopa absent; and metapostnotum rugoso-carinulate. ( Fig. 181 ) They are most similar to L. platyparium and L. cephalotes . Female L. platyparium have a strong basal tubercle on the labrum and a wide mandible that only converges to a point near the apex. Female L. cephalotes also have a wide mandible and metapostnotum smooth with rugae if present limited to base.

Male L. rozeni can be recognised by the following diagnostic combination: head wide, lower paraocular area with very dense tomentum ( Fig. 182 B), and pronotal collar strong. They are similar to L. platyparium , which has less dense facial tomentum and pronotal collar weak.

Description. FEMALE. Length 4.76–4.88 mm; head length 1.44–1.73 mm; head width 1.82–1.85 mm; forewing length 3.90–4.03 mm.

Colouration. Head and mesosoma very dull metallic greenish blue, nearly brown. Clypeus with apical 2/3 blackish brown. Antenna dark brown, flagellum with ventral surface reddish. Tegula pale translucent amber. Wing membrane subhyaline, venation and pterostigma amber. Legs brown, except tarsi reddish to brownish yellow. Metasoma reddish brown, terga and sterna with apical margins pale translucent brownish yellow.

Pubescence. Dull white. Sparse. Head and mesosoma with moderately sparse woolly hairs (1–1.5 OD), longest on genal beard, metanotum, and mesopleuron (2–2.5 OD). Face without tomentum. Frons and upper paraocular area with moderately dense hairs, most apparent when viewed from below. Pronotal collar without dense tomentum. Propodeum with sparse plumose hairs on lateral and posterior surfaces (2–2.5 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 curved onto ventral surface. Penicillus reduced to a few thick bristles. Metasomal terga with moderately sparse, fine hairs. T1 acarinarial fan visible only as a few appressed lateral hairs. T2–T3 basolaterally and T4 entirely with scattered tomentum. T3–T4 with moderately dense elongate hairs. Sternal hairs, subappressed, not arranged as scopa (2–3 OD).

Surface sculpture. Face weakly imbricate, punctation extremely fine. Clypeus polished, punctation sparse (i=1–3d). Supraclypeal area with punctation sparse (i=1–6d). Lower paraocular and antennocular areas with punctation moderately dense (i=1–1.5d). Upper paraocular area and frons punctation dense (i<d). Ocellocular area punctation dense (i=d). Gena and postgena carinulate. Mesoscutum polished, punctation fine, sparse between parapsidal lines (i=1.5–4d), moderately dense laterad of parapsidal lines (i=1–1.5d) and dense on anterolateral portion (i≤d). Mesoscutellum similar to mesoscutum, punctation sparse (i=1–3d). Axilla punctate. Metanotum weakly imbricate. Preëpisternum and hypoepimeral area imbricate. Mesepisternum dorsal half weakly rugulose, ventral half imbricate. Metepisternum with upper two-fifths weakly carinulate and ventral portion imbricate. Metapostnotum irregularly carinulate. Propodeum with dorsolateral slope imbricate, lateral and posterior surfaces tessellate. Metasomal terga polished except apical impressed areas weakly coriarious, punctation uniformly close (i=1–1.5d), except apical impressed area nearly impunctate.

Structure. Head enormous, very wide (length/width ratio = 0.78–0.82). Eyes subparallel (UOD/LOD ratio = 1.00– 1.02). Labrum enlarged and flattened without distinct basal tubercle, apical process flat and wide without dorsal keel ( Fig. 6 B). Mandible large, scythe-like, without preapical tooth, very narrow, tapering evenly to apex reaching to opposing mandibular base. Clypeus 1/5 below suborbital line, apicolateral margins convergent. Antennal sockets distant (IAD/ OAD = 0.8). Frontal line carinate, ending>2 OD below median ocellus. IOD less than OOD. Median ocellus at upper ocular tangent. Gena huge, one and half times as wide as eye. Hypostomal carinae divergent towards mandible. Pronotal dorsolateral angle acute ( Fig. 181 ). Pronotal ridge angled, uninterrupted. and protrochanter unmodified. Basitibial plate lower carinae absent. Inner metatibial spur pectinate with 3–4 short teeth. Metapostnotum truncate (MMR ratio = 1.41– 1.50), posterior margin weakly angled 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 5.80 mm; head length 1.38–1.58 mm; head width 1.49–1.70 mm; forewing length 4.03 mm.

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

Pubescence. Face with sparse tomentum. Lower paraocular area with dense tomentum obscuring surface. Gena without tomentum. S2–S5 apicolateral portions with sparse plumose hairs (1 OD).

Surface sculpture. Clypeus uniformly punctate (i=1–1.5d). Supraclypeal area with punctation sparse (i=1–3d). Metanotum rugose. Metapostnotum completely rugoso-carinulate. Propodeum with dorsolateral slope rugose. Metasomal terga polished, punctation uniform (i=1.5–2d) except apical impressed areas impunctate.

Structure. Head wide (length/width ratio = 0.93). Eyes convergent below (UOD/LOD ratio = 1.27–1.34). Clypeus 1/ 2 below suborbital tangent, apicolateral margins subparallel. Antennal sockets distant (IAD/OAD> 1.7). Frontal line carinate, ending 2 OD below median ocellus. IOD subequal to OOD. Pedicel shorter than F1. F2 length 1.7–1.8X F1. F2– F10 moderately elongate (length/width ratio = 1.43–1.55). Hypostomal carinae weakly divergent. Metapostnotum moderately elongate (MMR ratio = 1.29–1.35), posterior margin weakly angled onto posterior surface.

Terminalia . S7 with medial lobe wide, acuminate, apex rounded. S8 with apicomedial margin strongly convex. Genital capsule as in Fig. 184 . Gonobase with ventral arms thick, widely separated. Gonostylus small, dorsal setae elongate. Retrorse lobe elongate, weakly attenuated, reflexed apically.

Range. North Carolina, west to Mississippi and Minnesota ( Fig. 185 ). USA: IL, MA, MD, NY, VA, WV.

Paratypes. USA: ILLINOIS: 1Ƥ Hancock Co., N40.3672 W091.4076, 22.viii.2010 (R. Geroff); MARYLAND: 13 Pr. George’s Co., N39.0352 W076.8739, 21.vii.2004 (S. Kolski); 1Ƥ Pr. George’s Co., N39.0568 W076.8143, 2– 3.x.2002 (E.J. Jackson); 4ƤƤ Talbot Co., N38.8 W.076.2833, 7–8.v.2005 (W. Steiner); [PCYU]; 1Ƥ Montgomery Co., N39.085 W77.0067, 5–7.iv.2010 (J. Whitaker); 1Ƥ Talbot Co., N38.8 W.076.2833, 7–8.v.2005 (W. Steiner); [CUIC]; MASSACHUSETTS: 13 Worcester Co., sand pit, 1.6 mi SW of Lake Denison, 1.ix.2006 (M.F. Veit); [PCYU]; NEW YORK: 433 Suffolk Co., Gardiners I., 19.viii.2007 (R.G. Goelet); [AMNH]; VIRGINIA: 1Ƥ Loudoun Co., BRNP, N39.0283 W77.595. 22.viii.2010 (M. Irwin, R. Circe); [CUIC]; WEST VIRGINIA: 1Ƥ Hampshire Co., Capon Bridge, Buffalo Gap Camp, 20.vii.2001 (S. Droege); [PCYU]; 2ƤƤ Hampshire Co., N39.2315 W78.4638, 23.viii.2009 (S.W. Droege); 1Ƥ Hampshire Co., Lehew 16.viii.2011 (S. Droege); 2ƤƤ Hampshire Co., Lehew 17.viii.2011 (S. Droege); 1Ƥ Hardy Co., N39.0942 W78.5615, 1–11.iv.2010 (J. Whitaker); 1Ƥ Randolph Co., N38.8528 W79.5293, 11.iv.2010 (J. Whitaker); [CUIC].

Floral records. ASCLEPIADACEAE : Cynanchum leave , ASTERACEAE : Cirsium , Leucanthemum , Solidago , CORNACEAE : Cornus , SALICACEAE : Salix nigra .

Etymology. The species is named in honour of Jerome Rozen, Jr. for his many studies of cleptoparasitic bees.

Biology. Robertson, 1901: (possible host); Robertson, 1926: (possible host); Michener, 1978: (possible host).

Comments. Uncommon.

Lasioglossum rozeni is believed to be a social parasite or cleptoparasite of nest-building L. ( Dialictus ).

Figures

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

FIGURE 180. Lasioglossum rozeni Gibbs female, (A) lateral habitus, (B) face. Scale bars = 1 mm. (Modified from Gibbs 2010 b).

FIGURE 181. Lasioglossum rozeni Gibbs female, dorsal view of mesosoma. (Modified from Gibbs 2010 b).

FIGURE 182. Lasioglossum rozeni Gibbs male, (A) lateral habitus, (B) face. Scale bars = 1 mm. (Modified from Gibbs 2010 b).

FIGURE 183. Lasioglossum rozeni Gibbs male, dorsal view of mesosoma. (Modified from Gibbs 2010 b).

FIGURE 184. Lasioglossum rozeni Gibbs, new species male terminalia, (A) ventral view, (B) dorsal view. Scale bar = 0.5 mm. (Modified from Gibbs 2010 b).

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