Lasioglossum

Walker, Kenneth L., 2025, The “ weak-veined ” Lasioglossum in Australia, New Zealand and West New Guinea, with descriptions of three new subgenera (Hymenoptera: Apoidea: Halictidae), Zootaxa 5651 (1), pp. 1-94 : 82-88

Lasioglossum . ( Hemihalictus ). oblongulum . new species urn:lsid:zoobank.org:act:59C1412E-756E-497F-AE9A-2BD36F3A23B9

( Figures 55A–C, 56A–B, 57, 58)

Diagnosis. The female of L. oblongulum can be recognised by the combination of: Body length 7.58 mm. ( Fig. 55A). ITS = 1.20 mm. Face long (FL/HW width ratio 1.25). ( Fig. 55B–C). Head, mesosoma and metasoma dark brown ( Fig. 55A). Pronotum enlarged, lateral angle rounded ( Fig. 56A). Mesoscutum shining, strongly produced forward apicomedially, equally puncture sized, medially with moderate punctures (IS = 1–3 PD), laterad of medially area with sparse punctures (IS = 2–5 PD), inner margins of parapsidal lines with moderately dense punctures (IS = 2 PD), in parapsidal areas with moderate punctures (IS = 1–2 PD), in posterolateral corners with moderate punctures (IS = 1–3 PD) and along posterior margin with moderately dense punctures (IS = 1–2 PD) ( Fig. 56A). Metapostnotum striate across entire surface ( Fig. 56B). Propodeum lateral carina present but incomplete, basally only, oblique carina absent ( Fig. 56B). Inner metatibial spur pectinate with six, erect, apically rounded teeth, length of teeth equal to or greater than width of rachis ( Fig. 57).

Comments

The female of L. (Hemihalictus) oblongulum has a noticeably elongated face that is longer than wide (Face length/ width ratio 1.25, Figs. 55B–C). There are many northern hemisphere “weak-veined” Lasioglossum species in which females display an elongated face. Here, four species have been selected to demonstrate the range of HL/HW ratios to better understand the HL/HW ratio found on L. (Hemihalictus) oblongulum . Lasioglossum (Rostrohalictus) longirostre ( Morawitz, 1876) —a halictine bee from Middle East to Central Asia ( China (Xinjiang), Greece, Turkey, Armenia, Azerbaijan,Georgia, Iran, Lebanon, Israel, Kazakhstan, Kyrgyzstan, Uzbekistan, Tajikistan andAfghanistan ( Murao et al. 2017; Nui et al. 2020; images available at Pauly 2016a). Lasioglossum (Hemihalictus) punctatissimum ( Schenck 1853) —a halictine bee from the Palaearctic region ( Ireland to the Urals, from Morocco to Iran, north to Finland) ( Lhomme 2020; Pauly 2016b; images available at Pauly 2016b). Lasioglossum (Hemihalictus) buccale (Pérez, 1903) —a halictine bee from the Palaearctic region ( Austria, Bulgaria, France, Italy, Germany, Macedonia, Spain, Switzerland, Ukraine — Ebmer 2003, GBIF 2025) and recently introduced to the Americas ( Canada, Oregon, Washington, and west of British Columbia — Hatten et al. 2024; images available at Engler et al. 2024). And, L. (Hemihalictus) ovaliceps ( Cockerell 1898) —a halictine bee from the Nearctic region (Alaska, Canada, USA and New Mexico — Sheffield & Heron 2018, Hettiarachchi 2024; images available at Engler et al. 2024). There are also several non-metallic Dialictus species with an elongated face ( Gardner & Gibbs 2020).

The head length to width (HL/HW) ratios for females of these four species are: L. buccale HL /HW = 1.09, L. longirostre HL /HW = 1.48, L. oblongulum HL /HW = 1.25, L. ovaliceps HL /HW = 1.10 and L. punctatissimum HL /HW = 1.08.

Warncke (1975) erected two monotypic subgenera for two of northern hemisphere species with a female elongated face. Rostrohalictus Warnacke 1975 has a remarkably elongated head, especially in the male, facilitated by an extended malar area (malar area 0.2 times length of the compound eye in the female and malar area almost equal to length of eye in male—Nui et al. 2020) to accommodate Halictus longirostris Morawitz 1876 . The second subgenus, Puncthalictus Warncke 1975 , was erected to accommodate Hylaeus punctatissimus Schenck 1853 , which also has an elongated head but to a lesser degree than Halictus longirostris as the malar area is linear ( Zhang et al., 2022). Ebmer (1971) placed L. buccale into Evylaeus, Pesenko 2007a placed L. buccale into the Warncke’s Puncthalictus which was synonymised with Hemihalictus (Gibbs et al. 2013). Michener 1951 recombined Halictus ovaliceps into Evylaeus , which was followed by Hurd (1979) and Moure & Hurd (1987), but was later recombined into Hemihalictus (Hettiarachchi 2024; Hettiarachchi & Gibbs 2024).

There have been several changes to the status of the two Warncke (1975) subgenera and both species remain valid. Ebmer (1974) placed L. longirostre into Evylaeus and placed L. punctatissimus into the ‘carinaless’ Evylaeus Ebmer (1976 , 1997). Aliev et al. (2005) placed Lasioglossum longirostris into the genus Evylaeus while Pesenko (2007b) placed Halictus longirostris into the ‘carinaless’ Evylaeus (Rostrohalictus) . Murao & Tadauchi (2007) placed both Puncthalictus and Rostrohalictus into Evylaeus . Michener (2007) synonymised Puncthalictus and Rostrohalictus with Dialictus while Pauly (2016a, b) transferred both species into Evylaeus . Gibbs et al. (2013) synonymised Puncthalictus and Rostrohalictus with Hemihalictus based on morphology. Murao (2017b) placed Puncthalictus and Rostrohalictus with Hemihalictus . Lhomme et al. (2020) placed L. punctatissimus into Evylaeus . Finally, Zhang et al. (2022) conducted a molecular phylogenetic analysis and resurrected Rostrohalictus from synonymy as a valid subgenus of Lasioglossum .

Lasioglossum oblongulum does not align with Evylaeus as the head is longer than wide ( Fig. 55B) ( Evylaeus head is wider than long), the female inner metatibial spur teeth are erect and pectinate ( Fig. 57) ( Evylaeus female inner metatibial spur teeth are finely oblique and denticulate-serrate), and the length of the inner metatibial spur teeth are as long as or longer than width of the spur rachis ( Evylaeus female inner metatibial spur teeth are not long as the width of the rachis) (Gibbs et al. 2013).

The female linear malar area of L. oblongulum is like the linear malar area of L. (Evylaeus) punctatissimus but differs as: length of the face (HL/HW ratios as L. oblongulum new species 1.25, and L. punctatissimum 1.08), and differ in the sculpture patterns on the head, mesosoma and metasoma ( Pauly 2016b).

Lasioglossum oblongulum also does not align with Rostrohalictus as the malar area is linear ( Figs. 55B–C) rather than elongated as found L. (Rostrohalictus) longirostre and the female inner metatibial spur teeth in L. oblongulum are pectinate and the teeth as long or longer than the spur rachis ( Fig. 57) while in L. (Rostrohalictus) longirostre the female inner metatibial spur teeth are finely serrate and less than width of spur rachis ( Pauly 2016a). The propodeum in L. (Rostrohalictus) longirostre female lacks a lateral carina but does have a distinct oblique carina (Nui et. al. 2020) while L. oblongulum lacks both lateral and oblique carinae ( Fig. 56B).

Lasioglossum oblongulum does not align with Sphecodogastra as the propodeum lateral carina is not complete, the oblique carina is absent ( Fig. 56B) and the metatibial scopa is fully developed ( Fig. 55A). Sphecodogastra propodeum lateral carina is complete and oblique carina is present, and if carina weak then metatibial scopa modified and reduced to row of hairs) but both have pectinate female inner metatibial spurs (Gibbs et al. 2013; Murao 2021; Hettiarachchi 2024).

Lasioglossum oblongulum best aligns with Hemihalictus . The body colour is non-metallic dark brown, head is longer than wide, propodeum lateral carina is weak and incomplete, oblique carina is absent and female inner metatibial spur is pectinate ( Fig. 57). (Gibbs et al. 2013; Murao 2021; Gardner 2023; Hettiarachchi 2024; Hettiarachchi & Gibbs 2024).

Etymology. The species named “oblongulum ” is from the Latin word “oblongus” meaning “longer than wide”. An appropriate translation would be the “elongated” and refers to the face length.

Holotype of “ Lasioglossum oblongulum ”. WEST NEW GUINEA. VOGELKOP. ♀: Kebar Valley , W of Manokwari, 550 m, 4–31 Jan 1962. L.W. Quate collector. (Specimen glued to card, right forewing detached but glued to card, missing left metatibia and metatarsi. BPBM).

Description

Female (Holotype). Length 7.58 mm. ITS = 1.20 mm. Head length 1.83 mm. Head width 1.22 mm. Wing length 4.87 mm. (n=10).

Colouration. Head, mesosoma and metasoma dark brown. Clypeus and supraclypeal area brown, frons dark brown. Labrum almost black. Mandible dark red brown basally and medially with lighter reddish brown apically. Flagellum light brown. Pronotal lobe dark brown. Tegula dark brown. Wing membrane hyaline, faintly dusky, veins with subcosta brown, otherwise honey coloured. Legs brown to light brown. Body setae white. Wing hairs light brown. ( Figs. 55A–C, 56A–B, 57).

Pubescence. Head with frons and vertex almost glabrous, lower frons with sparse cover of semi-erect hair, paraocular area with some long, sparse hairs. and vertex with sparse cover of semi-erect hair, genae with sparse cover of long, erect hair ( Figs. 55A–C). Pronotal lobe with a cover of short, erect, plumose hair, posterior margin of spiracle cover with dense layer of short, appressed hair ( Fig. 55A). Mesoscutum almost glabrous ( Fig. 56A). Mesepisternum with sparse cover of erect, plumose hair. Lateral surface of propodeum with sparse cover of short, appressed hair and moderate cover of long, branched hair ( Fig. 56B), posterior surface with spare cover of erect hair ( Fig. 56B). Metafemoral scopa with dense plumose hairs ( Fig. 55A). T1–T3 dorsally almost bare, small area of tomentum basolaterally on T2, T4–T6 with sparse cover of short setae ( Fig. 55A).

Surface sculpture. Clypeus shining and smooth across entire surface, apical half with large, deeply impressed, irregularly moderately sparse punctures (IS = 2–3 PD), basal half with smaller, rounded, moderately sparse punctures (IS = 1–3 PD). Supraclypeal area smooth and shining with sparse punctures (IS = 3–6 PD). Paraocular area smooth and shining with sparse punctures (IS = 3–6 PD). Frons dull, lower frons with minute, crowded punctures (IS = 0 PD) with rim of each puncture raised and forms part of adjoining puncture, upper frons with separated, dense punctures (IS = 1–2 PD). Vertex smooth and shining with minute, moderate punctures (IS = 2–4 PD). Gena strigulate with parallel lines ( Figs. 55B–C). Tegula shining, impunctate. Mesoscutum shining, strongly produced forward apicomedially, equally puncture sized, medially with moderate punctures (IS = 1–3 PD), laterad of medial area with sparse punctures (IS = 2–5 PD), inner margins of parapsidal lines with moderately dense punctures (IS = 2 PD), in parapsidal areas with moderate punctures (IS = 1–2 PD), in posterolateral corners with moderate punctures (IS = 1–3 PD) and along posterior margin with moderately dense punctures (IS = 1–2 PD) ( Fig. 56A). Mesoscutellum smooth and shining, almost impunctate, with a few punctures along midline. Metanotum dull, impunctate, imbricate. Metapostnotum striate across entire surface, medially striae extend just short of posterior margin, laterally striae reaching dorsolateral slope, surface with an imbricate sculpture pattern ( Fig. 56B). Propodeum lateral face dull, imbricate and impunctate, posterior face dull, imbricate and impunctate, lateral carina present but incomplete, basally only, oblique carina absent ( Fig. 56B). Preëpisternum and mesepisternum scabrous. Hypoepimeron inflated, smooth, shining, almost glabrous and impunctate ( Fig. 55A). Metepisternum shining, striate more so dorsally and impunctate. T1–T2 dorsal surface shining, impunctate.

Structure. Face long (FL/HW width ratio 1.25). Eyes convergent below [UOD/LOD ratio 1.38]. Median ocellus width/ocellocular distance ratio [MOW:OOD ratio 0.71]. Clypeus extends greater than 50% below suborbital tangent, clypeus length/width ratio 0.67. Clypeus flat and rounded apically, apicolateral denticles absent ( Fig. 55B). Gena narrower than eye ( Fig. 55C). Mandible long, reaching opposing clypeal angle, preapical tooth small. Protibial spur without extension or apical serrations but rather elongated setae. Inner metatibial spur pectinate with six, erect, apically rounded teeth, length of teeth equal to or greater than width of rachis ( Fig. 57). Distance between parapsidal line (at the starting point) 0.77 mm. Pronotum enlarged, lateral angle rounded ( Fig. 56A). Mesoscutum length/width (widest point) ratio 0.84. Mesoscutum/mesoscutellum length ratio 2.93 (± 0.13 SD). Mesoscutellum/metanotum length ratio 1.45. Stigma medium, 0.74 mm long, 0.29 mm wide (ratio ~2.55), margin in marginal cell convex, marginal cell 1.29 mm long, 0.48 mm wide, free portion about 2.1 times that subtended by submarginal cells (0.86 mm: 0.41 mm). 1m-cu distinctly inside the second submarginal cell and separated from 1rs-m. Stigma perpendicular goes about middle of third submarginal cell.

Male. Unknown.

Range. Occurs in the Kebar Valley in West Papua ( Indonesia) ( Fig. 58). The Kebar Valley ( Indonesian : Lembah Kebar ) is found in the north central region of the Bird’s Head Peninsula in the province of Southwest Papua. Elevations in the valley range from 500 m to 1,400 m. The valley is located 130 km west of Manokwari .

Floral hosts. None recorded.

Summary

This paper continues to resolve the “nomenclatural chaos” called the Lasioglossum complex. Michener (1965) placed six Australian “weak-veined” Lasioglossum species into Austrevylaeus which he erected for the single known New Zealand species— L. sordidum . Michener’s placement was tentative due to differences he noted between the New Zealand and Australian “weak-veined” faunas on the shape of the female inner metatibial spur and he lacked males for any of the Australian species. The New Zealand Austrevylaeus species are amongst the most common halictid bee collected with Donovon (2007) recording 7,231 specimens for the three species. The Australian “weak-veined” specimens are infrequently collected with only 459 specimens for the 11 known species.

Previous revisions of Australian Lasioglossum ( Walker 1995; Walker 2022a) were able to associate females of “weak-veined” species to species originally described from the male only (e.g. L. blighi , L. contaminatum and L. disclusum ). Male genitalia examination showed the Australian “weak-veined” fauna differs from the New Zealand “weak-veined” fauna and that three species-groups were evident which led to the designation of three new subgenera— Cnephalictus , Enigmalictus and Evyloides .

The “weak-veined” New Zealand fauna consists of three species— L. (Austrevylaeus) mataroa , L. (Austrevylaeus) maunga and L. (Austrevylaeus) sordidum . The Australian “weak-veined” fauna consists of 11 species— L. (Cnephalictus) amber , L. (Cnephalictus) bernhardti , L. (Enigmalictus) blighi , L. (Cnephalictus) contaminatum , L. (Enigmalictus) disclusum , L. (Enigmalictus) excelsum , L. (Enigmalictus) exoneuroides , L. (Evyloides) ewarti , L. (Cnephalictus) lorienae , L. (Enigmalictus) melanurus and L. (Enigmalictus) rufibasis .

The New Zealand species occur in both the north and south islands, and L. sordidum occurs also on the three Kings Islands, while the Australian fauna is found in eastern Australian coastal areas and the SW corner of Western Australia with no species found in areas receiving under 500 mm of annual rainfall such as the dry interior of Australia.

A comparison between the floral visitation records of the Australian and New Zealand “weak-veined” faunas shows the 11 Australian “weak-veined” Lasioglossum species recorded floral visitation to 23 plant families and 38 plant genera with the most records on Myrtaceae . The three New Zealand “weak-veined” species recorded floral visitations to 59 plant families and 112 plant genera with the most records on Asteraceae . All three New Zealand species are polylectic foragers.

The three new Australian subgenera have different floral and habitat preferences. Cnephalictus was not recorded visiting Myrtaceae , which is unsurprising as all species in this subgenus occur in rainforests or wet sclerophyll forests. These species appear to be oligolectic and have floral visitation records from six plant families and six genera. Enigmalictus bees are more generalist and polylectic and have floral visitation records from 16 plant families and 31 genera. This subgenus occurs in more typical Mediterranean habitats and was recorded throughout the 500 mm rainfall isohyet areas in both southern eastern and Western Australia. This is the only Australia “weak-veined” subgenus to occur at high altitudes over 2,000 m. Evyloides appears to be monolectic with floral visitation records from one plant subspecies and is known from a single area in North Queensland. The sex ratio of collected specimens suggests this may be Australia’s only Halictidae with primitive eusociality. Due to the limited distribution ranges of several “weak-veined” species, they are “short-range” endemics worthy of conservation efforts and at least L. bernhardti and L. ewarti should be placed on a threatened species list as they are each known from a single area.

A single female new species of a “weak-veined” Lasioglossum was found in West Papua ( Indonesia)— L. oblongulum . This specimen has an elongated head like many Northern Hemisphere “weak-veined” species with elongated heads. Diagnostic characters place the species in the subgenus Hemihalictus .