Lasioglossum disclusum Walker, 2025

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 : 57-63

Lasioglossum . ( Enigmalictus ). disclusum ( Cockerell 1914) new status

( Figures 16, 17B, 26A–B, 31A, 42A–B, 43A–B, 44A–B)

Halictus disclusus Cockerell 1914, p. 243 (original description); Cockerell 1919, p. 125 (compare); Hacker 1921, p. 137

(catalogue); Cockerell 1933, p. 308 (redescription), p. 315 (compare); Walker 1995, p. 110 (redescription). Halictus boweni Cockerell 1915, p. 103 (original description); Hacker 1921, p. 135 (catalogue); Cockerell 1933, p. 305

(redescription); Walker 1995, p. 110 (synonymy with H. disclusus ). Halictus pertribuarius Rayment 1935, p. 705 (original description) new synonymy. Lasioglossum (Chilalictus) disclusum — Michener 1965, p. 176 (generic and subgeneric status change). Lasioglossum (Austrevylaeus) pertribuarium — Michener 1965, p. 171 (generic and subgeneric status change).

Diagnosis. Female of L. disclusum can be recognised by the combination of: Body length 6.41 (± 0.51 SD) mm ( Fig. 42A). ITS = 1.15 (± 0.03 SD) mm. Face short (FL/HW ratio 0.76 (± 0.04 SD)). Head and mesosoma black. Metasoma T1–T4 light testaceous coloured, T5–T6 dark red brown ( Fig. 42A). Mesoscutum medially with equally sized punctures, medially with moderately dense punctures (IS = 1–3 PD), inner margins of parapsidal lines with moderately sparse punctures (IS = 2–4 PD), in parapsidal areas with sparse punctures (IS = 3–6 PD), in posterolateral corners with moderately dense punctures (IS = 1–3 PD) and along posterior margin with moderately dense punctures (IS = 1–3 PD) ( Fig. 26B). Metapostnotum striate. Inner metatibial spur denticulate-serrate and oblique with c. 16 teeth laid on top of each other and tooth length not as tall as width of rachis ( Fig. 17B).

Males of L. disclusum can be recognised by the combination of: Body length 6.62 (± 0.13 SD) mm ( Fig. 42B). ITS = 1.08 (± 0.03 SD) mm. Face short (FL/HW ratio 0.79 (± 0.03 SD). Mesoscutum with sparse punctures (IS = 2–3 PD), paraspidal areas with moderate punctures (IS 2–3 PD). Head and mesosoma black ( Fig. 42B). Metasoma T1 dark brown basally, T1 apically, T2–T3 and T4 basally light red brown, T4–T6 dark brown or dark brown, some specimens with metasoma dark brown ( Fig. 42B). Metasoma sterna S4–S5 with weak, lateral tufts (Length of hair: MOW ratio as 1.1 (± 0.03 SD)) ( Fig. 31A). Genitalia with gonostylus:gonocoxite length ratio 0.85 (± 0.02 SD), retrorse lobe present ( Figs. 44A–B).

Comments. Michener (1965) placed Halictus disclusus into Chilalictus most likely as the type of Halictus disclusus is male but placed Halictus pertribuarius into Austrevylaeus as the type of Halictus pertribuarius is female. The male is recognised by the light red brown colouration on metasoma segments T1–T3. Several specimen labels note that males were swarming when collected. Many specimens of this species, in particular males, were collected on Leptospermum . Males showed variation in the colour of the metasoma. In most males, the metasoma is light red brown on T1 apically and T2–T3; however, in some males from Tasmania (e.g. Pelion Hut, Melaleuca, Mt Wellington, Mt Rugby), the metasoma is entirely dark brown. Males of both colour morphs were collected at the same location. Examination of male genitalia between the two-colour morphs showed no difference. Lasioglossum disclusum is like L. exoneuroides and can be distinguished in the female by L. exoneuroides clypeus apically red brown compared to black in L. disclusum . In the male, T1 of L. exoneuroides is entirely light red brown while in L. disclusum T1 is dark brown basally as well as male genitalia characters. Halictus pertribuarius is a junior subjective synonym of Halictus disclusus .

This species is part of a species complex including L. disclusum , L. exoneuroides and L. excelsum but can be separated in the female by: In L. disclusum the clypeus is dark brown to black colour, mesoscutum medially with equally sized punctures, medially with moderately dense punctures (IS = 1–3 PD), inner margins of parapsidal lines with moderately sparse punctures (IS = 3–4 PD), in parapsidal areas with sparse punctures (IS = 3–6 PD), and metasoma T1–T4 light testaceous, T5–T6 dark red brown. In L. excelsum the clypeus dark brown to black colour, mesoscutum medially with equally puncture sized, medially with sparse punctures (IS = 2–6 PD), inner margins of parapsidal lines with moderately dense punctures (IS = 1–2 PD), in parapsidal areas with moderate punctures (IS = 2–3 PD) and metasoma either entirely light red brown or T1–T4 light brown, T5–T6 dark brown. In L. exoneuroides clypeus with apical half light red brown colour, mesoscutum medially diversopunctate, medially with moderately sparse punctures (IS = 2–6 PD), inner margins of parapsidal lines with sparse punctures (IS = 3–6 PD), in parapsidal areas with sparse punctures (IS = 3–6 PD) and metasoma T1–T4 light brown, T5–T6 dark brown. In the male: in L. disclusum metasoma T1 dark brown basally, T1 apically, T2–T3 and T4 basally light red brown, T4–T6 dark brown or metasoma dark brown and metasoma sterna S4–S5 with lateral tufts (MOW:Length of tuft ratio 1.1 (± 0.03 SD)), in L. exoneuroides metasoma T1–T3 light red brown, T4–T6 dark brown and metasoma sterna S4–S5 with lateral tufts (Length of hair:MOW ratio as 0.5 (± 0.03 SD)), in L. excelsum metasoma T1–T3 black basally and brown apically, T4–T6 black and metasoma sterna S4–S5 with lateral tufts (Length of hair:MOW ratio as 1.56 (± 0.03 SD)). The types of L. disclusum and L. boweni were collected at the same location and dates.

This species has a wide elevation preference ranging from over 2,000 m (e.g. Mt Kosciuszko) down to sea level at Dromana. It is the only “weak-veined” species recorded from Australia’s highest elevation at Mt Kosciuszko.

Etymology. Cockerell did not provide a reason for the name Halictus disclusus . However, “disclusus ” is Latin for “separated”. In Cockerell’s 1914 description, he stated that Halictus disclusus was like two other species but gave characters on how Halictus disclusus could distinguished. Rayment (1935, p. 703) described the new species Halictus tribuarius (now a Parasphecodes species). “Per” is Latin for “through or by”. Rayment (1935, p. 703) provided notes on how to distinguish Halictus tribuarius from Halictus pertribuarius so considered they were closely related. The species epithet “boweni ” may be associated with famous naval explorers with ties to Australia, e.g. John Bowen (1780–1827), English Royal Navy officer and colonial administrator. (Gibbs pers. comm. 2024).

Syntype of “ Halictus disclusus ”. AUSTRALIA. Tasmania. ♂; Eaglehawk Neck , Feb 12–March 3, 1913, R . E. Turner, 1913–212. ( BM Type Hym. 17.a.979. NHMUK014024727 , NHMUK) .

Syntype of “ Halictus boweni ”. AUSTRALIA. Tasmania. ♂; Eaglehawk Neck , Feb 12–March 3, 1913, R . E. Turner, 1913–212. (Missing right antenna. BM Type Hym. 17.a.931. NHMUK014024677 , NHMUK) .

Syntype of “ Halictus pertribuarius ”. AUSTRALIA. Victoria. ♀: Grampians, Oct 1928, F.E. Wilson (Missing right mid and hind legs, and left mid and metatarsi. ANIC) .

Additional material examined. (110 specimens, 62 ♀, 48 ♂): AUSTRALIA. New South Wales. (1 ♀) Snowy R , Mt Kosciusko (now Mt Kosciuszko), 4,000 ft (1219 m), 12 Dec 1931, L.F. Graham ( ANIC); (1 ♀) Tin Mine Kosciusko (now Mt Kosciuszko ) district, 4,100 ft (1249 m), 4 Feb 1946 ( AM) .

Victoria. (2 ♂) Mt Hotham—Dargo High Plains area , 9 April 2000, K. Walker, on Hypochaeris radicata (NMV) ; (3 ♀) Grampians , Oct 1928, F.E. Wilson ( NMV); (1 ♀) Halls Gap , Nov 1928, C.B ( NMV); (1 ♀) 12 mls (19 kms) W of Neerim , 5 Jan 1965, A. Neboiss ( NMV); (1 ♀) Dromana , 3 Nov 1931, A. Burns ( NMV); (1 ♀) Olinda , 8 Dec 1929, F.E. Wilson ( NMV); (1 ♂) Mt Eveyln , 19 Jan 1930 ( NMV); (1 ♀) Beech Forest via Colac , 6 Jan 1968, T. Weir ( ANIC); (1 ♀) 6 km E of Warburton , 27 Feb 1976, A. Neboiss ( NMV) .

Tasmania. (1 ♀) 3 km NE by E Wayatinah, 15 Jan 1983, I.D. Naumann & J.C. Cardale (ANIC); (1 ♀) Springs, ~ 750m, Mt Wellington, 11 Nov 1988, P.B. McQuillan, foraging on flowers of Veronica formosa (NMV) ; (1 ♀) Mt Field National Pk, L. Fenton, 13 Jan 1997, A. Hingston, on Cyathodes parvifolia (now Leptecophylla parvifolia ) (NMV); (1 ♀) SW National Pk, (nr Strathgordon), 12 Jan 1997, A. Hingston, on Baeckea leptocaulis (NMV) ; (1 ♀) The Chalet, 1,000 m, Mt Wellington, 4 March 1997, A. Hingston, on Senecio lautus (now Senecio pinnatifolius ) (NMV); (1 ♀) Coffee Creek, Howden, 28 Oct 1996, A. Hingston, on Leucopogon ericoides (NMV) ; (3 ♂) Mt Wellington, ~ 900 m, 2–11 April 1997, A. Hingston, on Correa lawrenciana (NMV) ; (2 ♀) Tasmania 10 Feb 1953 (one specimen labelled “ Allotype ” (red label) and “ Halictus disclusus ” in Rayment’s handwriting, ANIC); (1 ♀) 33 mls (53 kms) E. Queenstown, 2 Jan 1969, E.M. Exley, on Eucalyptus sp. (QM); (1 ♀) Murchison Hwy, 31 Dec 1968, E.M. Exley, on Eucalyptus (QM) ; (1 ♀) NE Slope Mt Bowes, 12 Feb 1965.A. Neboiss (NMV): (1 ♀) 9 mls (14 kms) E Strahan, 1 Jan 1969, E.M. Exley, Bursaria spinosa (QM) ; (4 ♀) Mt Wellington, 4 March, 14 Oct, 2 Dec 1917, G.H. Hardy (QM); (2 ♀) Tarraleah, 29 Nov 1970, K.R. Norris (ANIC); (1 ♀) 12 km NNE Bronte Park, 20 Jan 1983, I.D. Naumann & J.C. Cardale ex. yellow tray (ANIC); (1 ♀) 4 km E Rosebery, 16 Jan–1 Feb 1983, I.D. Naumann & J.C. Cardale malaise/ethanol (ANIC); (1 ♀) 6 km W Miena, 2 Jan 1983, I.D. Naumann & J.C. Cardale (ANIC); (20 ♂) Melaleuca , 12 Feb 1988, K. Walker, on Leptospermum (NMV) ; (4 ♀) Melaleuca, Bathurst Harbour , 12–17 Feb, 3–7 Dec 1990, I.D. Naumann, on Eucalyptus nitida (ANIC) ; (3 ♂) Melaleuca, Bathurst Harbour , 11–15 April 1991, J.A. Berry (ANIC); (1 ♂) Florentine Valley, 20 km W Maydena, 9 Feb 1988, K. Walker, on Leptospermum (NMV) ; (3 ♂) Cradle Mountain, 7 March 1989, K. Walker, on Leptospermum rupestre (NMV) ; (1 ♂) Lake Dobson, 31 Jan 2001, K. Hingston, on Leucopogon sp. (NMV); (8 ♂) Mt Rugby, Bathurst Harbour, 15 Feb 1990, I.D. Naumann, swarm over eucalypt (ANIC); (17 ♀, 4 ♂) Pelion Hut, 3 km S Mt Oakleigh, 28–30 Nov 1990, I.D. Naumann, yellow trays (ANIC); (2 ♀) Celery Top Island, Bathurst Harbour, 3 Dec 1990 – 15 Jan 1991, Nielsen & Edwards, malaise trap (ANIC); (6 ♀, 1 ♂) Great Lake, 6 Feb 1953 (ANIC); (1 ♂) Lake St Clair, 10 April 1955 (ANIC); (1 ♀) Breona, 27 Jan 1960, F.J.D. McDonald (ANIC).

Redescription of male, female described for first time

Female. Body length 6.41 (± 0.51 SD) mm. ITS = 1.15 (± 0.03 SD) mm. Head length 1.68 (± 0.06 SD) mm. Head width 1.76 (± 0.21 SD) mm. Wing length 5.49 (± 0.76 SD) mm. (n=10).

Colouration. Head and mesosoma black. Clypeus dark brown to black. Labrum brown. Mandible brown basally, light brown medially with reddish-brown apically. Flagellum dark brown dorsally and ventrally. Pronotal lobe dark brown. Tegula reddish-brown. Wing membrane hyaline, faintly dusky, veins with subcosta brown, otherwise honey coloured. Legs brown, darker brown basally with colour lightening apically. Metasoma T1–T4 light testaceous coloured, T5–T6 dark red brown coloured. Body setae white. Wing hairs pale. ( Figs. 26A, 26B, 42A, 43A).

Pubescence. Head with frons, vertex and gena with sparse cover of erect hair, paraocular area with dense cover of appressed hair ( Fig. 2). Pronotal lobe almost bare, posterior margin of spiracle cover with dense layer of short, appressed hair. Mesoscutum with sparse cover of short, erect hair, a few more hairs along posterior margin ( Fig. 26B). Mesepisternum with weak cover of erect hair. Lateral surface of propodeum with moderate cover of elongated, branched, erect hair, posterior surface with spare cover of erect hair. Metafemoral scopa with dense plumose hairs ( Fig. 42A). T1–T4 dorsally almost bare, some hairs laterally, T5–T6 with sparse cover of short setae.

Surface sculpture. Clypeus shining and smooth on anterior half, dull with imbricate pattern on basal half, apical half punctures large, deeply impressed, irregularly with moderately sparse punctures (IS = 2–3 PD), basal half with smaller moderately sparse puncturesd (IS = 2–3 PD). Supraclypeal area dull, with imbricate pattern, medially impunctate, laterally with moderately sparse punctures (IS = 2–3 PD. Paraocular area smooth and impunctate. Frons dull, with minute crowded punctures (IS = 0 PD) with rim of each puncture raised and forms part of adjoining puncture ( Fig. 26A). Vertex impunctate with imbricate pattern. Gena strigulate with parallel lines. Tegula shining, impunctate on apical half, basal half substrigulate, with minute dense punctures (IS = 0–1 PD). Mesoscutum dull, entirely covered with imbricate pattern, equally puncture sized, medially with moderately dense punctures (IS = 1–3 PD), inner margins of parapsidal lines with moderately sparse punctures (IS = 2–4 PD), in parapsidal areas with sparse punctures (IS = 3–6 PD), in posterolateral corners with moderately dense punctures (IS = 1–3 PD) and along posterior margin with moderately dense punctures (IS = 1–3 PD) ( Fig. 26B). Mesoscutellum dull, imbricate, with dense punctures (IS = 1 PD), laterally with moderately dense punctures (IS = 1–2 PD). Metanotum dull, impunctate, imbricate.Metapostnotum striate, medially striae reaching about halfway to posterior margin, laterally striae reaching dorsolateral slope, posterior margin rounded, sculpture shining but imbricate. Propodeum lateral face dull, imbricate and impunctate, posterior face dull, imbricate and impunctate, lateral carina basally only, oblique carina absent ( Fig. 43A). Preëpisternum weakly scabrous. Mesepisternum coarsely imbricate and impunctate. Metepisternum dull, imbricate and impunctate. Hypoepimeron inflated, dull, glabrous, weakly imbricate and impunctate. T1 dorsal surface shining, appears impunctate, but with sparse, minute punctures (IS => 6 PD). T2 shining, with similar punctures to T1.

Structure. Face short (FL/HW ratio 0.76 (± 0.04 SD)). Eyes convergent below [UOD/LOD ratio 1.05 (± 0.03 SD)]. Median ocellus width/ocellocular distance ratio [MOW:OOD ratio 0.58 (± 0.2 SD)]. Clypeus extends ~53% below suborbital tangent, clypeus length/width ratio 0.49 (± 0.08 SD). Clypeus with apicolateral denticles. Gena narrower than eye. Mandible short, not reaching opposing clypeal angle. Protibial spur with apical serrations longer than length to width of malus. Inner metatibial spur denticulate-serrate and oblique with c. 16 teeth laid on top of each other and tooth length not as tall as width of rachis ( Fig. 17B). Distance between parapsidal line (at the starting point) 0.91 (± 0.04 SD) mm. Pronotal angle rounded and weakly projected. Mesoscutum length/width (widest point) ratio 0.77 (± 0.05 SD). Mesoscutum/mesoscutellum length ratio 2.83 (± 0.18 SD). Mesoscutellum/metanotum length ratio 1.13 (± 0.14 SD). Stigma medium, 0.79 mm long, 0.22 mm wide (ratio ~3.60 (± 0.07 SD)), margin in marginal cell convex, marginal cell 1.27 mm long, 0.34 mm wide, free portion about 2.3X that subtended by submarginal cells (0.74 mm: 0.38 mm). 1m-cu distinctly inside the second submarginal cell and separated from 1rs-m. Stigma perpendicular goes about middle of third submarginal cell.

Male. Body length 6.62 (± 0.13 SD) mm. ITS = 1.08 (± 0.03 SD) mm. Head length 1.63 (± 0.05 SD) mm. Head width 1.71 (± 0.03 SD) mm. Wing length 4.77 (± 0.14 SD) mm. (n=10).

Colouration. Head and mesosoma black. Clypeus basally brown, apically yellow white. Labrum dark brown to black. Mandible dull yellow–brown basomedially and dark reddish brown apically. Flagellum dark brown to black dorsally, dark brown ventrally. Pronotal lobe dark brown. Metasoma T1 dark brown basally, T1 apically, T2–T3 and T4 basally light red brown, T4–T6 dark brown or metasoma dark brown. Fore, mid and hind legs coxa, trochanter and femur and hind leg tibia dark brown to black, remainder of legs light yellow brown. Tegula dark brown to black. Wing membrane hyaline, veins with subcosta brown, otherwise light brown to pale amber. Wing hairs pale. ( Fig. 42B, 43B).

Pubescence. Body hair colour brownish white. Frons with sparse cover of erect setae, dense setae between antennal bases, moderate cover of appressed hair in paraocular area. Clypeus dorsal surface almost glabrous, with sparse erect hairs, laterally with denser long setae ( Fig. 43B). Gena with sparse cover of erect setae. Pronotal lobe almost glabrous, some denser hair around posterior margin of spiracle cover. Sparse cover of hair on preëpisternum and mesepisternum. Metanotum and mesoscutum with sparse cover of short, erect hairs. T1–T6 with sparse cover of short, erect hair, a few long hairs on margins of tergites. Metasoma sterna S4–S5 with weak, lateral tufts (length of hair ratio:MOW ratio as 1.1 (± 0.03 SD)) of backwardly pointing plumose ( Fig. 31A).

Surface sculpture. Clypeus with a dull sheen, apical half with moderately sparse punctures (IS = 2–4 PD), basal half with moderately dense punctures (IS = 1–3 PD) with imbricate sculpture, diversopunctate between apical and basal halves. Supraclypeal area smooth and dull, surface impunctate. Paraocular area smooth and shining, impunctate. Frons with minute, crowded to dense punctures (IS = 0 PD). Vertex weakly rugulose across vertex surface. Gena weakly rugulose. Tegula shining, impunctate across apical half, with dense (IS ≤ 1 PD) to moderate punctures (IS = 1–2 PD) basally. Mesoscutum dull, medially and laterally with dense punctures (IS ≤ 1 PD). Mesoscutellum dull, with crowded punctures medially, dense punctures laterally (IS ≤ 1 PD). Metanotum dull, scabriculous. Metapostnotum striate with striae almost reaching posterior margin, sculpture shining. Preëpisternum and mesepisternum imbricate and with sparse punctures (IS = 2–3 PD). Metepisternum dull and striate. Propodeum lateral face scabriculous, posterior face imbricate-scabriculous. T1 dorsal surface shining, medially with dense punctures (IS ≤ 1 PD) and moderately dense punctures (IS = 1–3 PD) laterally with minute punctures. T2 shining, with moderately sparse punctures (IS = 2–4 PD).

Structure.Face short (FL/HW ratio 0.79 (± 0.03 SD). Clypeus projecting ~40% below suborbital tangent, clypeus length/width ratio 0.49 (± 0.04 SD). Flagellomeres, except F1, elongate, F2 equal to F1 and pedicel combined. F2: F1+pedicel length ratio 1.00 (± 0.03 SD). F2:F1 length ratio 2.14 (± 0.02 SD). F2 length/width ratio 1.50 (± 0.04 SD). F9 length/width ratio 1.38 (± 0.09 SD). Eyes strongly convergent below (UOD/LOD ratio 1.48 (± 0.03 SD). Gena narrower than eye. Mandible short, not reaching opposing clypeal angle. Pronotal angle rounded. Mesoscutum length/width ratio 0.77 (± 0.02 SD). Mesoscutum/mesoscutellum length ratio 2.50 (± 0.04 SD). Mesoscutellum/ metanotum length ratio 1.67 (± 0.03 SD). Propodeum lateral and oblique carinae absent.

Genitalia.Gonobase flat at bottom, tapered basally, gonobase:gonocoxite length ratio 0.7 (± 0.03 SD),gonostylus: gonocoxite length ratio 0.85 (± 0.02 SD), gonostylus apically with elongated setae, inner margin setae curved at tip and setae from each gonostylus extends beyond midway between gonostyli, penis valve inner margin with setae, retrorse lobe present, long and broad (length 2 times width), not reaching gonobase, densely setose with elongated setae, length of setae equal to or greater than width of retrorse lobe, setae parallel, at right angles to retrorse lobe, setae curved at tip ( Figs. 44A–B).

Range. Occurs in New South Wales, Victoria and Tasmania ( Fig. 16).

Flight period. This species has been collected in all months of the year except June, July, August and September ( Table 1).

Floral hosts. ASTERACEAE : Hypochaeris radicata . ERICACEAE : Leptecophylla parvifolia , Leucopogon

sp. Leucopogon ericoides . MYRTACEAE : Baeckea leptocaulis , Eucalyptus , Eucalyptus nitida , Leptospermum , Leptospermum rupestre . PITTOSPORACEAE : Bursaria spinosa . PLANTAGINACEAE : Veronica formosa , RUTACEAE : Correa lawrenciana .