Lasioglossum melanurus 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 : 72-73

Lasioglossum . ( Enigmalictus ). melanurus ( Cockerell 1919) new status

( Figures 16, 28C–D, 50A–C)

Halictus melanurus Cockerell, 1919, p. 125 (original description); Hacker, 1921, p. 140 (catalogue); Cockerell, 1930, p. 144 (type depository); Cockerell, 1933, p. 315 (redescription).

Lasioglossum (Austrevylaeus) melaurum — Michener, 1965, p. 171 (generic and subgeneric status change).

Diagnosis. Females of L. melanurus can be recognised by the combination of: Body length 4.50 (± 0.55 SD) mm ( Fig. 50A). ITS = 0.79 (± 0.05 SD) mm. Face short (FL/HW ratio 0.71 (± 0.04 SD)). Head and mesosoma black ( Figs. 50A–B). Metasoma T1 dark brown basally, light brown apically, T2–T6 dark brown or entirely light brown ( Fig. 50A). Mesoscutum medially with equally sized punctures, with moderate to sparse punctures (IS = 1–6 PD), inner margin of parapsidal lines with moderately sparse punctures (IS = 2–4 PD), in parapsidal areas with moderately dense punctures (IS = 1–4 PD), in posterolateral corners with moderately sparse punctures (IS = 2–4 PD) and along posterior margin with moderately sparse punctures (IS = 2–3 PD) ( Fig. 28C). Metapostnotum anastomosingly rugulose, Propodeum lateral and oblique carinae weakly present ( Fig. 28D). Inner metatibial spur minutely denticulate with three small, rounded and separated teeth less than one third width of rachis.

Comments. Lasioglossum melanurus is the only “weak-veined” Lasioglossum species recorded from Western Australia and is one of our smaller Australian Lasioglossum species. The type specimen is uniformly coloured light brown and is presumed to be a callow specimen—see type images at USNM 2024 URL). This species is known from only seven specimens and is restricted to the SW corner of Western Australia. It is a “short-range endemic” worthy of significant conservation efforts.

The suffix “-urus” is a Latinized Greek noun meaning “tail” which would make this name indeclinable so the species name should remain “melanurus ” in combination with Lasioglossum rather than as Michener 1965 changed the name to “melanurum”.

Etymology. Cockerell did not provide a reason for the name Halictus melanurus . However, the first part of the name “melan” is Greek for “black” and the suffix “-urus” is a Latinized Greek noun meaning “tail”. An appropriate translation would be “black-tailed” which matches Cockerell’s (1919, p. 125) description of the metasoma being ‘yellowish-ferruginous’ on the first half and ‘fuscous, almost black’ beyond that.

Syntype of “ Halictus melanurus ”. AUSTRALIA. Western Australia. ♀: York, O.H. Sarguit ( USNM Type No: 23191. Specimen glued to card, metasoma detached but glued to card, missing right hind tibia and metatarsi and left hind metatarsi. USNM Number: USNMENT01932610, USNM) .

Additional material examined. (6 ♀ specimens) AUSTRALIA. Western Australia: (1 ♀) Stirling Range , 17 Oct 1974, C.A. & T . F. Houston, on Lambertia (SAM) ; (1 ♀) 24 km SW Nannup , 2 Oct 1975, K.A. Spencer ( WAM, 87/548); (1 ♀) Bunbury, 21 Dec 1956, A. Snell (missing metasoma, NMV); (2 ♀) 34 km SE Waroona, 9 Nov 1989, K.L. Walker, on Calytrix (NMV) ; (1 ♀) Walpole-Nornalup Nat Park, 9 Oct 1970, D.H. Colless ( ANIC) .

Redescription of female

Female. Body length 4.50 (± 0.55 SD) mm. ITS = 0.79 (± 0.05 SD) mm. Head length 1.16 (± 0.06 SD) mm. Head width 1.30 (± 0.24 SD) mm. Wing length 3.30 (± 0.45 SD) mm. (n=4).

Colouration. Head black except clypeus and paraocular area light brown to brown. Labrum light brown. Mandible dark brown basally, medially light brown and apex dark red brown. Flagellum brown dorsally and light brown ventrally. Pronotal lobe light brown. Tegula light yellow brown. Mesosoma with mesoscutum black and mesoscutellum, metanotum, metapostnotum and propodeum brown or mesosoma entirely brown. Wing membrane hyaline, faintly dusky, veins with subcosta brown, otherwise honey coloured. Legs light brown. Metasoma T1 dark brown basally, light brown apically, T2–T6 dark brown or entirely light brown. Body setae white. Wing hairs pale. ( Figs. 28A–B, 50A–C).

Pubescence. Head with frons, vertex and gena with sparse cover of erect hair, paraocular area with a light cover of appressed hair ( Fig. 50B). 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. 28C). 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 ( Fig. 28D). Metafemoral scopa with dense plumose hairs ( Fig. 50A). T1–T4 dorsally almost bare, some hairs laterally, T5–T6 with sparse cover of short setae.

Surface sculpture. Clypeus apical half smooth with a dull sheen, basal half dull with imbricate pattern, apical half with large, deeply impressed, irregularly spaced moderate punctures (IS = 1–2 PD), basal half with smaller moderately sparse punctures (IS = 1–3 PD). Supraclypeal area dull, with imbricate pattern, with small moderate punctures (IS = 1–2 PD. Paraocular area smooth, shining and impunctate. Frons dull, basally with shallow, dense punctures (IS <1 PD), apically with minute scabriculous sculpture ( Fig. 50B). Vertex impunctate with weak imbricate pattern. Gena with moderately dense imbricate–puncture pattern (IS = 1–2 PD).Tegula smooth and shining. Mesoscutum with a dull sheen, entirely covered with imbricate pattern, medially with equal sized punctures, with moderate punctures (IS = 1–4 PD), inner margin of parapsidal lines with moderately sparse punctures (IS = 2–4 PD), in parapsidal areas with moderately dense punctures (IS = 1–4 PD), in posterolateral corners with moderately sparse punctures (IS = 2–4 PD) and along posterior margin with moderately sparse punctures (IS = 2–3 PD) ( Fig. 28C). Mesoscutellum dull, imbricate, medially with dense punctures (IS = 1 PD), laterally with moderate punctures (IS = 1–2 PD). Metanotum dull, impunctate, imbricate. Metapostnotum striate-rugulose, medially striae not reaching posterior margin, laterally striae extend onto dorsolateral slope, sculpture shining but imbricate, posterior margin rounded ( Fig. 28D). Propodeum lateral face dull, imbricate and impunctate, posterior face dull, imbricate and impunctate, lateral carina incomplete and oblique carina weakly present ( Fig. 28D). 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, with minute moderately sparse punctures (IS = 2–3 PD). T2 shining with similar punctures to T1.

Structure. Face short (FL/HW ratio 0.71 (± 0.04 SD)). Eyes convergent below [UOD/LOD ratio 1.13 (± 0.04 SD)]. Median ocellus width/ocellocular distance ratio [MOW:OOD ratio 0.50 (± 0.4 SD)]. Clypeus extends ~50% below suborbital tangent, clypeus length/width ratio 0.48 (± 0.08 SD). Clypeus with apicolateral denticles. Gena narrower than eye. Mandible short, almost reaching opposing clypeal angle. Protibial spur with apical serrations longer than length to width of malus. Inner metatibial spur minutely denticulate with three small, rounded and separated teeth less than one third width of rachis. Distance between parapsidal line (at the starting point) 0.72 (± 0.04 SD) mm. Pronotal angle rounded and weakly projected. Mesoscutum length/width (widest point) ratio 0.73 (± 0.06 SD). Mesoscutum/mesoscutellum length ratio 2.75 (± 0.18 SD). Mesoscutellum/metanotum length ratio 1.71 (± 0.14 SD). Stigma small, 0.55 mm long, 0.17 mm wide (ratio ~3.24 (± 0.03 SD)), margin in marginal cell convex, marginal cell 0.82 mm long, 0.24 mm wide, free portion about 2X that subtended by submarginal cells (0.58 mm: 0.29 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 SW corner of Western Australia ( Fig. 16).

Flight period. This species has been collected between October and December ( Table 1).

Floral hosts. MRYTACEAE: Calytrix sp. ; PROTACEAE: Lambertia sp.