Halictus cognatus Smith, F. 1853. Catalogue of Hymenopterous Insects in the Collection of the British Museum. Part I. Andrenidae and Apidae. London : British Museum 197 pp. [59].
Type data: Holotype BMNH Hym.17.a.900 ?, TAS (as Van Diemens Land).
Halictus haematostoma Cockerell, T.D.A. 1914. Descriptions and records of bees. LIX. Annals and Magazine of Natural History 8 13: 504–522 [506].
Type data: Holotype USNM 58165 ?, Windsor, VIC.
Halictus inclinans Smith, F. 1879. Descriptions of New Species of Hymenoptera in the Collection of the British Museum. London : British Museum xxi 240 pp. [36].
Type data: Holotype BMNH Hym.17.a.908 ?, Champion Bay (Geraldton), WA.
Halictus subinclinans Cockerell, T.D.A. 1915. Descriptions and records of bees. LXVIII. Annals and Magazine of Natural History 8 16: 1–9 [8].
Type data: Holotype USNM 58175 ?, Launceston, TAS.
Diagnosis. Combination of wing, mesoscutal punctation and colour characters unique. Both sexes with head and propodeum black, mesoscutum and scutellum shades of green to blue. Female with frons reticulate, mesoscutum punctation moderately coarse, surface dull, dorsal surface of propodeum ruguloso-striolate, defined by weak posterolateral carinae, forewing with 1st m-cu entering third submarginal cell. Male with antennae short, AS4 shorter than AS2+3, S2 with raised, mesial process, process smooth sided, truncate, with at least 6 lateral spines, hair on S3-S5 forming inverted V shape, forewing with 2nd r-m weaker than 1st r-m.
Remarks. The floral foraging record of L. cognatum is the most diverse recorded for a species of this subgenus (visits to 35 flowering plant families representing 63 genera). Three male specimens from central New South Wales and southeastern Queensland display macrocephaly.
