Taxonomic revision of the Australian bee subgenus Ctenonomia, a reappraisal of the Australian subgenus Glossalictus and overviews of the Australian and New Zealand Lasioglossum subgenera (Hymenoptera: Apoidea: Halictidae: Lasioglossum).

Australian species of the Lasioglossum Curtis 1833 subgenus Ctenonomia Cameron 1903 are revised, to stabilise the taxonomy, and to facilitate identifications. This revision resolved there are 15 valid Australian species in this subgenus. Ten new species are erected, five described species are confirmed valid, six new synonyms are made and one described species has a new status. For Australian Lasioglossum (Ctenonomia) new species include: L. (C.) batleyinew species, L. (C.) boreumnew species, L. (C.) flutinumnew species, L. (C.) floccosumnew species, L. (C.) forresti (Cockerell 1906), L. (C.) hirtiglossanew species, L. (C.) leviorumnew species, L. (C.) luculentumnew species, L. (C.) picticorne (Cockerell 1930a), L. (C.) quadrifidumnew species, L. (C.) rotundatumnew species, and L. (C.) sagittanew species. New synonyms include: Halictus tribuarium Rayment 1935 is a new junior subjective synonym of L. (C.) clarigaster (Cockerell 1918); Halictus repertulus Cockerell 1916b, Halictus semipolitus expulsus Cockerell 1916c, Halictus speculellus Cockerell 1918 and Halictus barretti Cockerell 1929a are new junior subjective synonyms of L. (C.) semipolitum (Cockerell 1916b); and, Halictus cyclurus Cockerell 1915a is a new junior subjective synonym of L. (C.) sturti (Cockerell 1906). Lasioglossum (Ctenonomia) blandulum (Cockerell 1929c) is transferred to L. (Chilalictus) blandulumnew status. A case of secondary homonymy is addressed, which occurred when Homalictus was reclassified to a subgenus of Lasioglossum. Lasioglossum (Ctenonomia) punctatum (Smith 1858, Indonesia) is a senior primary homonym of L. (Homalictus) punctatum (Smith 1879, Australia). Lasioglossum (Homalictus) exlautum (Cockerell 1905, Australia), originally described as a subspecies of L. punctatum, is the valid name for the Australian species. All valid Ctenonomia species are described or redescribed, some with the male sex for the first time. Keys to both sexes, taxonomy, chresonymy, subgenus and species diagnoses, taxonomic notes, biology, etymologies, (re)descriptions, colour montage and SEM images, floral hosts, flight phenologies, range and distribution maps are provided. Analyses of species distributions, floral data, flight, phenologies discussions on associated organisms, female acarinaria, male sternal/tergal "mite pouch", female macrocephaly, and sternal hair types are presented and compared with other Australian Lasioglossum subgenera. The Australian endemic and monotypic Lasioglossum subgenus Glossalictus is reappraised and retained as valid. A review of subgeneric morphological characters suggests Glossalictus is most closely aligned with the subgenus Chilalictus. Both sexes are redescribed, figured and characters discussed. This study marks the completion of revisions for all Australian Lasioglossum subgenera. The Australian Lasioglossum fauna contains 264 valid species with 12 valid subgenera. These revisions have erected four new subgenera, 120 new species, synonymised 187 species and one subgenus and removed one subgenus from the Australian fauna. Biological and morphological overviews and keys to both sexes for the Australian and New Zealand Lasioglossum subgenera are presented.