Melectini

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Ecdysozoa
Cladus: Panarthropoda
Phylum: Arthropoda
Subphylum: Hexapoda
Classis: Insecta
Cladus: Dicondylia
Subclassis: Pterygota
Cladus: Metapterygota
Infraclassis: Neoptera
Cladus: Eumetabola
Cladus: Endopterygota
Superordo: Hymenopterida
Ordo: Hymenoptera
Subordo: Apocrita
Superfamilia: Apoidea

Familia: Apidae
Subfamilia: Apinae
Tribus: Melectini
Genera: Afromelecta – Brachymelecta – Melecta – Sinomelecta – Tetralonioidella – Thyreomelecta – Thyreus – Xeromelecta – Zacosmia
Name

Melectini Westwood, 1839
References

Westwood, J.O. 1839: An introduction to the modern classification of insects. Longman, Orme, Brown, Green, and Longmans, London.
Linsley, E.G.. 1939. A revision of the nearctic Melectinae. Annals of the Entomological Society of America 32: 429-468.

The Melectini are a tribe of medium- to large-sized apid bees found essentially worldwide. They are brood parasites of the related typical digger bees (Anthophorini) and occasionally visit flowers e.g. in prairie landscapes of the United States.[1]

As in other cuckoo bees, females can be easily distinguished from those of their hosts by the lack of scopae and other pollen-collecting adaptations, as well as lacking prepygidial fimbria and basitibial plates. Their body hair is rather short and on the abdomen lies flat against the exoskeleton. They may, therefore, be difficult at first glance to distinguish from the Nomadinae, but the details of their wing venation are characteristic: the marginal cell is shorter than the first two submarginal cells, and the second abscissa of vein M+Cu is extremely short, with the cells it connects being almost adjacent to each other. The jugal lobes are very small, less than half as long as the vannal lobes.[1]
Genera

These bee genera belong to the Melectini:[2]

Afromelecta Lieftinck 1972
Brachymelecta Linsley 1939
Melecta Latreille 1802 (= Bombomelecta, Symmorpha)
Sinomelecta Baker 1997
Tetralonioidella Strand 1914 (= Callomelecta, Protomelissa)
Thyreomelecta Rightmyer & Engel 2003
Thyreus Panzer 1806 (= Crocissa, Crocisa)
Xeromelecta Linsley 1939
Zacosmia Ashmead 1898 (= Micromelecta)

Several of these (Afromelecta, Melecta, and Xeromelecta) have subgenera which some authors may consider independent genera.[2]
References

Stephen, W.P.; Bohart, G.E. & Torchio, P.F. (1969): The Biology and External Morphology of Bees, With a Synopsis of the Genera of Northwestern America. Oregon State University Press, Corvallis, Oregon. PDF fulltext[permanent dead link]
Yanega, Doug (2007): Bee Genera of the World. Version of 2007-SEP-31. Retrieved 2008-MAY-06.