The Melitidae redefined and a review of the genera and species from the southern Indo-Pacific and South Atlantic Oceans (Amphipoda, Senticaudata, Hadzioidea, Melitidae).

This paper divides the family Melitidae into three subfamilies based on mouthpart morphology: the Dulichiellinae subfam. nov., the Megamoerinae subfam. nov. and the Melitinae Bousfield, 1973 stat. nov. The generic composition of the family is discussed and amended. The marine and estuarine species of the Melitinae recorded from the southern Indo-Pacific and South Atlantic Oceans are reviewed. Based on the examination of type material or material from near the type locality, the following species are redescribed and re-illustrated: Barnardomelita matilda (J.L. Barnard, 1972a) from Australia, Josephosella awa (J.L. Barnard, 1972b) from New Zealand, J. plumulosa (Zeidler, 1989) from Australia, Melita corticis Appadoo & Myers, 2005 from Mauritius, M. gayi (Nicolet, 1849) from Chile, M. inaequistylis Dana, 1852 from New Zealand, M. kauerti J.L. Barnard, 1972a from Australia, M. nitidula Ruffo, 1958 from Madagascar, M. oba J.L. Barnard, 1972a from Australia, M. orgasmos K.H. Barnard, 1940 from South Africa, M. setimera Appadoo & Myers, 2005 from Mauritius, M. simplex Myers, 1985 from Fiji, M. tristanensis K.H. Barnard, 1965 from Tristan Da Cunha, M. zeylanica Stebbing, 1904 from Sri Lanka, now recorded from South Africa. The new species Melita ascensionasp. nov. from Ascension Island, is described and illustrated. A neotype is designated for Melita gayi. The following species are diagnosed: Melita alluaudi Ledoyer, 1982 from Madagascar, M. festiva (Chilton, 1885) from Australia, M. lagunae Oliveira, 1953 from Brazil, M. lowryi Springthorpe, 2023 from New Zealand, M. mangrovi Oliveira, 1953 from Brazil, M. myersi G.S. Karaman, 1987 from Fiji, M. ophiocola Lowry & Springthorpe, 2005 from Australia, M. petronioi Senna et al., 2012 from Brazil, and M. sampsonae Lowry & Springthorpe, 2009 from Australia. Additional distribution records are provided which greatly increase the known ranges of several species. Keys to the genera of Melitidae and marine and estuarine Melitine species recorded from southern Indo-Pacific and South Atlantic Oceans are provided.