A redefinition and taxonomic revision is given of the genus Lydda. Twenty-one species are attributed to this genus occurring in New Guinea and northern Australia. The zoraidine genera with short antennae are keyed and all Lydda species are keyed and redescribed with emphasis on the male and female genitalia. Four species are described as new: Lydda perlucida, L. guttata, L. cornuta and L. fusca; 16 species are transferred from Proutista to Lydda given 16 new combinations. P. awarensis Van Stalle, 1986 is synonymized with L. gemina Muir, 1913. Arfaka Distant, 1907 and Afakia Kirkaldy, 1909, former synonyms of Proutista are now considered as synonyms of Lydda. The Afrotropical species attributed to Lydda are transferred to Diostrombus, new subgenus Lyddastrombus, giving seven more new combinations. Proutista jezeki Dlabola, 1979 and P. jezeki Dlabola, 1981 are transferred to Diostrombus s. str., giving D. jezeki (Dlabola) comb. n. and D. adila (Dlabola) comb. n. A lectotype is selected for Lydda elongata, Lydda perkinsi, L. lutea, L. lurida, L. decisa, L. straminea, L. lumholtzi, L. australis, L. gemina, L. koebelei, L. calypso and Philadelpheia pandani. Diostrombus muiri nom. n. is proposed for D. cocos Muir, 1928, a secondary junior homonym of D. cocos (Muir, 1926) comb. n.