Additional descriptions or notes of the adults and hitherto unknown pupae and larvae of Culex (Eumelanomyia) malayensis Sirivanakarn 1972, simplicicornis Edwards 1930 and selai Klein and Sirivanakarn 1969 from Peninsular Malaysia are presented. Culex jefferyi, a new species closely related to malayensis is recognized. Taxonomic discussions summarizing the diagnostic features and the records of distribution and bionomics of every species are given.