The adults of both sexes, pupa and fourth instar larva of Culex (Culex) pajoti, a new species, are described and illustrated. The diagnoses of the female, male, larva and pupa of the new taxon are given, as well as its known distribution. Lastly, the systematics of Cx. pajoti, a new species, are discussed, its affinity to Cx. ingrami Edwards and related species being examined.