We report the discovery of Aedesnigrinus (Eckstein, 1918) in the New Forest of southern England, bringing to 36 the number of mosquito species recorded in Britain. Because it seems that this species has been misidentified previously in Britain as the morphologically similar Aedessticticus (Meigen, 1838), the two species are contrasted and distinguished based on distinctive differences exhibited in the adult and larval stages. The pupa of Ae.nigrinus is unknown, but the pupa of Ae.sticticus is distinguished from the pupae of other species of Aedes by modification of the most recent key to British mosquitoes. The history of the mosquito fauna recorded in the UK is summarized and bionomical information is provided for the two species.