Separation of Helophorus grandis, maritimus and occidentalis sp.n. (Coleoptera, Hydrophilidae) by banded chromosome analysis

Examination of the chromosomes shows that Helophorus grandis Ill. is a species quite separate from H.maritimus Rey. Further investigation shows that while the karyotype of H.grandis is the same in populations from southern England, northern and central France, and the northern half of Spain, that of H.maritimus from the Camargue is sufficiently different from supposed maritimus from central Spain for the Spanish specimens to be regarded as a separate species, here described as H.occidentalis sp.n. Aedeagophores of the three species are figured, along with additional maritimus ‐like material. No aedeagal or other morphological features for distinguishing maritimus and Occidentalis have been discovered. The implications of the discovery of two species of an H.maritimus complex are discussed.