An analysis of morphometric and bionomic data (as well as the genetic evidence discussed in a companion paper) clearly shows that Meligethes matronalis Audisio & Spornraft, 1990 and M. subaeneus Sturm, 1845 (members of the Meligethes coracinus complex: Coleoptera, Nitidulidae, Meligethinae), recently synonymised by Kirejtshuk (1997), are distinct species. The two species are also compared with the closely related M. coracinus Sturm, 1845. Meligethes matronalis is strictly associated with Hesperis matronalis L. (Brassicaceae) in early Summer, whereas the larvae of the frequently syntopic M. subaeneus develop on Cardamine spp. (Brassicaceae) in Spring; M. coracinus is a more polyphagous species, developing from early Spring to late Summer mostly on Brassica spp., Sinapis spp., Barbarea spp. and Sisymbrium spp. (Brassicaceae).