Plateumaris sericea
Copyright Malcolm Greenwood.

Note: P. discolor may be a synonym of P. sericea, since P. sericea with smooth pronota intergrade with P. discolor with wrinkled pronota. For a discussion, see J. Bratton & M. Greenwood 1997. British reed beetles, Plateumaris and Donacia (Chrysomelidae): an identification aid using pronotum surface characters. Latissimus 11-14.