Based on a well preserved female specimen from Bitterfeld amber, Monolepta rappsilberi sp. nov. is described and illustrated using X-ray micro-computed tomography (CT). It is the second reported member of Chrysomelidae from this fossil resin and the first described fossil Monolepta representative. The fossil species represents a lineage that is extinct in Recent Europe. A longitudinal carina on abdominal ventrite 5 of the female is a unique character for the subfamily Galerucinae.