The interpretation of Linnaeus' name Sphex semiaurata Linnaeus, 1761 has been controversial. After type examinations, we conclude that it is identical with the common Cleptes pallipes Lepeletier, 1806 and thus re-establish the old synonymy: Cleptes semiauratus (Linnaeus, 1761) (=Cleptes pallipes Lepeletier, 1806, syn. reinst.). We have been unable to find an available name for the species with which it has been confused. In order to be able to designate a suitable type specimen, we prefer to describe it as a new species rather than suggest a replacement name: Cleptes striatipleuris Rosa, Forshage, Paukkunen & Soon sp. nov. (=Cleptes semiauratus sensu Lepeletier, 1806, nec Linnaeus, 1761; =C. splendens sensu Linsenmaier 1959, nec Fabricius, 1798).