Choosy vegetarians: Longitarsus substriatus Kutschera and L. tristis Weise (Coleoptera Chrysomelidae), two flea beetles new to Northern Europe

The beetle fauna of the Baltic islands Oeland and Gotland, hosts a number of species with a mainly southeastern distribution in Europe. Apart from these outlying localities, their distribution usually reaches no further north than the northern parts of the Danube river basin in Slovakia. Examples of such species are the pollen beetle Meligethes hoffmanni Rtt. and the leaf beetles Galeruca jucunda (Faldermann) (G. circumdata Duft.), Cryptocephalus elongatus Germ, and Longitarsus medvedevi Shapiro. Ecologically, all are restricted to areas with a xerothermic environment, which also occurs on the limestone pavement of the Baltic islands. The number of such species is now increased by the discovery of two species of flea beetles. Longitarsus substriatus Kutschera is closely related to L. lycopi (Foudras) but feeds exclusively on Water Germander, Teucrium scordium L.. It is now recorded from both Oeland and Gotland, where the host plant also occurs outside its normal range. In the east, the distribution of L. substriatus reaches north to Slovakia and southern Poland and in the west there are northern outlying localities in the Paris area. Our investigation also demonstrated that L. lycopi, which was reported from several provinces in Sweden, is also restricted to the Baltic Islands. The second species is Longitarsus tristis Weise, which was discovered among unidentified Longitarsus material from Gotland. This species is monophagous on Spear-leaved Scullcap, Scutellaria hastifolia L., which is distributed along the Baltic coast in Sweden but quite rare and considered threatened in central Europe. L. tristis is likewise a south-eastern species, but has an isolated colony in the Elbe river-valley in Germany.