New historical records of Graphoderus bilineatus from Belgium

In 2015 I wrote an article in which I gave an account of all known records of Dytiscus latissimus Linnaeus, 1758 and Graphoderus bilineatus (Degeer, 1774) from Belgium (Scheers, 2015). D. latissimus was last collected in 1921 near Kalmthout and for G. bilineatus this was in 1948 near Herentals. Thinking I had seen all material in the museum collections and the more important private collections, I mentioned nevertheless the possibility that there could still be extra records in unknown private collections. However, I found, more or less by accident, one box of Dytiscidae in the collections of the Royal Belgian Institute of Natural Sciences that I seem to have overlooked back then. In this box there were different species of Dytiscidae caught by Emile Derenne, including several interesting species like Ilybius subaeneus Erichson, 1837, Rhantus bistriatus (Bergsträsser, 1778) and also two specimens of Graphoderus bilineatus. One of those two specimens was taken on 21.V.1938 at “Bergh”. In Belgium there are, however, at least three villages called “Bergh” at that time and for now I cannot be certain which of these three was intended. The second specimen was taken at Zoerle (province of Antwerpen) on 18.VI.1950. This is the first record of this species in Belgium post 1949. The locality is located in the valley of the river Grote Nete, a region from which also four other historical records of this species are known.