The ecological conditions at the first described European habitat of C. hylas (Zwingsee, Bavaria, GFR) correspond to those prevailing at a newly discovered locality, a subalpine lake in the Northern Alps (approx, alt. 1000 m). The author prefers not to publish the exact topographic position of the new locality, for fear the species may become extinct because of intense collecting as has been the case at Zwingseel. It is suggested that C. hylas extended its range into Central Europe only in the course of the last few decades, and that new records may be expected from other subalpine lakes, particularly also from the Carpathians.