Relict populations of Lyonetia ledi Wocke, 1859 (Lepidoptera, Lyonetiidae) from the Alps indicate postglacial host-plant shift to the famous Alpenrose (Rhododendron ferrugineum L.)

Lyonetia ledi Wocke, 1859 (Lyonetiidae), was hitherto considered as a boreal species with a circumpolar distribution pattern and relict populations in isolated peat bogs north-east of the Alps (Austria, Czech Republic, Germany). In Europe it is known as a leaf-miner on Rhododendron tomentosum Stokes ex Harmaja (Ericaceae) as the primary host-plant and also Myrica gale L. (Myricaceae). The first record of L. ledi from the Swiss Alps on Rhododendron ferrugineum L., the famous Alpenrose, indicates an ancient host-plant switch during postglacial periods when R. tomentosum and R. ferrugineum shared habitat in the prealps. Conspecificity with northern populations is supported by the adult morphology and supplementing DNA barcodes (mtDNA COI gene). L. ledi is the first obligatory leaf-mining species on R. ferrugineum. Details of the life-history and habitat are described and figured. The record finally substantiates the probability of an autochthonous population in Carinthia (Austria), from where the species was recently published as new to the Alps.