DNA barcoding reveals widespread occurrence of Leptidea juvernica (Lepidoptera: Pieridae) in southern Finland

DNA barcoding was used to identify 54 specimens of butterfly genus Leptidea collectedfrom various parts of southern Finland in 2011-2013. Results reveal the presence of boththe widespread Leptidea sinapis and its cryptic congener L. juvernica from several locationsthroughout the southern Finland. Our sampling also reveals different habitat preferencesbetween these species in Finland: specimens collected from open, disturbed habitatswere mainly identified as L. juvernica, whereas specimens from forest habitats were allfound to represent L. sinapis. A morphometric analysis revealed that L. juvernica and L.sinapis hardly differ by their fore wing shape, although males and females seem to differfrom each other. Our attempts to DNA barcode selected museum specimens failed andwe were not able to verify historical presence of L. juvernica in Finland. The recentlyincreased observations of Leptidea butterflies in large numbers in unusually open habitatsacross the southern Finland together with our findings suggests ongoing rapid expansionof L. juvernica in Finland.