Overlapping measurements in the length of the genitalia of Leptidea sinapis/reali collected in Slovenia triggered an investigation of a possible natural hybridization between these two well known sibling species of butterflies. Random polymorphic DNA (RAPD) was used to generate species specific markers and sequences of the cytochrome oxidase subunit one gene for determination of the progeny. RAPD's clustering and mitochondrial DNA (mtDNA) phylogeny were congruent with the taxonomic placement of specimens of both species, but slightly incongruent with the results of the analysis of genital morphology. Two specimens with L. reali genitalia measurements, but genetically belonging to L. sinapis, had species specific RAPD markers of both species indicating probable hybrid origin. All the specimens with genitalia of intermediate length were also genetically assigned to L. sinapis indicating a possible one way introgression as predicted from their genitalia morphology. Leptidea sinapis was found predominantly in xerothermic habitats in Slovenia, whereas L. reali was more of a generalist except in the sub-Mediterranean region where it is limited to humid meadows.
Using a large sample of museum and newly collected specimens of the cryptic butterfly species Leptidea sinapis and L. reali, identified/confirmed based on genital characters, the patterns in their geographical distributions, historical changes in range and briefly also their habitat associations in Poland, were investigated. Leptidea sinapis occurs mainly in the lowland and upland parts of the country and is rarer than L. reali, which is widespread throughout Poland, including the mountains. In the first half of the 20th century, the range of L. sinapis included the whole of Poland, whereas currently it is confined to eastern and southern regions. Historical records of the distribution of L. reali are concentrated in southern and central Poland. Currently it is recorded from localities throughout Poland. Leptidea reali is recorded most frequently in meadows and shows no clear preference for a particular level of humidity, while L. sinapis is found mainly in woodland and xerothermic habitats. The two species are syntopic within the present range of L. sinapis, which is now a declining and local species, whereas L. reali is now common and widespread. and Konrad Sachanowicz, Agnieszka Wower, Jaroslaw Buszko.