Do molecules bear the key to solving a complex taxonomic problem? The Western Palearctic jewel leaf beetles in the genus Cryptocephalus Müller (Coleoptera, Chrysomelidae)

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The use of molecules to address taxonomic questions (e.g., DNA taxonomy, DNA barcoding) is perceived nowadays as the most promising approach to answer the question of how many species there are on the planet. The strategy is presented as alternative to traditional morphology-based taxonomy driven by specialists and intends to overcome some of the limitations of the latter approach. However, such a reductionist DNA-based methodology poses other equally worrying problems which become more apparent when dealing with groups of organisms which have speciated recently and/or have not developed strong isolation mechanisms, as species complexes. Incomplete lineage sorting of genetic variants or gene-flow mediated introgression can lead to erroneous biodiversity assessment. The European Cryptocephalus sericeus (Coleoptera, Chrysomelidae) is a species complex amenable to study the congruence of answers about species diversity using these alternative approaches. There is a solid framework for species hypotheses based on the analysis of adult morphology and male genitalia, proposing 20 taxa. However, there is also evidence pointing towards incomplete isolation of lineages with intermediate forms in geographical areas of overlap of two or more taxa (e.g., the Alps). In this proposal we plan to study the C. sericeus complex and a subordinated complex, the C. hypochaeridis complex, using phylogenetic and phylogeographic methods, respectively (the latter as a pilot study). In both cases, two independent genetic markers (mtDNA cytochrome oxidase 1 and nuclear rRNA internal transcribed spacer 2) will be used and, based on previous studies on similar organisms, we expect incongruence among them and with morphology, each taxonomic marker showing different geographical patterns. These results will be used to provide information about both the patterns of diversification in these species complexes and the underlying processes leading to the current species diversity in the group. They will also be used to caution about the use of single marker approaches for taxonomic inference (DNA barcoding).