Another piece of the puzzle, another brick in the wall: The inevitable fate of Campanula section Quinqueloculares (Campanulaceae: Campanuloideae)

Campanula sect. Quinqueloculares (Campanulaceae), consisting of ca. 39 mostly chasmophytic species, is one of the most morphologically variable groups in Campanula and includes numerous endemics occurring mostly in Greece and/or Turkey. In this molecular study, we aim to test the monophyly of C. sect. Quinqueloculares and provide divergence time estimates to generate hypotheses into the historical processes responsible for the diversification and current distribution patterns of this group. Individual and combined data matrices consisting of plastid (NADHS-2, rpoC1-1, rpoC2-1, rpoC2-2, rpoC2-3, trnT-trnL) and nuclear (2017561, ITS, PPR11, PPR70) markers were constructed for 121 taxa. Results indicate that C. sect. Quinqueloculares, as traditionally circumscribed, is polyphyletic. Species are largely clustered into two well-supported clades, except for three taxa excluded from these groups. Additionally, a few taxa belonging to other sections are confidently nested within the two Quinqueloculares clades. The first clade (Greek clade) includes one isophylloid species nested with 25 Greek endemics belonging to C. sect. Quinqueloculares. The second clade (Southeastern Aegean-Turkish clade) comprises 20 C. sect. Quinqueloculares taxa and 3 species of C. sect. Rupestres, all distributed in the southeastern Aegean and Turkey. Divergence time estimates suggest that these clades originated in the Late Miocene. Temporal and geographic patterns are consistent with a vicariant scenario driven by geological events during the Miocene, such as the formation of the Mid-Aegean trench and the Messinian salinity crisis.