Complex Scenarios of Reticulation, Polyploidization, and Species Diversity within Annual Pansies of Subsect. ( Sect. , Violaceae) in Italy: Insights from High-Throughput Sequencing and Plastid DNA Variation.

sect. , the so-called pansy, is an allopolyploid morphologically well-defined lineage of ca. 110 perennial and annual species in the northern hemisphere, characterized by markedly complex genomic configurations. Five annual pansies occur in Italy, four of which are morphologically very similar and belong to the informal ' species complex': (2 = 34), (2 = 16), (2 = 16), and (2 = 26). Their field recognition is difficult and reflects a long-debated taxonomy often resulting in doubtful records in field inventories and across European herbaria. The current lack of comprehensive intra- and interspecific comparative studies and a relative scarcity of appropriate genetic markers coupled with unambiguous cytological descriptions are hindering clear taxa circumscription and phylogenetic inferences within this group. In this work, we tested DNA sequence variation of three highly variable plastid markers and High-Throughput Sequencing (HTS) of the nuclear ribosomal region in an attempt to decipher species identity within the species complex and to obtain an insight on their genome organization and evolution. Our results document the close relationships within this species group, a reliable molecular resolution for , and the common ancestry of and the poorly differentiated and . Evidence of an important inter-population geographical divergence was recorded in and , pointing at the existence of different eco-cytotypes within these entities. Overall diversity patterns and the occurrence of two to four differently diverging lineages are discussed in the light of the acknowledged taxonomy and genomic evolutive trajectories of sect. .