A new report of phytomelanin in cypselae of Vernonieae: the case of the type species of Lychnophora Mart.

Phytomelanin is a mechanically hard, blackish, and inert substance rarely found in plants. In Asteraceae, this substance was historically associated with the Heliantheae alliance, but recent studies have observed it in unrelated groups as Heterocoma and Wunderlichia. During a taxonomic investigation, we found phytomelanin in cypselae of Lychnophora salicifolia an unusual feature in Vernonieae previously found only in Heterocoma. Furthermore, phytomelanin fills the intercellular spaces of the sclerenchymatic outer mesocarp in L. salicifolia. Our results doubt the (syn)apomorphy status in Heterocoma, suggest the phytomelanin may have not the same evolutionary significance in Lychnophorinae as in other tribes and proposes new perspectives for evolutionary studies in Asteraceae.