Neither Phoebe nor Cinnamomum – the tetrasporangiate species of Aiouea (Lauraceae)

Cinnamomum is among the largest genera of the Lauraceae, including species from tropical to temperate Asia and from tropical to subtropical America. However, previous studies indicated that Cinnamomum might not be monophyletic in its current circumscription. We therefore re-investigated the genus and possible relatives with an increased taxon sample, particularly of the Neotropical species. Our results, based on sequences of the nuclear ITS region and the chloroplast spacers psbA-trnH and trnG-trnS, show that the Neotropical Cinnamomum species indeed do not form a monophyletic group with the Paleotropical species. Instead, the American species form a clade in which most species of the Neotropical genus Aiouea are nested within several subclades. According to the ITS data the Aiouea/Cinnamomum clade is sister to the likewise predominantly Neotropical Ocotea complex, rather than the two Paleotropical Cinnamomum clades. Therefore, Cinnamomum cannot be upheld in its current circumscription. As the type C. verum, is from Asia, the Neotropical species need to be placed in a different genus. We decided to transfer them to Aiouea here, because this is the oldest generic name in the Aiouea/Cinnamomum clade, and the only character separating Aiouea from Neotropical Cinnamomum is the number of pollen sacs per anther (di- vs. tetrasporangiate),
a feature that is known to be variable within several other genera as well. This transfer requires 42 new combinations and two nomina nova. In addition, six species described in the unpublished Ph.D. thesis of one of the authors (FLH) are validated in Aiouea here, and the only species of the genus Mocinnodaphne is transferred to Aiouea as well.