The phylogeny, evolution, and classification of the genus Globba and tribe Globbeae (Zingiberaceae): appendages do matter

The genus Globba (100 species) is one of the largest genera in the primarily tropical Zingiberaceae. Globba along with the small genera Gagnepainia, Hemiorchis, and Mantisia comprise the Globbeae, one of the two tribes of subfamily Zingiberoideae. Traditional infrageneric classification in Globba has focused on the number of anther appendages: zero, two, or four. Parsimony and Bayesian analyses were conducted on nuclear internal transcribed spacer (ITS) and plastid trnK-matK data from a broad sampling of Globba and related genera. Results show Mantisia to be monophyletic but nested within Globba, while Hemiorchis and Gagnepainia are monophyletic genera that are sister to each other. Anther appendage number and shape, along with inflorescence and fruit morphology, are the most important characters for understanding evolutionary relationships in Globba. A new infrageneric classification system for Globba, recognizing three subgenera and seven sections is presented. The four species of Mantisia are formally transferred into Globba but retained as a distinct section. Within Globba, a notable biogeographic boundary is seen at the Isthmus of Kra in southern Thailand.