Molecular Phylogeny of Typhonium sensu lato and Its Allied Genera in the Tribe Areae of the Subfamily Aroideae (Araceae) Based on Sequences of Six Chloroplast Regions

Typhonium was recognized as a monophyletic genus in the tribe Areae of the subfamily Aroideae (Araceae) until a recent molecular phylogenetic study indicated that the genus was paraphyletic respective to other Areae genera. However, that phylogenetic study did not discuss the details of infrageneric relationships due to the limited numbers of Typhonium samples. To elucidate the phylogenetic relationships in Typhonium sensu lato, we conducted phylogenetic analyses based on the combined DNA sequences of six chloroplast regions (3′trnL–trnF, rpl20–5′rps12, psbB–psbH, trnG intron, rpoC2–rps2, and trnK 3′intron) from 18 representative Typhonium species and additional samples from related genera. The resultant tree strongly suggests that Typhonium is not a monophyletic group and that it comprises at least two separate lineages, with other Areae genera nested within, and that Typhonium sensu lato may be subdivided into several monophyletic groups. These groups are distinguishable based on the stem-type of shoot organization as well as other morphological characters, which mostly correspond to traditionally recognized taxa. Based on molecular phylogeny and morphology, we proposed a revision of the Areae, wherein Typhonium sensu lato is divided into four genera: Typhonium sensu stricto, Sauromatum, and three new genera, Diversiarum , Hirsutiarum , and Pedatyphonium , which are described here which results in the following combinations: Diversiarum diversifolium , Diversiarum alpinum , Pedatyphonium horsfieldii, Pedatyphonium larsenii , Pedatyphonium kunmingense , Pedatyphonium calcicolum , Pedatyphonium omeiense , Hirsutiarum hirsutum , Hirsutiarum brevipilosum , and Sauromatum giganteum .