The rps16 intron and the phylogeny of the Rubioideae (Rubiaceae)

Abstract

The phylogeny of the subfamily Rubioideae (Rubiaceae) was estimated from sequence variation in the rps16 intron (cpDNA) in 143 ingroup and 5 outgroup taxa. The analysis largely confirms a recent one based on rbcL sequences, but branch support is often much stronger. Three of the traditional subfamilies are supported, Rubioideae, Cinchonoideae s. str., and Ixoroideae s. l. while there is no support for Antirheoideae. The Rubioideae are the sister group of all other Rubiaceae and comprise the tribes Anthospermeae, Coccocypseleae, Cruckshanksieae, Coussareeae, Gaertnereae, Hedyotideae, Knoxieae, Morindeae, Ophiorrhizeae, Paederieae, Pauridiantheae, Perameae, Psychotrieae, Rubieae, Spermacoceae, Theligoneae, and Urophylleae. The Hamelieae and Hillieae belong to the Cinchonoideae. Rachicallis and Siemensia should be transferred from the Hedyotideae to the Cinchonoideae. The Pauridiantheae, Urophylleae, Ophiorrhizeae, and Raritebe form the basalmost subclade of the Rubioideae. The second basalmost clade consists of the genera Lasianthus and Perama. The third basalmost clade consists of the tribes Coussareeae, Coccocypseleae and Cruckshanksieae, and the genera Declieuxia and Hindsia. The tribes Knoxieae, Anthospermeae, Argostemmateae, Paederieae, Theligoneae, Rubieae, Hedyotideae, and Spermacoceae are members of one clade. The Knoxieae are monophyletic if Otiophora, Otomeria, and Pentas are included. The tribe Anthospermeae is supported as monophyletic, but its subtribes are not. The Paederieae, together with Theligonum, form a paraphyletic grade basal to the Rubieae. The Hedyotideae, including Schismatoclada, form a grade at the base of the Spermacoceae. The Gaertnereae are monophyletic and distinct from the Psychotrieae. The Morindeae are monophyletic and include Damnacanthus and Mitchella. Schradera is the sister group of the Morindeae. The Psychotrieae are monophyletic when the Gaertnereae, Lasianthus, and Declieuxia are excluded. The recognition of a subtribe Hydnophytineae leaves the rest of the Psychotrieae paraphyletic. Psychotria is paraphyletic with respect to all other genera of the tribe. Approximately 50 genera are here classified for the first time based on molecular data.