Phylogeny of the Herbaceous Tribe Spermacoceae (Rubiaceae) Based on Plastid DNA Data¹

Abstract

In its current circumscription, the herbaceous tribe Spermacoceae s.l. (Rubiaceae, Rubioideae) unites the former tribes Spermacoceae s. str., Manettieae, and the Hedyotis-Oldenlandia group. Within Spermacoceae, and particularly within the Hedyotis-Oldenlandia group, the generic delimitations are problematic. Up until now, molecular studies have focused on specific taxonomic problems within the tribe. This study is the first to address phylogenetic relationships within Spermacoceae from a tribal perspective. Sequences of three plastid markers (atpB-rbcL, rps16, and trnL-trnF) were analyzed separately as well as combined using parsimony and Bayesian approaches. Our results support the expanded tribe Spermacoceae as monophyletic. The former tribe Spermacoceae s. str. forms a monophyletic clade nested within the Hedyotis-Oldenlandia group. Several genera formerly recognized within the Hedyotis-Oldenlandia group are supported as monophyletic (Amphiasma Bremek., Arcytophyllum Willd. ex Schult. & Schult. f., Dentella J. R. Forst. & G. Forst., Kadua Cham. & Schltdl., and Phylohydrax Puff), while others appear to be paraphyletic (e.g., Agathisanthemum Klotzsch), biphyletic (Kohautia Cham. & Schltdl.), or polyphyletic (Hedyotis L. and Oldenlandia L. sensu Bremekamp). Morphological investigations of the taxa are ongoing in order to find support for the many new clades and relationships detected. This study provides a phylogenetic hypothesis with broad sampling across the major lineages of Spermacoceae that can be used to guide future species-level and generic studies.

Kadua haupuensis (Rubiaceae: Spermacoceae), a new endemic species from Kaua’i, Hawaiian Islands

“…& Schltdl., the earliest available generic name for these species (Terrell et al 2005). This position is substantiated by preliminary molecular evidence from ITS sequences (Kårehed et al 2008;Groeninckx et al, 2009).…”

“…& Schltdl., K. elatior (H. Mann) A. Heller, and K. flynnii (Kårehed et al, 2008;Groeninckx et al, 2009;Motley, unpubl.). This confirms morphological evidence suggesting this new species is most closely related to K. flynnii.…”

Description of 11 new Astiella (Spermacoceae, Rubiaceae) species endemic to Madagascar

“…5H, Q). This character combination is very rare within the Hedyotis-Oldenlandia complex in which species generally have multi-ovulate locules, tricolporate pollen and seeds without a ventral groove (Groeninckx et al 2009). Moreover, the two species have relatively large leaves, terminal inflorescences, flowers with a well-developed corolla tube, and broadly depressed obovoid capsules (Figs 8, 16).…”

Carajasia (Rubiaceae), a new and endangered genus from Carajás mountain range, Pará, Brazil

“…Andersson & Rova (1999) redefined and narrowed this concept by recognizing Knoxieae (including Triainolepideae and the 'Pentas group' of the tribe Hedyotideae) as a separate tribe. The proposal of Andersson & Rova (1999), often referred to as Spermacoceae s.l., was followed with minor modifications by other Rubiaceae specialists (Dessein 2003;Robbrecht & Manen 2006;Groeninckx et al 2009), and is also accepted in this paper. Robbrecht & Manen (2006) included 33 genera in Spermacoceae s.l., to which Groeninckx et al (2009) added other taxa; the tribe now comprises 61 genera with an estimated 1235 species.…”

“…The proposal of Andersson & Rova (1999), often referred to as Spermacoceae s.l., was followed with minor modifications by other Rubiaceae specialists (Dessein 2003;Robbrecht & Manen 2006;Groeninckx et al 2009), and is also accepted in this paper. Robbrecht & Manen (2006) included 33 genera in Spermacoceae s.l., to which Groeninckx et al (2009) added other taxa; the tribe now comprises 61 genera with an estimated 1235 species. Several new genera were described in Spermacoceae s.l.…”