Molecular and morphological phylogenetic reconstruction reveals a new generic delimitation of Asian Derris (Fabaceae): Reinstatement of Solori and synonymisation of Paraderris with Derris

Abstract

The genus Derris is a problematic taxon within tribe Millettieae, because of the various generic circumscriptions proposed by different authors. Previous molecular phylogenetic studies proved Derris s.l. to be polyphyletic and thus unacceptable as a taxon. Moreover, the most recent circumscription of Derris s.str. was also not monophyletic. In this study, 29 qualitative morphological characters were analyzed together with the molecular data of our earlier studies. The combined datasets confirmed the monophyly of Solori (also known as Brachypterum) and showed it to be distinct at the generic level with the following synapomorphies: presence of stipellae, more than five flowers per brachyblast, tubular and (or) lobed floral disk, seven to twelve ovules and one-winged pods with obvious seed chambers when dry. Paraderris appeared to be a wellsupported monophyletic group, but nested within Derris s.str. In order to maintain the monophyly of Derris s.str., Paraderris is synonymised with Derris s.str., which broadens the generic circumscription for Derris s.str. This Derris s.str. only has two synapomorphies, the liana habit and two-winged pods. Other morphological characters used for previous generic circumscriptions of Derris s.str. appeared to be based on combinations of plesiomorphies. No infrageneric classification of Derris s.str. will be provided, because of low support for clades and lack of obvious apomorphies for several clades. Taxonomic treatment and nomenclatural changes are presented where necessary. © International Association for Plant Taxonomy (IAPT) 2014.