Re-circumscription of the mimosoid genus Entada including new combinations for all species of the phylogenetically nested Elephantorrhiza (Leguminosae, Caesalpinioideae, mimosoid clade)

Shawn A O'Donnell; Jens J Ringelberg; Gwilym P Lewis

doi:10.3897/phytokeys.205.76790

Re-circumscription of the mimosoid genus Entada including new combinations for all species of the phylogenetically nested Elephantorrhiza (Leguminosae, Caesalpinioideae, mimosoid clade)

PhytoKeys. 2022 Aug 22:205:99-145. doi: 10.3897/phytokeys.205.76790. eCollection 2022.

Authors

Shawn A O'Donnell¹, Jens J Ringelberg², Gwilym P Lewis³

Affiliations

¹ Department of Geography and Environmental Sciences, Northumbria University, Newcastle upon Tyne, NE1 8ST, UK Northumbria University Newcastle upon Tyne United Kingdom.
² Department of Systematic and Evolutionary Botany, University of Zurich, 8008 Zurich, Switzerland University of Zurich Zurich Switzerland.
³ Accelerated Taxonomy Department, Royal Botanic Gardens, Kew, Richmond, TW9 3AE, UK Royal Botanic Gardens Richmond United Kingdom.

Abstract

Recent phylogenomic analyses of 997 nuclear genes support the long-held view that the genus Entada is congeneric with Elephantorrhiza. Entada is resolved as monophyletic only if the genus Elephantorrhiza is subsumed within it. The two genera were distinguished solely by relatively minor differences in the mode of dehiscence of the fruits (a craspedium separating into one-seeded endocarp segments in Entada versus a craspedium with the whole fruit valve breaking away from the persistent replum in Elephantorrhiza) and the craspedial fruit type itself provides a shared synapomorphy for the re-circumscribed Entada. Here, we provide a synopsis of Entada, including 11 new combinations in total, for the eight species, one subspecies and one variety previously placed in Elephantorrhiza, as well as a new combination for a subspecies of Entadarheedei Spreng. not previously dealt with when Entadapursaetha DC. was placed in synonymy. These new combinations are: Entadaburkei (Benth.) S.A. O'Donnell & G.P. Lewis, comb. nov.; Entadaelephantina (Burch.) S.A. O'Donnell & G.P. Lewis, comb. nov.; Entadagoetzei (Harms) S.A. O'Donnell & G.P. Lewis, comb. nov.; Entadagoetzeisubsp.lata (Brenan & Brummitt) S.A. O'Donnell & G.P. Lewis, comb. nov.; Entadaobliqua (Burtt Davy) S.A. O'Donnell & G.P. Lewis, comb. nov.; Entadapraetermissa (J.H. Ross) S.A. O'Donnell & G.P. Lewis, comb. nov.; Entadarangei (Harms) S.A. O'Donnell & G.P. Lewis, comb. nov.; Entadarheedeisubsp.sinohimalensis (Grierson & D.G. Long) S.A. O'Donnell & G.P. Lewis, comb. nov.; Entadaschinziana (Dinter) S.A. O'Donnell & G.P. Lewis, comb. nov.; Entadawoodii (E. Phillips) S.A. O'Donnell & G.P. Lewis, comb. nov.; and Entadawoodiivar.pubescens (E. Phillips) S.A. O'Donnell & G.P. Lewis, comb. nov. We provide a revised circumscription of the genus Entada which now comprises 40 species distributed pantropically, with the greatest diversity of species in tropical Africa. We present a complete taxonomic synopsis, including a map showing the global distribution of the genus and photographs showing variation amongst species in habit, foliage, flowers and fruits. A short discussion about extrafloral nectaries, mainly observed in the Madagascan species, is presented.

Keywords: Fabaceae; extrafloral nectaries; generic delimitation; monophyly; nomenclature; taxonomy.

Shawn A. O’Donnell, Jens J. Ringelberg, Gwilym P. Lewis.