Dransfieldia (Arecaceae) -: A new palm genus from western New Guinea

The systematic placement of the little-known species Ptychosperma micranthum (Arecaceae/Palmae: Arecoideae: Areceae) from far western New Guinea has been repeatedly disputed, resulting in recombinations in both Heterospathe and Rhopaloblaste. However, comparative morphological and molecular phylogenetic studies provide strong evidence against the placement of the species within any of these three genera, or indeed in any other accepted genus. Thus, a new genus, Dransfieldia, is herein described and a new combination, Dransfieldia micrantha, is made. Morphological character analyses demonstrate that the combination of character states that defines Dransfieldia is highly distinctive, despite the fact that many of the states are homoplasious. Dransfieldia micrantha is a slender, unarmed palm possessing a well-defined crownshaft, strongly ridged leaflets with entire, acute apices, an infrafoliar inflorescence with a persistent prophyll that is split apically by the exertion of the peduncular bract, a peduncle that is longer than the rachis, bullet-shaped multistaminate male flower buds in which the filaments in the outer whorl are irregularly inflexed in bud, and fruit with apical stigmatic remains. Molecular phylogenies strongly support the position of Dransfieldia within tribe Areceae, placing it within a clade of genera from the western Pacific.