Reduction of the Hawaiian genusPlatydesmainto Melicope section Pelea (Rutaceae) and notes on the monophyly of the section.

Platydesma , an endemic genus to the Hawaiian Islands containing four species, has long been considered of obscure origin. Recent molecular phylogenetic studies have unequivocally placedPlatydesmawithin the widespread genusMelicopeas sister to the rest of the Hawaiian species ofMelicope. This makes submergingPlatydesmaintoMelicopenecessary. We make the necessary new combinations:Melicope cornuta(Hillebr.) Appelhans, K.R. Wood & W.L. Wagner, M. cornuta var. decurrens (B.C.Stone) Appelhans, K.R. Wood & W.L. Wagner,M. remyi(Sherff) Appelhans, K.R. Wood & W.L. Wagner, andM. rostrata(Hillebr.) Appelhans, K.R. Wood & W.L. Wagner. An additional species that has been recognized withinPlatydesmashould now be recognized under its original nameM. spathulataA. Gray. All Hawaiian species belong to Melicope section Pelea. Our molecular phylogenetic studies also showed that in addition to merging Platydesma into section Pelea, five species described from New Caledonia need to be excluded from the section in order to achieve monophyly of section Pelea.