An update on the genus Monoon (Annonaceae) in the New Guinea region

Abstract

Five new species and one new record are reported for the genus Monoon in Papuasia while the limits of the M. polycarpum group are clarified. Confusion regarding the proper application of names between the similar species M. polycarpum (Burck) B.Xue & R.M.K.Saunders and M. oblongifolium (C.B.Rob.) B.Xue & R.M.K.Saunders has led to either name being used interchangeably in New Guinea, despite the latter being a Philippine endemic. To resolve the confusion among this group, all Papuan specimens formerly treated under these two names are recognized here as a single variable species, combined under M. chloroxanthum Miq., with a revised description. An easily recognizable and widespread new species, M. excelsum Ezedin, is described, segregated from a large subset of material that had been incorrectly treated under M. polycarpum for nearly a century. It is distinguished by its massive size, being an emergent canopy tree with larger leaves, higher secondary vein count, longer petals, fewer carpels and stamens, and fewer but larger monocarps. Four others, M. ascendens Ezedin, M. gisorum Ezedin, M. laxatum Ezedin, and M. prolixum Ezedin, are additionally described. Finally, M. barnesii (Merr.) B.Xue & R.M.K.Saunders, previously considered a Philippine endemic, is newly reported for New Guinea and Bougainville with an updated description while the distribution of M. pachypetalum I.M.Turner & Utteridge is expanded. Brief notes on the genus, including a discussion on species limits, along with a key to the nine Papuasian species, are provided.