Reassessment of the taxonomic status of Cyperaceae on Rapa Iti, Austral Islands, French Polynesia, with a new combination, Morelotia involuta

We reassess the current taxonomic status and distribution of Cyperaceae on Rapa Iti, Austral Islands, French Polynesia. This includes the poorly known Machaerina involuta H.St John (Cyperaceae, tribe Schoeneae), 86 years after it was first collected. Detailed morphological examination revealed that M. involuta belongs in Morelotia Gaudich., and the new combination, Morelotia involuta (H.St John) J.J.Bruhl & R.L.Barrett, is made here. Nineteen species of Cyperaceae are reported for Rapa Iti (10% of the vascular flora). The high diversity of Cyperaceae invites further discussion of the biogeographic connections and environmental conditions of Rapa Iti and a summary is provided. Notes on additional Cyperaceae named from Rapa Iti (Carex rapaensis (H.St John) K.L.Wilson, Carex stokesii F.Br., C. stokesii var. aristata F.Br., Cyperus rapensis F.Br., Eleocharis caribaea var. stokesii F.Br., Gahnia stokesii F.Br. and Rhynchospora stokesii F.Br.) are presented and a presently unidentified Carex is noted.