The Pleuranthodium (Zingiberaceae) of Mount Wilhelm, Papua New Guinea

Three species of Pleuranthodium were encountered and collected during a survey of gingers at Mount Wilhelm, Chimbu Province, Papua New Guinea. Based on new material, the only previously known Pleuranthodium from this area, P. piundaundense, is described in more detail highlighting new diagnostic characters and its known distribution range is expanded based on identification of older specimens at Edinburgh from two other provinces. Two species so far only known from Mount Wilhelm could not be identified after studying all protologues, types and material from several herbaria. These are here described as new species, P. corniculatum and P. sagittatum. A key with both floral and vegetative characters is provided to all three species. Pleuranthodium corniculatum is distinct in having apical appendages on the calyx, and P. sagittatum has a wrinkled calyx. All species are described and illustrated, and conservation assessments are made.