Phylogeny, species delimitation and revision of Pleioluma (Sapotaceae) in New Caledonia, a frequently gynodioecious genus

Pleioluma (Baill.) Baehni (Sapotaceae) circumscribes some 40 medium-sized trees and shrubs, many gynodioecious, in Australia, Malesia and New Caledonia. Systematics of the group is unclear and delimitations of species are notoriously difficult. We explore species boundaries in New Caledonia by multiple accessions of 'species', molecules and morphology in a Bayesian framework. The molecular phylogenetic signal is weak, but morphology provides enough information to support groups, species and recognition of one cryptic species. Pleioluma is then revised for New Caledonia, a genus distinguished by areolate higher leaf venation, sepals being pubescent on both surfaces, stamens inserted in or below the middle of the corolla tube, presence of staminodes, foliaceous cotyledons and endosperm. Seventeen endemic species are recognised with descriptions, recognition notes, distributions, etymologies and conservation assessments. Six species are described as new, of which four are assigned IUCN preliminary status as Critically Endangered and in urgent need of protection (Pleioluma acutifolia Swenson & Munzinger, P. belepensis Swenson & Munzinger, P. butinii Swenson & Munzinger and P. tchingouensis Swenson & Munzinger). The new species, P. dioica Swenson & Munzinger and P. tenuipedicellata Swenson & Munzinger are respectively assessed as Data Deficient and Vulnerable. The micro-endemic species P. vieillardii (Baill.) Swenson & Munzinger, confined to the Koniambo massif, is also critically endangered and needs urgent conservation management