Taxonomic revision of Pycnandra subgenus Trouettia (Sapotaceae), with six new species from New Caledonia

摘要

Pycnandra (Sapotaceae, Chrysophylloideae) is endemic to New Caledonia, with ~60 species, and is subdivided into five (or six) subgenera. Here, we revise P. subg. Trouettia and recognise 17 species of which six (P. bourailensis, P. caeruleilatex, P. confusa, P. elliptica, P. pubiflora and P. sessiliflora) are described as new and provide 10 new combinations. The subgenus is found only in Grande Terre, the main island of New Caledonia. The members occur in a wide range of habitats, from dry maquis vegetation to moist humid forest, from sea level to the higher massif, and all species except P. bourailensis and P. sarlinii are restricted to ultramafic soils. Pycnandra is characterised by the absence of staminodes, a single-seeded fruit, plano-convex cotyledons and the absence of endosperm. Pycnandra subg. Trouettia is distinguished on a character combination of several homoplastic features such as alternate and tomentulose leaves, pubescent ovary and a broad seed scar. The corolla is tomentulose on the outer surface of six species, a character shared with one species in P. subg. Achradotypus. Because of past and present mining activities in New Caledonia and because these species are restricted to habitats on ultramafic soils, conservation assessments are urgently needed. Preliminary IUCN Red List assessments are provided for all members of subg. Trouettia. Six taxa (P. deplanchei subsp. deplanchei, P. deplanchei subsp. floribunda, P. intermedia, P. obscurinerva, P. sarlinii, P. sessiliflora) are proposed the IUCN status of Vulnerable; P. caeruleilatex, P. elliptica and P. schmidii are considered to be Endangered, and the two species P. bourailensis and P. confusa are proposed to be listed as Critically Endangered.