A new threatened species of Coelospermum Blume (Rubiaceae, Morindeae), endemic to northern New Caledonia and clarification of the status ofC. fragrans (Montrouz.) Baill. ex Guillaumin

The genus Coelospermum Blume is a group of Rubiaceae species from Southeast Asia, Australia and Oceania that consists of eleven generally lianescent species. Within the Morindeae tribe, Coelospermum is distinguished by its flowers with clearly exserted stamens. In New Caledonia, only three species were so far known, to which a fourth is added here, which is easily distinguished by its syncarpous fruits and its corolla with throat and lobes on the inner side densely hairy. This new species, named C. nomac sp. nov., is endemic to New Caledonia and more particularly micro-endemic to the far North, on the Tiebaghi massif and at the North Point of the Island. The low number of collectionss available as well as the unsuccessful prospecting efforts of 2019 and 2020 on Tiebaghi shows that this vine remains relatively rare and must be the subject of a threat and conservation assessment. The category CR ``critically endangered'' is provisionally suggested. Among the three other species, a taxonomic study suggests the use of another name for C. monticola, C. fragrans here neotypified.