Two new species of Thiollierea Montrouz. (Rubiaceae, Chiococceae) endemic to New Caledonia are described and illustrated. Both belong to the group of species with large red and/or yellow flowers. Each one is micro-endemic of one to two ultramafic massifs in the northwestern coast of Grande Terre. Thiollierea papineaui Barrabé & Fleurot, sp. nov. ressembles T. lenormandii (N.Hallé & Jérémie) Barrabé & Mouly but differs in having compact uniflorous inflorescences with a shorter peduncle, and larger calyx lobes. Thiollierea naounarum Fleurot & Barrabé, sp. nov. is morphologically close to T. macrophylla (Brongn.) Baum-Bod. but it differs in having usually uniflorous inflorescences, foliaceous bracts, zygomorphic flowers, and warts on hypanthium. Additionally T. papineaui, sp. nov. is micro-endemic to the Tiébaghi massif and to the base of Mount Kaala, in the area of Karembé. Thiollierea naounarum Fleurot & Barrabé, sp. nov. has only been observed and collected to the base of the Kopéto massif. Thiollierea papineaui, sp. nov. is assessed as “Endangered” and T. naounarum Fleurot & Barrabé, sp. nov. as “Critically Endangered” using the IUCN Red List Categories and Criteria.
Chiococceae, New Caledonia, identification key, endemism, IUCN Red List, ultramafic substrate