Chemistry, taxonomy and ecology of the potentially chimpanzee-dispersed sp.nov. (Rutaceae) endangered in coastal thicket in the Congo Republic.

Continuing a survey of the chemistry of species of the largely continental African genus , we investigate a species previously referred to as sp. 1 of Congo. From the leaves of sp. 1 we report six compounds. The compounds were three furoquinoline alkaloids, kokusaginine (1), maculine (2), and flindersiamine (3), two acridone alkaloids, arborinine (4) and 1-hydroxy-3-methoxy-10-methylacridone (5), and the triterpenoid, ß-amyrin (6). Compounds 1-4 are commonly isolated from other species, compound has been reported before once, from Malagasy , while this is the first report of ß-amyrin from . This combination of compounds has never before been reported from any species of . We test the hypothesis that sp. 1 is new to science and formally describe it as , unique in the genus in that the trifoliolate leaves are subsessile, with the median petiolule far exceeding the petiole in length. Similar fleshy-leathery four-locular syncarpous fruits are otherwise only known in the genus in (formerly the monotypic genus Engl.), a potential sister species, but requiring further investigation to confirm this phylogenetic position. We briefly characterise the unusual and poorly documented Atlantic coast equatorial ecosystem, where is restricted to evergreen thicket on white sand, unusual in a genus usually confined to evergreen forest. This endemic-rich ecosystem with a unique amphibian as well as plants, extends along the coastline from the mouth of the Congo River to southern Rio Muni, a distance of about 1,000 km, traversing five countries. We map and illustrate and assess its extinction risk as Endangered (EN B1ab(iii)+B2ab(iii)) using the IUCN, 2012 standard. Only three locations are known, and threats include port and oil refinery construction and associated activities, with only one protected location, the Jane Goodall Institute's Tchimpounga Reserve. Initial evidence indicates that the seeds of are dispersed by chimpanzees, previously unreported in the genus.