Langat, M. | Search bioRxiv

bioRxiv2022

Chemotaxonomy supports morphology in the identification of Vepris hemp (Rutaceae) a new species of Critically Endangered deciduous forest shrub from Usambara Mts, Tanzania.

Hemp 7152, a sterile herbarium plot voucher of a shrub from a rare type of deciduous forest in the Usambara Mts, Tanzania was tentatively identified using morphology as a new species of Vepris (Rutaceae). To gain further support for its placement its chemistry was investigated. The compounds isolated from Hemp 7152 were four quinoline alkaloids, kokusaginine (1), N-methylplaty-desminium ion (9), ribalinium ion (10), and isoplatydesmine (11), and seven acridone alkaloids, arborinine (2) 1,2,3-trimethoxy-N-methylacridone (3), 1,2,3,5-tetramethoxy-N-methylacridone (4), 1,3-dimethoxy-N-methylacridone (5) and toddaliopsis A (6), evoxanthine (7) and tecleanthine (8). In addition, lupeol and ferulic acid were isolated from this plant. The combination of quinoline and acridone alkaloids is restricted to the Rutaceae family, confirming beyond reasonable doubt the placement of this material in the Rutaceae. Within Rutaceae in tropical Africa, only the genus Vepris is unarmed, with trifoliolate leaves. Using an identification key, and herbarium specimen matching, Hemp 7152 was morphologically placed as close to Vepris uguenensis, sharing xerophytic characters unusual in the genus. The species are geographically close, occurring in adjoining mountains in northern Tanzania. However, Vepris uguenensis contains 13 alkaloids which are not present in Hemp 7152, nor in any other species of Vepris that has been studied, supporting species recognition for Hemp 7152 which is formally named as Vepris hemp, morphologically characterised, illustrated and assessed as Critically Endangered using the IUCN 2012 standard. The new species appears restricted to an almost extinct type of deciduous forest, characterised in this paper.

plant biology↗

bioRxiv2021

Chemistry, Taxonomy and Ecology of the potentially chimpanzee-dispersed Vepris teva sp.nov. (Rutaceae) of coastal thicket in the Congo Republic

Continuing a survey of the chemistry of species of the largely continental African genus Vepris, we investigate a species previously referred to as Vepris sp. 1 of Congo. From the leaves of Vepris 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, {beta}-amyrin (6). Compounds 1-4 are commonly isolated from other Vepris species, compound 5 has been reported before once, from Malagasy Vepris pilosa, while this is the first report of {beta}-amyrin from Vepris. This combination of compounds has never before been reported from any species of Vepris. We test the hypothesis that Vepris sp.1 is new to science and formally describe it as Vepris teva, unique in the genus in that the trifoliolate leaves are subsessile, with the median petiolule far exceeding the petiole in length. Similar fleshy-leathery 4-locular syncarpous fruits are otherwise only known in the genus in Vepris glaberrima (formerly the monotypic genus Oriciopsis 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 Vepris teva is restricted to evergreen thicket on white sand, unusual in a genus usually confine 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 1000 km, traversing five countries. We map and illustrate Vepris teva and assess its extinction risk as Endangered (EN B1ab(iii)+B2ab(iii)) using the IUCN 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 Institutes Tchimpounga Reserve. Initial evidence indicates that the seeds of Vepris teva are dispersed by chimpanzees, previously unreported in the genus

plant biology↗