Vadensea Jongkind & O. Lachenaud 2019, gen. nov.
Creators: name: Jongkind, Carel C. H.
name: Lachenaud, Olivier
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Icacinales
Icacinaceae
Vadensea

description: Vadensea Jongkind & O.Lachenaud, gen. nov. (Figs. 1, 2, 3, 4 & 5).   
 Diagnosis:— Vadensea resembles Desmostachys in its sessile bisexual flowers with a distinct calyx and corolla, articulate at base and arranged in spikes (sometimes in glomerules in V. oblongifolia), but differs by its symmetrical, not compressed pyrenes having a reticulate endocarp, its petals that are hairy inside, its capitate stigma, its disk either cupuliform or absent, its inflorescences with flowers arranged more or less distichously and without bracts (or a single bract at the lowest node), and its usually erect habit (sometimes climbing in V. vogelii). In contrast, Desmostachys s.str. has the pyrenes asymmetrical (with a slight lateral indentation near the apex) and compressed, with a bumpy endocarp, the petals glabrous inside, a linear stigma, a 5-lobulate disk, inflorescences with spirally arranged flowers and bracts present at most nodes, and a climbing habit.   
 Type species:— Sarcostigma vogelii Miers [= Vadensea vogelii (Miers) Jongkind & O.Lachenaud].   
 Shrubs or small trees, rarely lianas. Leaves alternate, petiolate, margin entire; nervation pinnate, tertiary veins reticulate, acarodomatia absent. Inflorescences axillary to markedly supra-axillary, spicate or sometimes reduced and glomeruliform (rarely shortly branched in D. oblongifolius), ebracteate or sometimes with a single very short basal bract in D. oblongifolius. Flowers ± distichously arranged in rows and/or clusters, 4- or 5-merous, bisexual, sessile, articulate at base. Petals free or joined into a tube, glabrous or hairy outside, hairy inside. Stamens attached to the inside of the corolla, or free; filaments linear, much longer than the anthers, the latter not appendiculate. Style free, longer than the corolla; stigma capitate. Disk cupular or absent. Drupe ellipsoid, orange to red when mature. Pyrene ovoid or ellipsoid, symmetrical, not compressed; endocarp glabrous, prominently reticulate outside, smooth inside. Seed pendulous, with copious endosperm.   
 Etymology:— Vadensea is named after the “Herbarium Vadense” in Wageningen, The Netherlands, which for several decades (ca. 1955–2014) was one of the leading institutes in the taxonomy of African plants. During that relatively short period hundreds of new species were collected and described, and many generic monographs for Africa were published by its researchers (Breteler & Sosef 1996).   
 Distribution and ecology:— Vadensea includes four species in West and Central Africa, all of which occur in the Guineo-Congolian region (White 1979). The genus has a single endemic species in Upper Guinea (V. vogelii), three species in Lower Guinea of which two (V. tenuifolia, V. testui) are endemic to that region, and a single species in Congolia, which is shared with Lower Guinea (V. oblongifolia). All species of Vadensea occur in the undergrowth of evergreen or more rarely semi-deciduous rainforests, usually at low densities. No information is available on pollination or seed dispersal.
description: Published as part of Jongkind, Carel C. H. & Lachenaud, Olivier, 2019, Vadensea (Icacinaceae), a new genus to accommodate continental African species of Desmostachys, pp. 237-247 in Phytotaxa 405 (5) on pages 238-240, DOI: 10.11646/phytotaxa.405.5.2, http://zenodo.org/record/13715749