Octoknema belingensis Gosline & Malécot

Gosline, G. & Malécot, V. Kew Bull (2011) 66: 367. https://doi.org/10.1007/s12225-011-9293-9

Morphology Leaves

Leaves narrowly elliptic to obovate, 15 – 30 × 5 – 10 cm, apex rounded to acute, acumen rounded to absent, to 1 × 1 cm, base rounded, glossy dark green above, dull and paler green below, occasional obscure stellate hairs on upper and lower side of lamina; midrib sparsely pubescent; secondary veins 7 – 9 pairs, ascending at an angle of 30° from midrib, barely anastomosing 2 mm from margin, glabrous below; tertiary veins visible, straight

Morphology Leaves Petiole

Petiole 1 – 2.5 cm long rounded with a distinct apical pulvinus, densely pubescent

Morphology Reproductive morphology Inflorescences

Male inflorescence unknown Female inflorescence known from fruiting material only; peduncle 10 – 15 mm long; fruits in clumps of 2 – 4

Morphology Reproductive morphology Fruits

Fruit orange-red when ripe, globose, 2 × 1.8 – 2 cm, densely pubescent; epicarp smooth, mesocarp 2 – 2.5 mm thick, woody in secco, endocarp 0.5 mm thick with 9 internal laminae

Morphology General Habit

Seedling (Setten 665, seedling of Breteler & de Wilde 589) with dark-green glabrous stem, tapered hypocotyl, main taproot with small secondary radicels, epigeal germination, 2 foliaceous cotyledons, opposite, base rounded, apex pointed, with 2 secondary nerves, glabrous. Tree to 12 m tall, 7 cm in diam. at 1.5 m; young twigs light brown beneath densely matted hairs; indumentum densely floccose, hairs erect 0.3 × 0.3 mm, light brown, appearing dark brown because of density; semidendritic hairs present to 1 mm long

Distribution

Only known from the Belinga mountains of Gabon.

Ecology

Rocky bed of permanent creek in closed high forest. Humid locality in shade or half-shade; 850 m elevation.

Conservation

This species is known only from a single collection in an area planned for a massive Chinese open cast iron mining project. It is assessed as IUCN (2001) category CR (critically endangered) using criteria B2ab(iii); area of occupancy 4 km2.

Note

Similar to Octoknema kivuensis in its dense floccose indumentum, but differing in having elliptic to obovate leaves rather than narrowly elliptic to narrowly obovate; the leaf bases subcordate rather than peltate, the fruits c. 20 mm in diam. rather than c. 14 mm and remains of the corolla minimal rather than hemispherical to 3 mm high.

We have chosen to name this taxon in spite of the limited material available because of its critically endangered status, resulting from the threat to the collection location. The Belinga Mountains are a Pleistocene refuge with some 19 known narrow endemic species (Leal 2008). The entire area is threatened by a controversial iron mining project (Polgreen 2009).