Monanthotaxis bicornis (Boutique) Verdc.

Hoekstra, P. H., Wieringa, J. J., Maas, P. J. M. & Chatrou, L. W., 2021, Revision of the African species of Monanthotaxis (Annonaceae), Blumea 66 (2), pp. 107-221 : 129-130

6. Monanthotaxis bicornis (Boutique) Verdc. — Map 5

Monanthotaxis bicornis ( Boutique) Verdc.(1971b) 31. — Popowia bicornis Boutique (1951b) 115. — Lectotype (designated here): J.L.P. Louis 8957 (lecto BR ( BR0000008805386 );isolecto BR0000008805379 , BR6102005255172 , K000913657 , P00362792 ), Democratic Republic of the Congo, Orientale, Yamboa, 25 km au N.W. de Yangambi, 21 Apr. 1938.

Liana, to 30 m long; young branches yellow-brown, densely covered with appressed, yellow-brown hairs 0.2–0.4 mm long, becoming glabrous; old branches blackish brown. Leaves: petiole 3–5 mm long, 0.6–1 mm diam, terete, indument as on branches; lamina narrowly oblong-elliptic, 6–12 by 1.9–3.5 cm, 2.6–3.7 times longer than wide, chartaceous, not punctate, medium green above, glaucous below, above sparsely covered with appressed, whitish hairs 0.5–0.8 mm long, primary vein above densely covered with long-persistent, yellowish hairs 0.2–0.4 mm long, below densely to sparsely covered with appressed, yellowish hairs 0.1–0.2 mm long, base cuneate, with thickened black margin, apex acuminate, acumen 5–15 mm long, secondary veins 11–14 per side, hardly visible, tertiary venation percurrent, slightly raised above and reticulate, hardly visible below. Inflorescences axillary or c. 1 mm above axils or terminal, composed of solitary flowers to 3-flowered fascicle-like rhipidia; sympodial rachis absent or up to 7 mm long, densely covered with appressed, yellowish hairs; flowering pedicels 15–60 mm long, 0.3–0.6 mm diam, densely to sparsely covered with appressed, yellowish hairs 0.1–0.2 mm long; lower bracts absent or broadly to narrowly ovate, 0.5–1.3 by c. 0.4 mm, indument as on sympodial rachis; upper bract in lower half of the pedicel, ovate, 0.4–0.7 by 0.3–0.5 mm, indument as on pedicel; flower buds globose. Flowers bisexual; sepals free, depressed ovate, 1–1.3 by 2.3–2.6 mm, apex acute, densely covered with appressed hairs; receptacle 2.3–3.3 mm diam, flat; petals yellow to white, 6, in two whorls, outer petals broadly ovate, 4–6.7 by 4.6–6 mm, outside densely covered with appressed, yellow-brown hairs 0.1–0.2 mm long, inside and base densely covered with ascending, very short hairs, sometimes glabrous, inner petals broadly rhombic, 2.5–2.8 by 2.2–3 mm, indument as on outer petals; stamens 15–17, in one whorl, free, oblong, 0.8–0.9 mm long, filaments 0.3–0.4 mm long, broader than connective, thecae latrorse, almost convergent apically, only leaving a very small part of the connective visible, connective slightly prolonged inward, glabrous, staminodes absent; carpels 6–9, ellipsoid, 1.3–1.4 by c. 0.6 mm, densely hairy, ovules 2 or 3, lateral, stigma deeply bifurcate, 0.2–0.5 mm long, glabrous. Monocarps and seeds not seen.

Distribution — Cameroon (South Region), Democratic Republic of the Congo (Orientale).

Habitat & Ecology — In swamp and secondary forests. Altitude: 470– 600 m. Flowering: March, April.

Preliminary IUCN conservation status — Endangered (EN): B2ab(iii). EOO: 68 251 km 2, AOO: 16 km 2. This species is known from only four localities outside reserves and has not been collected in the last 45 years.

Notes — 1. Monanthotaxis bicornis is closely related to Monanthotaxis pellegrinii based on the thecae almost converging apically; M. bicornis differs in having appressed, yellow-brown hairs (vs ascending reddish brown hairs).

2. Monanthotaxis bicornis can be distinguished from the other species with apically convergent thecae by the cuneate leaf bases and 15–17 stamens in one whorl.

Figures

Map 5 Distribution of Monanthotaxis bicornis Boutique (●, O means uncertain det) and M. biglandulosa (Boutique) P.H.Hoekstra (■).