Monanthotaxis nimbana (Schnell) 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 : 182

52. Monanthotaxis nimbana (Schnell) Verdc. — Map 31

Monanthotaxis nimbana (Schnell) Verdc. (1971b) 27. — Popowia nimbana Schnell (1953) 93. — Type: R.A.A. Schnell 5202 (holo consisting of 2 sheets: P00362636 , P00362637 ), Guinea, Nzérékoré, forêt montagneuse du Nimba, forêt des crêtes du Nimba S. W., Apr. 1950 .

Scandent shrub or liana, to 5 m long; young branches densely covered with appressed, reddish brown hairs 0.1–0.2 mm long, becoming glabrous, old branches blackish brown. Leaves: petiole 2–8 mm long, 0.6–0.9 mm diam, terete, indument as on branches; lamina narrowly oblong-elliptic to narrowly obovate, 4.9–12.6 by 1.7–4.1 cm, 2.5–3.4 times longer than wide, chartaceous, not punctate, pale bluish green below, above sparsely covered with appressed, white hairs 0.4–0.5 mm long, primary vein hairs more densely covered with yellowish and longer persistent hairs, becoming glabrous, below sparsely covered with appressed, yellowish hairs 0.1–0.3 mm long, base rounded to slightly subcordate, with thickened black margin, apex acute to acuminate, acumen to 15 mm long, secondary veins 9–13 per side, curving, tertiary venation percurrent. Inflorescences axillary or terminal, composed of solitary flowers; sympodial rachis absent; flowering and fruiting pedicels 9–45 mm long, 0.3–0.5 mm diam, sparsely covered with appressed, yellowish hairs; lower bract absent; upper bract in upper half of the pedicel, ovate to lanceolate, 0.7–1.8 by 0.3–0.6 mm, indument as on pedicel; flower buds globose. Flowers bisexual; sepals free, broadly ovate, 1–1.3 by 0.9–1.4 mm, apex acute, densely covered with appressed hairs, persistent in fruit; receptacle c. 1.5 mm diam, flat; petals colour in vivo unknown, 6, in two whorls, base of inner petals visible in bud, outer petals broadly ovate, 2.1–3.5 by 1.9–3.3 mm, outside and apical part and margins on the inside covered with yellow hairs, inner petals elliptic, 1.5–3.4 by 0.9–2.1 mm, indument as on outer petals; stamens 16–18, in two whorls, free, linear-oblong, 0.8–1.2 mm long, filaments c. 0.6 mm long, thecae introrse, connective truncate, prolonged outward, not hiding thecae, glabrous or sometimes hairy, staminodes absent; carpels 2–5, ellipsoid, 1.1–1.2 by c. 0.7 mm, densely hairy, ovule 1, basal, stigma elongate, 0.4–0.5 mm long, glabrous. Monocarps 1–5, orange, ellipsoid to narrowly ellipsoid, 12–18 by 5.5–6 mm, slightly verrucose, densely covered with appressed, white-yellowish hairs, becoming glabrous, apex apiculate, apiculum to 0.5 mm long, stipes 1–5 mm long. Seed 1, ellipsoid, 8.5–10 by 5.5–6 mm, ochre-brown, apex rounded, raphe visible.

Distribution — Guinea, Sierra Leone, Liberia, Ivory Coast.

Habitat & Ecology — In montane forest, gallery forest and sub-montane scrub, on rocky soils, steep slopes and hill-crests. Altitude: 700–1615 m. Flowering: January to August; fruiting: June to March.

Preliminary IUCN conservation status — Least concern (LC). EOO: 49 713 km 2, AOO: 112 km 2. This species is common in the Nimba mountains and some other mountain ridges in the south of Guinea. It must, however, be noted that this species has not been collected in Sierra Leone in the last 50 years.

Notes — 1. Monanthotaxis nimbana is the only species of Monanthotaxis with axillary inflorescences, the stamens in two whorls and with 2–5 carpels per flower. Most specimens can be readily recognised by having fruits with only 1–3 1-seeded monocarps.

2. Some specimens from Mount Loma in Sierra Leone are different from the majority of specimens in having shorter pedicels, 8–15 mm long, and narrowly obovate leaves and the only specimen with flowers has small hairs on the connectives; however, there are also specimens with longer pedicels and oblong-elliptic leaves on Mount Loma. More material is needed in combination with phylogenetic analyses of molecular characters to define if that population belongs to a different entity.

Figures

Map 31 Distribution of Monanthotaxis mannii (Baill.) Verdc.(■) and M. nimbana (Schnell) Verdc. (●).