Monanthotaxis enghiana (Diels) P.H.Hoekstra

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 : 150-152

25. Monanthotaxis enghiana (Diels) P.H.Hoekstra — Fig. 11; Plate 3b ; Map 17

Monanthotaxis enghiana (Diels) P.H.Hoekstra in Guo et al. (2017) 14. — Popowia enghiana Diels in Mildbr. (1911) 213. — Friesodielsia enghiana (Diels) Verdc. in Le Thomas (1969) 240. — Type: G.W.J. Mildbraed 2213 (holo B100153056), Democratic Republic of the Congo, Nord-Kivu, Fort Beni a Semliki, 1907–1908.

Unona obanensis Baker f.(1913) 4. — Oxymitra obanensis (Baker f.) Sprague & Hutch. (1916) 154. — Richella obanensis (Baker f.) R.E.Fr. in Engl. & Harms (1959) 139. — Friesodielsia obanensis (Baker f.) Steenis (1964) 359. — Type: P.A. Talbot 1246 (holo BM000547069), Nigeria, Cross River State, Oban, 1911.

Oxymitra grandiflora Boutique (1951b) 116. — Richella grandiflora (Boutique) R.E.Fr. in Engl.& Harms (1959) 139. — Friesodielsia grandiflora (Boutique) Steenis (1964) 359. — Lectotype (designated here): R.G.A. Germain 883 (lecto BR; iso K000913652, K000913653, MO), Democratic Republic of the Congo, Orientale, Yalibutu, 45 km NW of Yangambi, 22 Jan. 1948.

Popowia mangenotii Sillans (1953) 578. — Lectotype (designated here): C. Tisserant (Équipe) 1285 (lecto P ( P00363339 ); iso BR, K000913654 , P00363338 ), Central African Republic, Lobaye, Station de Boukoko, Boukokok , 14 Dec. 1948.

Popowia mangenotii Sillans f. concolor Sillans (1953) 580. — Lectotype (designated here): C. Tisserant (Équipe) 2062 (lecto P ( P00363336 ); iso BM000547068 , BR, P003633385 , P01985781 ), Central African Republic, Lobaye, Station de Boukoko, Boukokok , 5 Apr. 1951.

Shrub, scandent shrub or liana, to 15 m long, to 6 cm diam; young branches densely covered with erect, dark brown hairs 0.9–1.4 mm long, becoming glabrous; old branches dull silverygrey, drying black. Leaves: petiole 3–4 mm long, 1.3–2.2 mm diam, terete, indument as on branches; lamina narrowly oblong-oblanceolate, 10.8–35 by 3.3–7.5 cm, (2.2–)3–4.4(–5.9) times longer than wide, membranous to subcoriaceous, not punctate, discolorous, slightly bright to pale green above, glaucous below, above sparsely covered with appressed, whitish hairs c. 0.7 mm long, soon becoming glabrous, primary vein densely covered with erect hairs, below rather densely covered with erect, brown hairs 0.5–0.8 mm long, more densely so on the primary vein, base rounded to subcordate, glands hardly visible, apex acute to acuminate, acumen to 50 mm long, secondary veins 11–20 per side, curving upwards near margin, tertiary venation distinctly percurrent, not raised above. Inflorescences extra-axillary or sometimes supra-axillary, composed of corymb-like (1–)2–5-flowered rhipidia; sympodial rachis 3–12 mm long, densely covered with hairs, flowering and fruiting pedicels

b

Fig. 11 Monanthotaxis enghiana (Diels) P.H.Hoekstra. a. Fruiting branch; b. detail leaf abaxially; c. inflorescence; d. outer petal; e. inner petal; f. flower with petals removed; g. stamen, front and side view; h. carpel and longitudinal section of carpel; i. longitudinal section of carpel; j. transverse section of carpel (a, i–j: Sillans 1701; b–h: Tisserant 1941). — Modified from Le Thomas (1969) plate 43.

18–22 mm long, 0.6–1.8 mm diam, densely covered with ascending to erect hairs; lower bracts broadly ovate 1.5–2 by 1.5–2.5 mm, indument as on pedicels; upper bract halfway or at one-third of the pedicel, broadly ovate, 2.7–4.5 by 3.5–4 mm, semi-amplexicaul, outside glabrous, inside densely covered with hairs; flower buds globose. Flowers bisexual; sepals connate at the base, depressed ovate, 2.5–5 by 4.7–8 mm, apex rounded, densely covered with appressed, dull brown hairs, persistent in fruit; receptacle convex; petals dull black, purplish brown in sicco, 6, in two whorls, outer petals ovate to elliptic, 12– 22 by 7–14 mm, outside densely covered with yellow-brown hairs, inside covered with reddish, short hairs at the apex, glabrous at the base, inner petals ovate-rhombic, 9–14 by 8–10 mm, outside and inside glabrous, sometimes with few, solitary hairs at the base; stamens 90–110, in three or four whorls, free, obconical, 1.2–1.3 mm long, filaments c. 0.4 mm long, thecae latrorse, connective truncate, rectangular from above, prolonged inward and outward, hiding thecae, glabrous, staminodes absent; carpels 40–60, subcylindric, c. 2.9 by 0.5 mm, densely hairy, ovules 2(–4), lateral, stigma elongate, c. 1 mm long, glabrous. Monocarps 5–15, glaucous green, ellipsoid, 14–34 by 8–9 mm, densely covered with brown hairs, apex rounded to apiculate, stipes 2–5 mm long. Seeds 1–2(–3), ellipsoid, 11–12 by 7–11 mm, tawny to reddish brown, ends rounded, raphe slightly visible on both sides.

Distribution — Guinea, Sierra Leone, Liberia, Ivory Coast, Ghana, Nigeria, Cameroon, Equatorial Guinea, Gabon, Republic of the Congo, Central African Republic, Democratic Republic of the Congo, Uganda.

Habitat & Ecology — In evergreen primary forest, moist semi-deciduous forest, submontane forest, secondary forest, gallery forest, swamp forest, on rocky soil.Altitude: 0–1375 m. Flowering: October to July; fruiting: October to July.

Vernacular names — Cameroon: Mavembegne (Pygmée name) (R.G. Letouzey 5071). Central African Republic: Mo-Fembe Fembe (Lissongo name) (C. Tisserant (Équipe) 2062), Fembe (Lissongo name) (C. Tisserant (Équipe) 1701), Molo-Mindowali (Lissongo name) (C. Tisserant (Équipe) 1257), Vembenye (Bambindjere name) (D.J. Harris 1721). Democratic Republic of the Congo: Lukumbula (Kirega and Kitembe name) (A.R. Christiaensen 1802, G.M.D.J. Troupin 12466). Amàphaphasà (Kikumu name) (J. Bokdam 3574). Amapapasia (C.E.N. Ewango 258), Esaa (Babua name) (P. Gérard 517), Etumu (Mukire name) (J. Claessens 629). Impimbo ya pembe (Nkundo name) (B.I. Fruth 1894), Impimbo ya dzamba (Nkundo name) (B.I. Fruth 123). Gabon: Maboom-Mamiala (Bongom name) (J.J. Wieringa 3605).

Preliminary IUCN conservation status — Least concern (LC). EOO: 4 370 609 km 2, AOO: 468 km 2. This species occurs in many countries, locations and reserves. In the wet tropical forests of Central and West Africa this probably is the most common species of Monanthotaxis .

Note — Monanthotaxis enghiana is generally easily recognizable by the narrowly oblong-oblanceolate leaves with a dense indument of erect, dark brown, long hairs on the young branches and lower side of the leaves. Some sterile specimens can have more narrowly oblong-elliptic leaves, and are not distinguishable with certainty from M. hirsuta . However, the petals and stamens of M. enghiana are very different from those of M. hirsuta . The outer petals of M. enghiana are shorter (12–22 mm vs 21–50 mm in M. hirsuta ) and the inner petals of M. enghiana are ovate-rhombic (vs lanceolate). The thecae of M. enghiana are very short, they cover less than half the stamen length, while in M. hirsuta the thecae cover much more than half the stamen length. Monanthotaxis enghiana is closely related to M. dielsiana and M. glaucifolia , but differs clearly in the indument type. See the notes under those species.

Figures

Plate 3 a. Monanthotaxis discrepantinervia Verdc. Flowering branch. — b. Monanthotaxis enghiana (Diels) P.H.Hoekstra. Leaves. — c. Monanthotaxis filamentosa (Diels) Verdc. Flower. — d. Monanthotaxis foliosa (Engl. & Diels) Verdc. Flowering branch. — e. Monanthotaxis glabra P.H.Hoekstra.Leaves and fruit. — f. Monanthotaxis hirsuta (Benth.) P.H.Hoekstra. Flowers (a: Couvreur 94; b: not collected; c: Letouzey 14591; d: Couvreur 601; e: Jongkind 7965; f: Jongkind 8836). — Photos: a, d: T.L.P. Couvreur; b, e–f: C.C.H. Jongkind; c: P.H. Hoekstra.

Map 17 Distributin of Monanthotaxis enghiana (Diels) P.H.Hoekstra.