Monanthotaxis tripetala 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 : 205-206

72. Monanthotaxis tripetala P.H.Hoekstra — Fig. 31 ; Map 45

Monanthotaxis tripetala P.H.Hoekstra in Hoekstra et al. (2016) 96. — Type: A.J.M. Leeuwenberg 5828 (holo consisting of 2 sheets: WAG0110801 , WAG0110802 ; iso B100190273 , BR0000014126253 , C not seen, EA, K, LISC not seen, MO not seen, P01967268 , PRE not seen, YA not seen), Cameroon, East Province , 15 km E of Dimako, village halfway Bertoua- Doumé, 650 m, 11 June 1965.

Liana, at least 10 m long, c. 11 cm diam; young branches covered with appressed, reddish brown hairs c. 0.1 mm long, becoming glabrous; old branches dark brown, with few lenticels. Leaves: petiole 2–8 mm long, 0.6–1.5 mm diam, slightly grooved, indument as on branches; lamina oblong-elliptic to narrowly oblong-elliptic, 4.2–16.2 by 1.8–5.3 cm, 1.8–3 times longer than wide, subcoriaceous, not punctate, discolorous, glossy dark green above, dull greenish white below, young leaves above sparsely covered with appressed, white hairs, becoming glabrous, primary vein covered with appressed, yellowish hairs, becoming glabrous, below sparsely covered with appressed, white hairs 0.1–0.2 mm long, becoming glabrous, primary vein more densely covered with yellowish hairs, base rounded, with thick globose glands, apex acute to acuminate, acumen to 5 mm long, secondary veins 7–10 per side, from base curving upwards, tertiary venation percurrent, not visible above. Inflorescences axillary, composed of solitary flowers or a 2-flowered rhipidia; sympodial rachis 0–6 mm long, covered with appressed, yellowish hairs; pedicels 12–20 mm long, 0.2– 0.4 mm diam, fruiting pedicels 16–29 mm long, 1.5–2.2 mm diam, covered with appressed, yellowish hairs; lower bract absent; upper bract in the upper half of the pedicel or absent, ovate, c. 0.5 by 0.2 mm, densely covered with yellowish hairs; flower buds globose. Flowers bisexual; sepals free, depressed ovate, c. 0.5 by 0.8–1 mm, apex obtuse, densely covered with appressed, yellow hairs, not persistent in fruit; receptacle c. 1.5 mm diam, flat; petals colour in vivo unknown, 3 (or 4) in one (or two) whorls, outer petals broadly ovate, 2–2.2 by c. 2.2 mm, outside covered with appressed, yellowish hairs, apex of inside papillate, inner petals usually absent, rarely a single strongly reduced petal present, narrowly elliptic, c. 1.5 by 0.5–0.6 mm, outside and base of inside sparsely covered with yellowish papillae; stamens 9–12, in one whorl, free, linearclavate, c. 1.2 mm long, filaments c. 0.6 mm long, thecae ex-

Map 45 Distribution of Monanthotaxis tripetala P.H.Hoekstra (●), M. wieringae P.H.Hoekstra (■) and M. zenkeri P.H.Hoekstra (▲).

trorse to latrorse, connective truncate, prolongation not hiding thecae, glabrous, staminodes absent; carpels c. 9, subcylindric to ellipsoid, 1.1–1.2 by 0.3–0.4 mm, densely hairy, ovules 3 or 4, lateral, stigma subsessile, subglobose, 0.1–0.2 mm long, glabrous. Monocarps 7, yellow, moniliform, each part narrowly ellipsoid, 110–130 by 7.5–8.5 mm, verrucose, sparsely covered with appressed, short hairs, apex apiculate, apiculum 5–8 mm long, stipes 7–22 mm long. Seeds 1–4, ellipsoid, c. 17 by 7 mm, reddish brown, apex apiculate, raphe visible.

Distribution — Cameroon (East province), Gabon (Ogooué-Ivindo).

Habitat & Ecology — In evergreen forest and old secondary forest on hill side.Altitude: 391– 895 m. Flowering: June; fruiting: October.

Preliminary IUCN conservation status — Endangered (ED): B2ab(iii). EOO: 38 735 km 2, AOO: 24 km 2. This species is known from 6 collections from 4 locations of which one is a protected area. The other locations are under threat of mining companies or by an increasing human population growth.

Note — Monanthotaxis tripetala can be recognized by the small axillary flowers of which the inner petals are highly reduced have

Figures

Fig. 31 Monanthotaxis tripetala P.H.Hoekstra. a. Flowering branch; b. leaf base abaxially; c. leaf base and inflorescence; d. flower with one petal removed; e. petal, inside view; f. flower with petals removed; g. stamen, outside view; h. stamen, inside view; i. stamen, side view; j. carpel (all: Leeuwenberg 5828, WAG). — Drawing by H. de Vries.