Monanthotaxis glaucifolia (Hutch. & Dalziel) 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 : 161

34. Monanthotaxis glaucifolia (Hutch. & Dalziel) P.H.Hoekstra — Map 16

Monanthotaxis glaucifolia (Hutch. & Dalziel) P.H.Hoekstra in Guo et al. (2017) 14. — Oxymitra glaucifolia Hutch. & Dalziel (1927b) 153. — Richella glaucifolia (Hutch. & Dalziel) R.E.Fr. (1959) 139. — Friesodielsia glaucifolia (Hutch. & Dalziel) Steenis (1964) 359. — Type: P.A. Talbot 403 (holo BM000843988), Nigeria, Cross River State, Oban, 1911.

Liana; young branches brown, densely covered with appressed to ascending, pale brown hairs 0.2–0.5 mm long, becoming glabrous; old branches dark brownish black. Leaves: petiole 4–7 mm long, 1.7–2.8 mm diam, terete, indument as on branches; lamina narrowly oblong-elliptic to oblanceolate, 11–25.8 by 3.7–8.6 cm, 2.6–3.8 times longer than wide, membranous to subcoriaceous, not punctate, glaucous to whitish below with blackish green venation, above glabrous, below glabrous or sometimes sparsely covered with pale-brown hairs c. 0.4 mm long, primary vein covered with pale brown hairs 0.1–0.3 mm long, base subcordate to narrowly subcordate, glands hardly visible, apex acuminate, acumen 5–25 mm long, primary vein reddish brown below in sicco, secondary veins 10–13 per side, first straight but slightly curving upwards at end near margin, tertiary venation percurrent, flat above. Inflorescences extra-axillary, leaf-opposed or sometimes terminal, composed of solitary flowers; sympodial rachis c. 1 mm long, densely covered with erect, yellow-brown hairs 0.2–0.3 mm long; pedicels 5–21 mm long, c. 1.4 mm diam, fruiting pedicels to 2.1 mm diam, indument as on sympodial rachis; lower bracts ovate, c. 2.5 by 1.6 mm; upper bract placed at the base of pedicel, broadly ovate, c. 3 by 2.4 mm, indument as on rachis; flower buds globose. Flowers bisexual; sepals free, depressed ovate, c. 4.5 by 7 mm, apex obtuse, densely covered with appressed, yellow-brown hairs; receptacle c. 5 mm diam, torus to 3 mm high, convex; petals colour in vivo unknown, 6, in two whorls, outer petals ovate, 30–35 by 23–25 mm, outside densely covered with appressed, yellow-brown hairs, inside glabrous except for some very short scattered hairs, inner petals rhombic, c. 21 by 26 mm, leaving open space at the base, outside sparsely covered with hairs 0.1–0.2 mm long, inside glabrous; stamens> 100, in five or six whorls, free, obconical, c. 1.3 mm long, filaments c. 0.5 mm long, thecae latrorse, connective truncate, rectangular seen from above, not hiding thecae, glabrous, staminodes absent; carpels 45–50, subcylindric to narrowly ellipsoid, 1.7–2 by c. 0.7 mm, densely covered with yellow hairs, ovules 2, lateral, stigma subsessile, globose, 0.1–0.2 mm diam, glabrous. Monocarps at least 8, colour in vivo unknown, ellipsoid, 1-seeded monocarps c. 15 by 9–10 mm, 2-seeded ones to 26 by 9–10 mm, smooth, densely covered with yellow-brown hairs 0.1–0.2 mm long, apex rounded to apiculate, stipes 3–4 mm long, slightly grooved. Seeds 1 or 2, ellipsoid, c. 10 by 8 mm, reddish brown to tawny-brown, raphe visible.

Distribution — Nigeria (Cross River State), Cameroon (South-West Region).

Habitat & Ecology — In submontane forest.Altitude: c. 950 m. Flowering: December.

Preliminary IUCN conservation status — Endangered (EN): B2ab(iii). AOO: 8 km 2. Monanthotaxis glaucifolia is known from 2 locations, of which the one near the Oban-Group Forest Reserve has not been collected in more than 100 years.

Note — Monanthotaxis glaucifolia closely resembles M. dielsiana and M. enghiana based on the flowers and leaf shape. It differs from M. dielsiana in having more than 100 stamens and by having pale brown hairs on the young branches, while M. dielsiana has orange-brown hairs and c. 65 stamens. Monanthotaxis enghiana differs from M. glaucifolia in having longer and erect hairs on the branches and leaves, M. enghiana generally has 2 –5 flowers per inflorescence and M. glaucifolia only one. Some specimens of M. enghiana , however, have less and more ascending instead of erect hairs, especially specimens at higher altitudes. More collections from the provinces bordering Cameroon and Nigeria are needed to verify if M. glaucifolia is merely a high-altitude variant of M. enghiana or if it is indeed a valid species. For now we refrain from synonymizing M. glaucifolia with M. enghiana .

Figures

Map 16 Distribution of Monanthotaxis elegans (Engl. & Diels) Verdc. (■, D means uncertain det) and M. glaucifolia (Hutch. & Dalziel) P.H.Hoekstra (●, O is uncertain det).