Monanthotaxis dielsiana (Engl.) P.H.Hoekstra, Taxon 66: 14, 2017

Couvreur, Thomas L. P., Dagallier, Leo-Paul M. J., Crozier, Francoise, Ghogue, Jean-Paul, Hoekstra, Paul H., Kamdem, Narcisse G., Johnson, David M., Murray, Nancy A. & Sonke, Bonaventure, 2022, Flora of Cameroon - Annonaceae Vol 45, PhytoKeys 207, pp. 1-532 : 188-191

Monanthotaxis dielsiana (Engl.) P.H.Hoekstra, Taxon 66: 14, 2017

Map 7B

≡ Unona dielsiana Engl., Bot. Jahrb. Syst. 39(3-4): 476, 1907. Oxymitra dielsiana (Engl.) Sprague & Hutch.Bull. Misc. Inform. Kew 6: 156, 1916; Richella dielsiana (Engl.) R.E.Fr., in Engler & Prantl Nat. Pflanzenfam., ed. 2, 17a (2): 139, 1959; Friesodielsia dielsiana (Engl.) Steenis, Blumea 12: 359, 1964.

Type.

Cameroon. South Region; Bipindi, Zenker G.A. 2473, Dec 1901: lectotype, chosen by Hoekstra et al. (2021), p. 147: B[B100154098]; isolectotypes: B[B100154096, B100154097, B100154099]; BM[BM001125043]; BR[BR000008801388]; COI[COI00071518]; E; G[G00308364]; GOET[GOET005688, GOET005689]; HBG[HBG502481]; K[K000198948]; KFTA[KFTA 0001554, KFTA 0001555]; L[L 0182291]; M[M-0240178]; P[P00363342, P00363343, P01988326]; S[S07-13404]; WAG[WAG0057970]; WU[WU 0025876] .

Description.

Liana, height unknown, d.b.h. unknown. Indumentum of simple hairs; old leafless branches glabrescent, young foliate branches densely pubescent with orange-brown hairs ca. 0.5 mm long. Leaves: petiole 6-11 mm long, ca. 2 mm in diameter, densely pubescent, grooved, blade inserted on top of the petiole; blade 10.5-21.5 cm long, 3.5-4 cm wide, narrowly oblong to oblanceolate, apex acuminate, acumen 0.5-2.5 cm long, base subcordate, subcoriaceous to membranous, below glabrous when young and old, above glabrous when young and old, discolorous, whitish below; midrib impressed, above sparsely pubescent when young and old, below sparsely pubescent when young and old; secondary veins 7 to 14 pairs, glabrous above; tertiary venation percurrent. Individuals bisexual; inflorescences ramiflorous on old leafless branches, leaf opposed. Flowers with 9 perianth parts in 3 whorls, 1 to 3 per inflorescence, pedicel 15-27 mm long, 1-2 mm in diameter, pubescent; in fruit 15-30 mm long, ca. 3 mm in diameter, pubescent; basal bract ca. 4 mm long, ca. 4 mm wide; upper bract ca. 5 mm long, ca. 4 mm wide; sepals 3, valvate, free, ca. 4 mm long, ca. 4 mm wide, triangular, apex acute, base truncate, densely pubescent outside, glabrous inside, margins flat; petals free, outer petals longer than inner, inner petals entirely covered in bud; outer petals 3, 10-15 mm long, 8-9 mm wide, ovate, apex obtuse, base truncate, margins flat, densely pubescent outside, glabrous inside; inner petals 3, valvate, ca. 8 mm long, ca. 8 mm wide, broadly ovate, apex obtuse, base truncate, margins flat, pubescent outside, glabrous inside; stamens ca. 65, in 3 rows, ca. 0.5 mm long, cylindrical; connective rounded, glabrous; staminodes absent; carpels free, ca. 41, ovary ca. 2 mm long, stigma globose, glabrous. Monocarps stipitate, stipes ca. 3 mm long, ca. 2 mm in diameter; monocarps ca. 6, ca. 45 mm long, 10-12 mm in diameter, moniliform, ellipsoid to cylindrical, apex rounded, densely pubescent, rugulose, constricted around seeds when more than 1, brown when unripe; seeds 1 to 2 per monocarp, ca. 15 mm long, ca. 9 mm in diameter, subcylindrical; aril absent.

Distribution.

endemic to Cameroon; known from the Central and South regions.

Habitat.

A rare species, known from two collections; in primary rain forests. Altitude 0-200 m a.s.l.

Local and common names known in Cameroon.

None recorded.

Preliminary IUCN conservation status.

Critically Endangered (CR) ( Hoekstra et al. 2021).

Uses in Cameroon.

None reported.

Notes.

Monanthotaxis dielsiana is distinguished by its dense yellow to orange-brown appressed pubescence on the young foliate branches, and flowers with around 65 stamens. It resembles M. enghiana and M. glaucifolia by the overall morphology of the flowers and leaves, but M. enghiana has longer erect hairs and M. glaucifolia has denser light-brown appressed hairs; in addition, M. enghiana and M. glaucifolia have many more stamens (more than 90).

Specimens examined.

Central Region: 60 km SW of Eséka S of Nyong R 12 km W of Songbong , 3.47°N, 10.5°E, 10 March 1965, Leeuwenberg A.J.M. 5088 (BR,K,MO,P,WAG,YA). South Region : Bipindi, 3.08°N, 10.41°E, 01 January 1902, Zenker G.A. 2473 (L,P,WAG) .

Figures

Map 7. A Monanthotaxis diclina B Monanthotaxis dielsiana C Monanthotaxis elegans D Monanthotaxis enghiana E Monanthotaxis ferruginea F Monanthotaxis filamentosa G Monanthotaxis foliosa H Monanthotaxis glaucifolia I Monanthotaxis gracilis. White borders represent region limits in Cameroon; green patches represent protected areas (see methods and Suppl. material 1: Fig. S 1).