Neostenanthera robsonii Le Thomas, Fl. Gabon No. 16: 196, 1969

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 : 275-277

Neostenanthera robsonii Le Thomas, Fl. Gabon No. 16: 196, 1969

Figs 83 , 84 ; Map 10G

Type.

Gabon. Ogooué-Lolo; Lastoursville, Le Testu G.M.P.C. 8635, 28 Dec 1930: lectotype, sheet here designated: BM[BM000553861]; isotypes: BM[BM000553860, BM000553862]; BR[BR0000008802705, BR0000008802378]; P[P00363316, P00363315] .

Description.

Tree, 5-25 m tall, d.b.h. 10-30 cm; stilt roots or buttresses absent. Indumentum of simple hairs; old leafless branches glabrous, young foliate branches tomentose, brown. Leaves: petiole 7-14 mm long, 1-3 mm in diameter, tomentose brown, slightly grooved to cylindrical, blade inserted on the side of the petiole; blade 7.5-31 cm long, 2.8-10.3 cm wide, oblong to elliptic, apex acuminate to acute, acumen 0.3-2.4 cm long, base rounded to obtuse, papyraceous, below densely pubescent with erect slight curly hairs when young and old, above glabrous when young and old, discolorous, whitish below; midrib impressed, above pubescent when young, glabrous when old, below pubescent when young and old; secondary veins 15 to 24 pairs, pubescent below; tertiary venation percurrent. Individuals bisexual; inflorescences cauliflorous or ramiflorous on old leafless branches, leaf opposed or extra axillary. Flowers with 9 perianth parts in 3 whorls, 2 to 8 per inflorescence, peduncle arbuscular-like, 8-26 mm long; pedicel 22-46 mm long, ca. 1 mm in diameter, pubescent; in fruit 30-60 mm long, 3-4 mm in diameter, pubescent; bract 1, basal, ca. 1 mm long, ca. 1 mm wide; sepals 3, valvate, free, ca. 1 mm long, 1-2 mm wide, semiorbicular, apex acuminate, base truncate, brown, pubescent outside, pubescent inside, margins flat; petals free, outer petals longer than inner; outer petals 3, 16.2-23.3 mm long, 3-4.6 mm wide, narrowly triangular, very thick, apex attenuate, base suborbicular and concave, brown, margins flat, pubescent to glabrous outside, densely pubescent inside; inner petals 3, valvate, 5.6-6 mm long, 1.4-2.9 mm wide, triangular, apex acute, base broad and concave, margins flat, pubescent outside, glabrous inside; stamens 160 to 170, in 5 to 6 rows, 2 mm long, linear; connective tongue shaped, glabrous, brown; staminodes absent; carpels free, ca. 144, ovary ca. 1 mm long, stigma filiform, glabrous. Monocarps stipitate, stipes 10-50 mm long, 1-2 mm in diameter; monocarps 19 to 144, 9-14 mm long, 5-10 mm in diameter, ellipsoid, apex apiculate, densely pubescent, smooth, not ribbed, brown when ripe; seed 1 per monocarp, 7-12 mm long, 4-8 mm in diameter, ellipsoid; aril absent.

Distribution.

Southern Cameroon and Gabon; in Cameroon known from the South region.

Habitat.

A rare species in Cameroon; in primary or old secondary rain forests on non-inundated soils. Altitude 200-800 m a.s.l.

Local and common names known in Cameroon.

None recorded.

IUCN conservation status.

Least Concern (LC) ( Cosiaux et al. 2019a e).

Uses in Cameroon.

None reported.

Notes.

Neostenanthera robsonii is distinguished by the brown tomentose indumentum covering most of its parts, and the usually cauliflorous inflorescences with arbuscular-like peduncles. This species was first considered endemic to Gabon ( Le Thomas 1969b), but has since been collected in Cameroon (e.g. Lachenaud 659, 2009).

Specimens examined.

South Region: Campo Ma'an National Park 11 km on trail from Ebinanemeyong village on road 7 km from Nyabessan to Campo town , 2.48°N, 10.33°E, 11 February 2015, Couvreur T.L.P. 675 (WAG,YA); Campo Ma'an National Park 11 km on trail from Ebinanemeyong village on road 7 km from Nyabessan to Campo town, 2.48°N, 10.34°E, 11 February 2015, Couvreur T.L.P. 678 (WAG,YA); Efoulan au sud d’Akom II (mi-chemin entre Ebolowa et Kribi), 2.76°N, 10.53°E, 09 May 2009, Lachenaud O.L. 659 (BR,BR,WAG,YA) .

Figures

Map 10. A Monodora myristica B Monodora tenuifolia C Monodora undulata D Monodora zenkeri E Neostenanthera myristicifolia F Neostenanthera neurosericea G Neostenanthera robsonii H Piptostigma calophyllum I Piptostigma fugax. White borders represent region limits in Cameroon; green patches represent protected areas (see methods and Suppl. material 1: Fig. S 1).

Figure 83. Neostenanthera neurosericea A trunk with flowers B base of leaf blade, upper side C base of leaf blade, lower side D flower, one inner petal folded showing the red staens and yellow carpels E flower, side view F fruits, note sessile and pyramidal monocarps. Neostenanthera robsonii G trunk with fruits H base of leaf blade, upper side I base of leaf blade, lower side J fruit with numerous monocarps, one monocarp longitudinally sectionned revealing single seed A-F Couvreur 603, Gabon G Couvreur 678, Campo Ma'an, Cameroon H-J Couvreur 1077, Gabon. Photos Thomas L. P. Couvreur.

Figure 84. Neostenanthera robsonii A leaf B detail of pubescence of leaf, lower side C infloresence D flower, outer petals removed E outer petal, inner view G inner petal inner and outer views H flower, top view I cauliflorous fruits A, B, J from Halle & Cours 6094 C-H from Le Testu 8635. Drawings by Helene Lamourdedieu, Publications Scientifiques du Museum national d'Histoire naturelle, Paris; modified from Le Thomas (1969 b, pl. 36, p. 195 and fig. 1, p. 197).