Hexalobus bussei Diels, Bot. Jahrb. Syst. 39: 479, 1907

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 : 119-121

Hexalobus bussei Diels, Bot. Jahrb. Syst. 39: 479, 1907

Fig. 30 ; Map 4E

= Hexalobus megalophyllus Engl. & Diels, Bot. Jahrb. Syst. 39: 479, 1907. Type. Cameroon. South Region, Bipindi, Zenker G.A. 2889, 1904: holotype: B[B100154197]; isotypes: BR[BR0000015306210]; COI[COI00033178]; F; G[G00011590]; HBG[HBG518920]; K[K000198935]; L[L-0049297]; M[M0089222]; MO[MO-2246481]; P[P00315838]; S[S12-22791]; US[00098767]; WAG[WAG0053629]; WRSL; WU[WU 0025867]; Z[Z-000000827].

Type.

Cameroon. South Region; Kribi, Busse W.C.O. 3216, 1904: holotype: B[B 10 0154198] .

Description.

Tree, 20-30 m tall, d.b.h. unknown; stilt roots or buttresses absent, trunk slender, not fluted. Indumentum of simple hairs; old leafless branches glabrous, young foliate branches pubescent. Leaves: petiole 1-7 mm long, 3-4 mm in diameter, pubescent, grooved, blade inserted on the side of the petiole; blade 15.5-36 cm long, 5.5-10 cm wide, obovate, apex acuminate, acumen 0.5-1 cm long, base cordate, coriaceous, below glabrous when young and old, above sparsely pubescent to glabrous when young, sparsely pubescent to glabrous when old, concolorous; midrib sunken or flat, above pubescent when young and old, below pubescent when young and old; secondary veins 12 to 17 pairs; tertiary venation reticulate. Individuals bisexual; inflorescences ramiflorous on old leafless or young foliate branches, axillary. Flowers with 9 perianth parts in 2 whorls, 1 to 2 per inflorescence; pedicel 10-12 mm long, 4-5 mm in diameter, densely pubescent; in fruit 10-13 mm long, 2-3 mm in diameter, glabrous; bracts 5 to 6, several basal and two (sometimes fused) towards the upper half of pedicel, basal bracts 3-9 mm long, 2-5 mm wide; upper bracts 6-13 mm long, 2-3 mm wide; sepals 3, valvate, free, 16-20 mm long, 11-14 mm wide, ovate, apex acute, base truncate, brown, densely pubescent outside, glabrous inside, margins flat; petals basally fused, tube 2-5 mm long, purple, inner and outer whorl not differentiated, equal, lobes 23-40 mm long, 8-10 mm wide, elliptic, apex rounded, pale yellow, margins wavy, densely pubescent outside, densely pubescent inside, plicate; stamens numerous, 7-8 mm long, elongated; connective elongated, glabrous; staminodes absent; carpels free, 3 to 7, ovary 4-5 mm long, stigma elongate, pubescent. Monocarps stipitate, ca. 1 mm long, ca. 3 mm in diameter; monocarps 2 to 4, 53-78 mm long, ca. 40 mm in diameter, ellipsoid, apex rounded, sparsely pubescent, rugose, irregularly ribbed in reticulate pattern, orange when ripe; seeds 17 to 19 per monocarp, 23-28 mm long, 17-19 mm in diameter, flattened ellipsoid; aril absent.

Distribution.

endemic to Cameroon; known from the South region.

Habitat.

A rare species, in primary lowland rain forests, sometimes riverine. Altitude 0-200 m a.s.l.

Local and common names known in Cameroon.

None recorded.

IUCN conservation status.

Endangered (EN) ( Cosiaux et al. 2019l).

Uses in Cameroon.

None recorded.

Notes.

Hexalobus bussei is distinguished by its large leaf blades (15-36 cm long) and the irregularly ridged and strongly rugose surface of its monocarps.

Specimens examined.

South Region: S bank of Kienke river just E of Kribi, 3.1°N, 10.25°E, 12 May 1969, Bos J.J. 4495 (P,WAG); 21 km from Kribi high forest exploitation N of Lolodorf road, 3.03°N, 10.05°E, 07 August 1969, Bos J.J. 5157 (BR,P,WAG,YA); ca 16 km from Kribi Lolodorf road, 3°N, 10.01°E, 19 September 1969, Bos J.J. 5370 (BR,C,K,LD,LM,MO,P,WAG,YA); Kribi, 2.95°N, 9.916°E, 01 September 1904, Busse W.C.O. 3216 (B); 31 km ESE Kribi N of Kienke River Nyabessan, 2.9°N, 10.16°E, 19 April 1968, Letouzey R. 9387 (P,YA); Bipindi, 3.08°N, 10.42°E, 01 January 1904, Zenker G.A. 2889 (B,BR,COI,F,G,L,M,MO,P,S,WAG); Bipindi, 3.08°N, 10.42°E, 26 October 1908, Zenker G.A. 3550 (BR,COI,G,M,MO,P,S); Bipindi, 3.08°N, 10.41°E, 01 January 1908, Zenker G.A. 3592 (G,K); Bipindi, 3.08°N, 10.41°E, 01 January 1909, Zenker G.A. 3889 (BR,COI,G,K,L,M,MO,P,S); Bipindi, 3.08°N, 10.42°E, 01 January 1913, Zenker G.A. 4831 (BR,G,P,S) .

Figures

Map 4. A Duguetia dilabens B Duguetia staudtii C Greenwayodendron glabrum D Greenwayodendron suaveolens E Hexalobus bussei F Hexalobus crispiflorus G Hexalobus monopetalus H Hexalobus salicifolius I Isolona campanulata. White borders represent region limits in Cameroon; green patches represent protected areas (see methods and Suppl. material 1: Fig. S 1).

Figure 30. Hexalobus bussei A flowering branch B stamen, front view. Hexalobus monopetalus C flowering branch D opened flower, one sepal and one petal removed E stamen, front view F portion of pedicel with three monocarps A, B from Zenker 3550 C-E from Letouzey 7301 F from Chevalier 305. Drawings by Helene Lamourdedieu, Publications Scientifiques du Museum national d'Histoire naturelle, Paris; modified from Botermans et al. (2011, fig. 3, p. 35).