Isolona dewevrei (De Wild. & T. Durand) Engl. & Diels, Monogr. Afrik. Pflanzen.-Fam. 6: 83, 1901

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 : 139-141

Isolona dewevrei (De Wild. & T. Durand) Engl. & Diels, Monogr. Afrik. Pflanzen.-Fam. 6: 83, 1901

Fig. 36 ; Map 5C

≡ Monodora dewevrei De Wild. & T. Durand, Bull. Soc. Roy. Bot. Belg., Compt. Rend. 38: 11, 1899.

Type.

Democratic Republic of the Congo. Bas Congo; Lemba-Luki, Dewèvre A.P. 365, no date: lectotype, sheet here designated: BR[BR0000008801050]; isotypes: BR[BR0000008799968, BR0000008800725, BR0000008799630] .

Description.

Tree to shrub, 8-15 m tall, d.b.h. 20 cm; stilt roots or buttresses absent. Indumentum of simple hairs; old leafless branches glabrous, young foliate branches glabrous. Leaves: petiole 4-15 mm long, 1-2 mm in diameter, glabrous, grooved, blade inserted on the side of the petiole; blade 10-17 cm long, 4-7 cm wide, elliptic to obovate, apex acuminate, acumen ca. 1 cm long, base decurrent to cuneate, papyraceous, below glabrous when young and old, above glabrous when young and old, concolorous; midrib raised, above glabrous when young and old, below glabrous when young and old; secondary veins 9 to 14 pairs, glabrous below; tertiary venation reticulate. Individuals bisexual; inflorescences ramiflorous on old branches, axillary. Flowers with 9 perianth parts in 2 whorls, 1 per inflorescence; pedicel 2-7 mm long, 1 mm in diameter, sparsely pubescent; in fruit 9-10 mm long, 2-3 mm in diameter, glabrous; bracts 3 to 5, several basal and one upper towards the lower half of pedicel, basal bracts 1 mm long, 0.5-1 mm wide; upper bract 1 mm long, 1 mm wide; sepals 3, valvate, free, 2-3 mm long, 3-4 mm wide, ovate, apex acuminate, base truncate, glabrous outside, glabrous inside, margins flat; petals basally fused, tube 3-4 mm long, inner and outer whorl not differentiated, equal; lobes 7-17 mm long, 5-7 mm wide, elliptic, apex rounded, green, margins flat, overall glabrous but pubescent towards margins outside and inside; margins curved outwards; stamens ca. 50, in 3 to 4 rows, 2 mm long, broad; connective discoid, glabrous; staminodes absent; carpels fused into a single structure, ca. 1 mm long, stigma capitate, glabrous. Fruit syncarpous, sessile, 60-70 mm long, 40-50 mm in diameter, ovoid, apex rounded, glabrous, smooth, not ribbed, green when ripe; seeds not counted, 10-20 mm long, 10-15 mm in diameter, ellipsoid; aril absent.

Distribution.

A widespread species, but with few overall specimens, from Liberia to Nigeria, and from Cameroon to Democratic Republic of Congo; in Cameroon in the South and South-West regions.

Habitat.

A rare species in Cameroon known from two specimens; in lowland primary and secondary forests. Altitude 0-860 m a.s.l.

Local and common names known in Cameroon.

None recorded.

IUCN conservation status.

Least Concern (LC) ( Cosiaux et al. 2019s).

Uses in Cameroon.

None reported.

Notes.

Isolona dewevrei resembles I. thonneri in leaf and fruit shape, but the former can be distinguished by its elliptic and shorter corolla lobes with hairy margins and its flowering pedicel sparsely covered with short hairs. It is, however, very hard to distinguish both species apart based on fruit or vegetative characters alone.

Specimens examined.

South Region: Ngongondje hill near Akonetye 2 30'S of Ebolowa, 2.5°N, 11.13°E, 28 August 1979, Koufani A. 123 (P,YA). South-West Region: Piste Munkep-Gayama 40 km NNW Wum, 6.73°N, 9.95°E, 08 July 1975, Letouzey R. 13984 (K,MO,YA) .

Figures

Map 5. A Isolona congolana B Isolona cooperi C Isolona dewevrei D Isolona hexaloba E Isolona pilosa F Isolona pleurocarpa G Isolona thonneri H Isolona zenkeri I Letestudoxa bella. White borders represent region limits in Cameroon; green patches represent protected areas (see methods and Suppl. material 1: Fig. S 1).

Figure 36. Isolona dewevrei A flowering branch B flower (side view) C flower top view D transversal section of flower E detail of stig top view F transversal section of seed G fruit (left) and longitudinal section of fruit (right) H seed, side view (top), detail of hilum (bottom). Modified from Ake Assi (1963, fig. 1, p. 14).