Isolona pleurocarpa Diels, Bot. Jahrb. Syst. 39: 485, 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 : 147-148

Isolona pleurocarpa Diels, Bot. Jahrb. Syst. 39: 485, 1907

Fig. 38 ; Map 5F

= Isolona leucantha Diels, Bot. Jahrb. Syst. 39: 484, 1907. Type. Cameroon. South Region, Bipindi, Zenker G.A. 3038, Apr 1904: holotype: B[B 10 0154212]; isotypes: BM[BM000546385]; BR[BR0000008802644]; COI[COI00077204]; E[E00259306]; G[G00011566]; GOET[GOET005681]; HBG[HBG518922]; K[K000199011]; L[L-0182762]; M[M0089224]; MO[M0089224]; P[P00363267]; S[S-G-7462]; WAG[WAG0000090]; WU[WU0025864].

Type.

Cameroon. South Region; Bipindi, Zenker G.A. 3217, Jul 1904: holotype: B[B 10 0154211]; isotypes BR[BR0000008498991]; G[G00011576 G00011761]; K[K000198837]; S[S10-21236]; WU[WU0025885] .

Description.

Tree, 15-30 m tall, d.b.h. up to 60 cm; stilt roots or buttresses absent, trunk fluted. Indumentum of simple hairs; old leafless branches glabrous, young foliate branches glabrous. Leaves: petiole 4-12 mm long, 1 mm in diameter, glabrous, grooved towards the base, blade inserted on the side of the petiole; blade 8.5-15.5 cm long, 3-6 cm wide, elliptic to obovate, apex acuminate, acumen 1-1.5 cm long, base decurrent to cuneate, papyraceous to subcoriaceous, below glabrous when young and old, above glabrous when young and old, concolorous; midrib raised above, above glabrous when young and old, below glabrous when young and old; secondary veins 9 to 12 pairs, glabrous below; tertiary venation reticulate. Individuals bisexual; inflorescences ramiflorous on old or young foliate branches, axillary. Flowers with 9 perianth parts in 2 whorls, 1 per inflorescence; pedicel 1-2 mm long, 1 mm in diameter, glabrous; in fruit 30 mm long, 3-4 mm in diameter, glabrous; bracts 3 to 7, several basal and one upper towards the lower half of pedicel, basal bracts ca. 1 mm long, ca. 1 mm wide; upper bracts ca. 1 mm long, ca. 1 mm wide; sepals 3, valvate, free, 2-3 mm long, 2-3 mm wide, ovate, apex acuminate, base truncate, green, glabrous outside, glabrous inside, margins flat; petals basally fused, tube 6-15 mm long, red, inner and outer whorl not differentiated, equal; lobes 10-23 mm long, 5-10 mm wide, ovate, apex acute, bright green-white to yellow, margins wavy, glabrous outside, glabrous inside, spreading horizontally; stamens numerous, in 3 to 4 rows, ca. 2 mm long, broad; connective discoid, glabrous, yellow; staminodes absent; carpels fused into a single structure, ca. 2 mm long, stigma bilobed, slightly capitate, glabrous. Fruit syncarpous, sessile, ca. 50 mm long, ca. 40 mm in diameter, globose, apex rounded, glabrous, rugulose, longitudinally 6-8 ribbed, green when unripe; seeds not counted, 8-10 mm long, 5-7 mm in diameter, ellipsoid; aril absent.

Distribution.

Known from Nigeria and Cameroon; in Cameroon known from the South and South-West regions.

Habitat.

An infrequent species; in lowland rain forests on non-inundated soils. Altitude 0-550 m a.s.l.

Local and common names known in Cameroon.

Avom (van Andel 4177).

IUCN conservation status.

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

Uses in Cameroon.

None reported.

Notes.

Isolona pleurocarpa is distinguished by the combination of these characters: young leaves glabrous, leaf blade inserted on the side of the petiole and decurrent to narrowly cuneate at base, midrib proximally depressed above, corolla lobes narrowly ovate to ovate with a narrowed base and an acute apex, undulate-wavy on the margins when dried.

Specimens examined.

South Region: NE of Mt Elephant ca 20 km SE of Kribi, 2.8°N, 10.03°E, 10 February 1970, Bos J.J. 6298 (WAG); mountain chain Ngovoyang 42 km in forest from Bikiliki village situated between Bipindi and Lolodorf, 3.18°N, 10.53°E, 19 February 2012, Couvreur T.L.P. 402 (WAG,YA); Colline Nkolo Manga (20 km SE Kribi), 2.95°N, 9.916°E, 16 April 1968, Letouzey R. 9341 (P,WAG); Elephant Mont, 2.8°N, 10.01°E, 22 October 2001, van Andel T.R. 4177 (KRIBI,WAG,YA); Bipindi , 3.08°N, 10.41°E, 1895, Zenker G.A. 1716 (B,G,M,P,WAG); Bipindi , 3.08°N, 10.41°E, 01 January 1918, Zenker G.A. 22 (P,WAG); Mbiave, 3.21°N, 10.61°E, 01 January 1913, Zenker G.A. 267 (A,B,BR,C,G,M,MO,U,WAG); Bipindi , 3.08°N, 10.41°E, 01 April 1904, Zenker G.A. 3038 (B,COI,G,K,L,M,MO,P,S,WAG); Bipindi , 3.08°N, 10.41°E, 01 July 1904, Zenker G.A. 3217 (B,BR,G,K,L,M,S,WAG); Bipindi , 3.08°N, 10.41°E, 01 January 1908, Zenker G.A. 3433 (BR,COI,G,G,L,M,M,MO,P,S); Bipindi , 3.08°N, 10.41°E, 01 January 1908, Zenker G.A. 3540 (G,K,L,M,M,MO); Bipindi , 3.08°N, 10.41°E, 01 January 1909, Zenker G.A. 3921 (B,BR,COI,COI,G,L,M,M,MO,P,S); Bipindi , 3.08°N, 10.41°E, 01 January 1913, Zenker G.A. 4704 (BM,BR,G,K,L,M,P,S); Bipindi , 3.06°N, 10.38°E, 01 November 1919, Zenker G.A. 95 (BM). South-West Region : Southern Bakundu Forest 3 km from Kindongi Camp, 4.55°N, 9.416°E, 02 May 1972, Leeuwenberg A.J.M. 9784 (B,BR,C,H,K,LD,M,MO,P,WAG,YA); Korup National Park, 5.06°N, 8.783°E, 13 April 1978, Thomas D.W. 349 (K) .

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 38. Isolona hexaloba A trunk, note deeply furrowed B base of leaf blade, note raise midrib C flower, top view D flower, side view E fruiting branch. Isolona pleurocarpa F trunk G bade of leaf blade, notice decurrent base H flower, top view, fallen on ground I syncarpous fruit; fallen on ground A Sosef 2032, Gabon B-D Couvreur 561, Gabon E Texier 2347, Gabon F-I Couvreur 402, Ngovayang, Cameroon. Photos A-D, F-I Thomas L. P. Couvreur E Nicolas Texier, Tropicos. org, Missouri Botanical Garden.