Isolona pilosa Diels, Bot. Jahrb. Syst. 41: 328, 1908

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 : 145-147

Isolona pilosa Diels, Bot. Jahrb. Syst. 41: 328, 1908

Fig. 39 ; Map 5E

= Isolona theobromina Exell, J. Bot. 64 (Suppl. 1): 10, 1926. Type. Angola. Cabinda, Pango Munga, Gossweiler J. 6112, 7 Jan 1916: holotype: BM[BM000889332]; isotypes: COI[COI00077211]; LISJC n.v.; LISC[LISC000094, LISC000095, LISC000096].

Type.

Democratic Republic of the Congo. Kasai Oriental; Lualaba, Ledermann C. 11, Mar 1906: holotype: B[B 10 0154216]; isotype: K n.v .

Description.

Tree, 13 m tall, d.b.h. up to 50 cm; stilt roots or buttresses absent, trunk not fluted. Indumentum of simple hairs; old leafless branches glabrous, young foliate branches densely pubescent. Leaves: petiole 3-12 mm long, 3-4 mm in diameter, densely pubescent, grooved, blade inserted on the side of the petiole; blade 19-27 cm long, 6-10 cm wide, obovate, apex acuminate, acumen 1-2 cm long, base rounded to cordate, papyraceous, below densely pubescent when young, densely pubescent when old, above sparsely pubescent to glabrous when young, sparsely pubescent to glabrous when old, concolorous; midrib raised above, above sparsely pubescent when young, sparsely pubescent when old, below densely pubescent when young, densely pubescent when old; secondary veins 15 to 20 pairs, glabrous below; tertiary venation reticulate. Individuals bisexual; inflorescences ramiflorous on old branches, axillary. Flowers with 9 perianth parts in 2 whorls, 1 to 2 per inflorescence; pedicel 2-4 mm long, 1-2 mm in diameter, densely pubescent; in fruit 2-8 mm long, 2-3 mm in diameter, pubescent; bracts 2 to 4, all basal, 2-4 mm long, 1-2 mm wide; sepals 3, valvate, free, 2-5 mm long, 2-4 mm wide, ovate, apex acuminate, base truncate, densely pubescent outside, glabrous inside, margins flat; petals basally fused, tube 5-10 mm long, inner and outer whorl not differentiated, equal; lobes 8-13 mm long, 3-5 mm wide, elliptic, apex acute, yellow, margins flat, densely pubescent outside, pubescent with base glabrous inside, curving inwards over the receptacle; stamens numerous, in 3 to 4 rows, 2 mm long, broad; connective discoid, glabrous; staminodes absent; carpels fused into a single structure, 2 mm long, stigma bilobed, glabrous. Fruit syncarpous, sessile, 30-60 mm long, 20-40 mm in diameter, ellipsoid, apex cuspidate, sparsely pubescent, longitudinally ribbed, color unknown; seeds not counted, 13-15 mm long, 6-8 mm in diameter, flattened ellipsoid; aril absent.

Distribution.

A central African species with a disjunct distribution, from Cameroon to Gabon and the Republic of Congo, also present in the Democratic Republic of Congo; in Cameroon known from the extreme East region.

Habitat.

A rare species in Cameroon; in lowland rain forests or swampy areas. Altitude 100-450 m a.s.l.

Local and common names known in Cameroon.

None recorded.

IUCN conservation status.

Vulnerable B2ab(iii) ( Cosiaux et al. 2019u).

Uses in Cameroon.

None reported.

Notes.

Isolona pilosa is the most pubescent species of the genus. It is distinguishable by its densely pubescent leaf midrib on the upper side (even in older leaves), as well as its short and densely hairy flowering pedicels. The corolla lobes are densely hairy on the outside and near the margins on the inside; the inner part of the tube is glabrous, which distinguishes it from I. congolona which is pubescent on the inner surface of the tube but glabrous on the outside.

Several specimens collected by Harris DJ are reported from The Lobéké National Park in East Cameroon, but we were not able to see them and verify their identification (e.g. 6408, 6538, 6627).

Specimens examined.

East Region: Region near Station Molundu Dscha (Ngoko) Nginda 21 km north Molundu, 2.2°N, 15.2°E, 07 January 1911, Mildbraed G.W.J. 4193 (HBG) .

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 39. Isolona letestui (not in Cameroon) A flowering branch B opened flower showing androecium and stigma C carpel (left) and transversal section of carpel (right) D stamens of innermost row (2 top) and stamen of outermost row (bottom). Isolona pilosa E flowering branch F opened flower showing androecium and stigma G stamen of outermost row (left) and innermost row (right) A-D from Le Testu 1252; E from Le Testu 8740 F, G from Le Testu 8602. Drawings by Helene Lamourdedieu, Publications Scientifiques du Museum national d'Histoire naturelle, Paris; modified from Le Thomas (1969 b, pl. 65, p. 351).