Garcinia gabonensis Sosef & Dauby, 2012

Sosef, Marc S. M. & Dauby, Gilles, 2012, Contribution to the taxonomy of Garcinia (Clusiaceae) in Africa, including two new species from Gabon and a key to the Lower Guinean species, PhytoKeys 17, pp. 41-62 : 47-48

Garcinia gabonensis Sosef & Dauby Fig. 2

Diagnosis.

Similar to Garcinia kola , but leaves with lateral veins towards the margin clearly connected in distinct loops and united into an intramarginal vein that runs at (1-)2-3 mm from the margin, free stamens and a well-developed, longitudinally ribbed pistillode.

Type.

GABON: Ngounié, c. 36 km Mouila to Yeno, 1°45'S, 11°20'E, 19-9-1986, Breteler 7782 (holotype WAG!; isotype BR!, K!, LBV!, MO!, P!, PRE).

Description.

Dioecious shrub or small tree, up to 4 m high; latex transparent to greenish; branches circular in cross section, fissured, often reddish when dry; twigs flattened on cross section, smooth. Leaves opposite; petiole (4-)5-10(-12) mm, smooth, slightly canaliculated above, with indistinct foveola of about 1 mm long; blade generally oblanceolate, sometimes elliptic or rarely ovate, (7-)8-15(-16) × (2-)2.5-5(-6) cm, pointed at base, caudate-acuminate at apex, coriaceous to papery, glabrous; midrib prominent below, canaliculate above, lateral veins 7-13 pairs, visible on both surfaces, towards the margin clearly connected in distinct loops and united into an intramarginal vein that runs at (1-)2-3 mm from the margin, tertiary veins laxly reticulate, indistinct; resin ducts normally indistinct except in young leaves, subparallel to the midrib. Inflorescence axillary, of few-flowered fascicles; bracts many, small (<1 mm long). Flower 4-merous, unisexual; pedicel slender, 2(-3) mm; sepals obovate, two external ones about 2 mm long, two internal ones about 4 mm long, greenish to yellowish; petals obovate, about 4 mm long, yellowish or greenish to white. Male flower: stamens 8-14, free, inserted in a ring around the pistillode, filament broadened and flat, white, anthers ellipsoid, strongly curved; pistillode broadly triangular-obovoid, longitudinally ribbed, stylode simple and slender, 1-2 mm long. Female flower:disc annular, flattened and pressed against the ovary; ovary globose, about 3 mm in diameter; stigma peltate, lobed, 2 mm wide. Fruit ovoid to subglobose, 5-11 mm in diameter, greenish, smooth, with persistent sepals at base.

Distribution.

Endemic to southern and central Gabon, in the provinces of Moyen-Ogooué, Ngounié and Ogooué-Maritime (see Figure 3b ).

Habitat and ecology.

Primary or late secondary terra firme rain forest, along rivers or on ridges; at ca. 150-850 m altitude. Flowering in September to November, fruiting in September, November, December and February.

Conservation status.

Currently, Garcinia gabonensis is known from eleven collections and nine locations. Estimates of the extent of occurrence and the area of occupancy are respectively ca. 16 000 km2 and 109 km2. Since nine of the eleven collections are within logging concessions or along main roads, we consider that continuing decline in the extent of occurrence, area of occupancy, quality of habitat and number of sub-populations has occurred or will occur in the near future. We therefore assign a preliminary status of Vulnerable (VU B2ab(i,ii,iii,iv)).

Notes.

For now, it remains unclear as to which section this species belongs. Most striking feature are the free stamens. According to the elaborate work of Jones (1980), this is characteristic for only two sections: sect. Teracentrum Pierre and sect. Rheedia sensu Jones. Species belonging to the first, however, have their stamens inserted across a central mass and lack a pistillode. Those belonging to the second are known to occur, until now, only in Central and South America and on Madagascar …. Morphologically though, Garcinia gabonensis seems very similar to other species in sect. Rheedia , and this might be the first continental African representative of that section. A molecular study to further investigate this will be performed soon.

Additional specimens examined

(all from Gabon). SE of Sindara, km 12 from Camp Chantier Waka to Ngounié River, 1°14'S, 10°51'E (DMS), 26/9/1985 (fl.), Leeuwenberg & Persoon 13683(BR, K, WAG). Moukabo, about 37 km E of Mouila, on the road to Yeno, 1°40'S, 11°20'E (DMS), 27/11/1984 (fl.), Arends et al. 484 (WAG). about 40 km E of Mouila, on the road to Yeno, 1°40'S, 11°20'E (DMS), 28/11/1984 (fr.), Arends et al. 510(BR, LBV, WAG). Massif du Chaillu, old secondary forest partly primary, near Mouyanama, about 27 km. E. of Mimongo, 1°39'S, 11°46'E (DMS), 25/11/1983 (fl.), Louis et al. 854 (K, WAG). Fougamou, 7 km on forestry road following Bendolo river, 1°12.1'S, 10°32.2'E (DDM), 26/10/1994 (fl.), Wieringa et al. 2916 (LBV, WAG). 10 km on the road Ikobey to Bakongue, Eghaba Mountain, 1°2.0'S, 10°2.6'E (DDM), 28/11/2001 (fl., fr.), Wieringa et al. 4473 (WAG). 5-15 km NNW of Ndjolé, 0°5'S, 10°45'N (DMS), 13/11/1991 (fl.), Breteler 10445 (LBV, WAG). 13 km on the road Eteké to Ovala, Nyongué, 1°26.1'S, 11°26.1'E (DDM), 8/11/1994 (fl.), Wieringa et al. 3096(WAG). 60 km on the road Mouila to Yeno, 1°41.85'S, 11°23.96'E (DDM), 3/12/2001 (fr.), Wieringa et al. 4546 (LBV, WAG). Doudou mountains, about 60 km along exploitation track in WNW direction from Doussala, 2°12'S, 10°11'E (DMS), 27/11/1986 (fl.), Wilde J.J. de et al. 8984 (K, LBV, WAG). Massif du Chaillu, near Guédévé village about 40 km N of Lébamba, 1°55'S, 11°25'E (DMS), 30/11/1983 (fr.), Louis et al. 1056 (K, WAG). Est du Parc National de Waka, à environ 5 km au Sud de la rivière Mayi, 1°23'S, 11°3'E (DMS), 21/2/ 2008 (fr.), Dauby et al. 735 (LBV, MO, BRLU).

Figures

Figure 2. Garcinia gabonensis: A Flowering twig B, C Leaves, showing the variation D Male flower E Idem, open and three petals removed F Androecium G Stamen H Pistillode I Female flower J Gynoecium and disk K Fruit. (A, D-H: Leeuwenberg & Persoon 13683; B, K: Arends et al. 510; C, I, J: Wieringa et al. 4546). Drawing by Hans de Vries, NCB Naturalis (section NHN) ©.

Figure 3. Distribution of the two new species endemic to Gabon: (a) Garcinia obliqua, (b) Garcinia gabonensis.