Gilbertiodendron ebo Burgt & Mackinder

van der Burgt, X.M., Mackinder, B.A., Wieringa, J.J. et al. The Gilbertiodendron ogoouense species complex (Leguminosae: Caesalpinioideae), Central Africa. Kew Bulletin 70: 29. DOI https://doi.org/10.1007/s12225-015-9579-4

Type

Type: Cameroon, Littoral Region, Ebo Proposed National Park, path from Iboti village to Bekob Camp, at c. 7 km from Iboti and at 5.7 km from Bekob, 26 Nov. 2013, X. M. van der Burgt & E. Ngansop 1677 (holotype K! [K000745993, K000745994, K000745995], isotypes BR!, G!, MO!, P!, SCA!, WAG!, YA!).

Morphology General Habit

Tree, to c. 33 m tall

Morphology Trunk

Trunk to 69 cm diam. Twigs puberulent to glabrous, appressed reddish brown hairs to 0.2 mm long

Morphology Leaves Stipules

Stipules in pairs, free; reniform part persistent, a pair of stipules strongly inrolled towards each other; 10 – 40 × 8 – 18 × 5 – 15 mm, both sides sparsely puberulent to glabrous, hairs to 0.1 mm long; lanceolate part of stipule early caducous, c. 8 × 2 mm

Morphology Leaves

Leaves paripinnate, to 50 × 35 cm, on juvenile trees to 60 × 45 cm; petiole 6 – 20 mm long, 3 – 8 mm diam., sparsely puberulent, hairs to 0.3 mm long; leaf rachis (0 –) 9 – 34 cm long, on juvenile trees to 41 cm long, sparsely puberulent to glabrous, stipels absent, apex of rachis sometimes with a glandular-like structure; petiolules 5 – 11 mm long, sparsely puberulent to glabrous

Morphology Leaves Leaflets

Leaflets coriaceous, opposite, 1 – 6 pairs, upper pair obovate, other pairs elliptic, (7 –) 12 – 28 × (4 –) 5 – 10 cm, leaflets of juvenile trees to 33 × 13 cm; both sides smooth, dull to somewhat glossy and identical in colour, upper surface glabrous, lower surface sparsely puberulent to glabrous, hairs to 0.1 mm long; midrib glabrous above, prominent and sparsely puberulent below; 5 – 12 pairs of secondary veins; leaflet base obtuse to rounded, apex glandular, acute to acuminate, 1 – 15 mm long

Morphology General Glands

Glands 0 – 3 per leaflet, at the proximal margin 0 – 40 mm from the apex and at the distal margin 3 – 15 mm from the petiolule

Morphology Reproductive morphology Inflorescences

Inflorescence a congested, axillary or terminal cluster of 1 to several panicles, to 17 cm long, densely puberulous, hairs to 0.2 mm long, internodes to 30 mm long; lateral axes to 10 cm long, 6 – 8 flowers per cm

Morphology Reproductive morphology Flowers

Flowers: floral bract inserted at base of pedicel, caducous to persistent, broadly ovate, 4 × 4 mm, densely puberulous on both sides, upper part inside glabrous, dark brown hairs to 0.1 mm long; pedicel light green, 12 – 22 mm long, densely puberulous, dense light-coloured hairs to 0.1 mm long mixed with sparse dark brown hairs to 0.3 mm long; bracteoles 2, elliptic to lanceolate, light green to white outside, white inside, 12 – 16 × 7 – 8 mm, densely puberulous outside, dense light-coloured hairs to 0.1 mm long mixed with sparse dark brown hairs to 0.3 mm long; inside densely puberulous on upper part and near margin, centre glabrous; receptacle 3 mm high, 4 mm diam. at top, glabrous or with one or two patches of hairs outside, at adaxial and abaxial side; sepals 5, white, glabrous, sometimes a few hairs on margins, narrowly triangular, 10 – 13 × 2 – 3 mm, apex acute; petals 5, alternate to sepals, white, glabrous; adaxial petal claw 5 – 6 mm long, blade bilobed, 10 – 12 mm high × 18 – 24 mm wide; the other 4 petals 10 – 12 × 2 mm, apex acute, sometimes with a few hairs; stamens 3, inserted alternate to the 4 small petals; filaments white, glabrous, 22 – 26 mm long; anthers white to dark brown, glabrous, 4 mm long; 6 staminodes, filiform, to c. 4 mm long, inserted on a staminodal tube c. 1 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary light green, 5 × 2 × 0.5 mm, 7 – 8 ovules, margins densely hirsute, dark brown hairs to 0.8 mm long, sides glabrous; stipe 2 mm long; style white, 20 – 24 mm long, lower part sparsely hirsute, upper part glabrous; stigma capitate

Morphology Reproductive morphology Fruits

Fruits oblong-rectangular, brown, dull, glabrous, 2 – 7-seeded, 18 – 33 × 7 – 11 cm, valve 3 mm thick, beak 1 – 4 mm long, sutures not winged; 2.5 – 3.5 strong longitudinal ridges running from the base to the apex, parallel to and at 0.5 – 7 cm distance to the upper suture

Distribution

Gilbertiodendron ebo is endemic to Cameroon (Map 8).

Ecology

Gilbertiodendron ebo occurs in evergreen rain forest; at 200 – 800 m asl.

Conservation

Gilbertiodendron ebo is assessed here according to IUCN criteria as Endangered B1ab(i,iii,v) (Table 1).

Note

The type of Gilbertiodendron ebo, Burgt 1677, was collected from the tree from which Wieringa and Mackinder collected pods 6 years earlier (Wieringa 5923). The collection Burgt 1663 was collected from the tree beneath which Wieringa and Mackinder collected a sapling 6 years earlier (Wieringa 5922). These two trees are standing at 465 m distance to each other. They were revisited towards the end of November, because the only existing flowering collection was made 22 November 1963 (W. J. J. O. de Wilde 1306). Both trees were indeed flowering at the end of November 2013.

The species epithet of Gilbertiodendron ebo refers to the Ebo Forest in Cameroon, where the type specimen was collected. The Ebo Forest is proposed to become a national park, because of its abundance in primate species and plant species.

Gilbertiodendron ebo is related to G. minkebense. The reniform stipules (Fig. 9) are up to 40 × 18 × 15 mm and a pair of stipules is strongly inrolled towards each other (in G. minkebense the reniform stipules are usually flat and up to 20 × 12 mm, but sometimes to 32 × 22 × 10 mm with a pair of stipules strongly inrolled towards each other). Both sides of the leaflet of G. ebo are identical in colour (in G. minkebense the lower surface of dried leaflets is usually somewhat darker), the leaflet is not oblique (clearly oblique in G. minkebense), G. ebo has a leaflet midrib more prominent below (the midrib is more prominent above in G. minkebense). and the petiolule is 5 – 11 mm long (2 – 5 mm long in G. minkebense). The bracteoles are 12 – 16 mm long (instead of 7 – 11 mm long) and the number of ovules is 7 – 8 (instead of 3 – 4). The dimensions of the fruits of G. ebo are 18 – 33 × 7 – 11 cm, with 2 – 7 seeds (in G. minkebense the dimensions of the fruits are 10 – 15 × 4 – 5 cm, with 1 – 4 seeds).