Garcinia obliqua 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 : 45-46

Garcinia obliqua Sosef & Dauby Fig. 1

Diagnosis.

Similar to Garcinia smeathmannii but leaves with 6-9 pairs of lateral veins, tertiary venation only slightly distinct above, petiole almost smooth, and fruits asymmetric with a coriaceous and ribbed skin.

Type.

GABON: Ogooué-Ivindo, near Djidji, 5-10 km West of Koumémayong, 0°15'N, 11°50'E (DMS), 25-4-1988, Breteler 8993 (holotype WAG!; isotype BR!, K!, LBV!, MO!, P!).

Description.

Dioecious tree; bole up to 35 cm dbh; twigs round to slightly angular in cross section; latex transparent or yellow. Leaves opposite; petiole (0.8-)1-1.5(-2) cm long, smooth or slightly transversely wrinkled, with a distinct foveola of up to 3 mm long; blade elliptic to lanceolate, (8-)9-17(-18) × 2.5-6 cm, attenuate at base, acuminate at apex, glabrous; lateral veins 6-9 pairs, distinct below, slightly distinct above, disappearing towards the margin; tertiary venation visible to distinct below, slightly distinct above; resin canals visible on the lower surface, black and subparallel to the midrib. Inflorescence axillary, with fascicles of flowers on swellings in the axils of twigs. Flowers 4-merous, unisexual; pedicel 3-6 mm; external sepals about 2.5 mm long, internal ones about 3 mm, greenish; petals suborbicular, about 4 mm long. Male flower: staminal bundles tree-like, with 10-19 irregularly positioned stamens per bundle, filaments free at the apex, anthers small, subglobose; pistillode present. Female flower not observed. Fruit on a 12 mm long pedicel (only 1 fruit with pedicel observed), asymmetric, oblique, probably because of aborted ovules, circular to broadly ovate in cross section, 3-3.5 × 1.8-2 cm; e xocarp strongly furrowed and coriaceous and green with blue reflection in dry condition. Seed 1, obliquely ellipsoid, 2-3 × 1.5-2 cm, black.

Distribution.

Endemic to central Gabon, known only from the Ogooué-Ivindo and Ngounié provinces (see Figure 3a ).

Habitat and ecology.

Primary terra firme rainforest; at ca. 450-800 m altitude. Flowering in April, fruits observed in February.

Conservation status.

Garcinia obliqua is currently known from nine collections and six locations. Estimates of its extent of occurrence and area of occupancy are respectively ca. 9488 km2 and 80 km2. One collection (Dauby et al. 1650) corresponded to a dead individual along a forestry road and all locations are currently found within logging concessions. Hence, we assume the extent of occurrence, area of occupancy, quality of habitat and number of sub-populations will decrease in the near future. We therefore assign a preliminary status of Vulnerable (Vu B1ab(i,ii,iii,iv,v)+B2ab(i,ii,iii,iv,v)).

Notes.

The shape of the staminal bundles and the anthers, as well as the distinct foveola point to a relationship with Garcinia smeathmannii and Garcinia ovalifolia , both belonging to the section Rheediopsis Pierre (Jones, 1980). On the other hand, preliminary molecular data obtained by the second author suggest that Garcinia obliqua is not related to these species. Therefore, the results of an upcoming molecular study are awaited before a firm statement about the sectional position can be made.

Additional specimens examined

(all from Gabon). CFAD de Rimbunan Hijau, au Sud-Ouest du Parc National de la Lopé, 0.64°S, 11.16°E (DD), 2/2/2009 (fr.), Dauby et al. 1570 (LBV, MO, BRLU). CFAD de Rimbunan Hijau, au Sud-Ouest du Parc National de la Lopé, 0.7°S, 11.23°E (DD), 27/2/2009 (fr.), Dauby et al. 1643 (BRLU). CFAD de Rimbunan Hijau, au Sud-Ouest du Parc National de la Lopé, 0.7°S, 11.23°E (DD), 28/2/2009 (ster.), Dauby et al. 1650 (BRLU). near Djidji, 5-10 km W. of Koumémayong, 0°15'N, 11°50'E (DMS), 15/4/1988 (fl.), Breteler et al. 8738 (WAG). Est du Parc National de Waka, à plus ou moins 5 km au Sud de la rivière Mayi, 1.23°S, 11.28°E (DD), 4/6/2008 (ster.), Dauby et al. 677 (BRLU). Est du Parc National de Waka, à plus ou moins 5 km au Sud de la rivière Mayi, 1.23°S, 11.28°E (DD), 4/6/2008 (ster.), Dauby et al. 666 (BRLU). Bouvala hills, 1.62°S, 11.75°E (DD), 8/10/2007 (ster.), MBG transect (Leal et al.) 1105 (BRLU). Bouvala hills, 1.63°S, 11.78°E (DD), 12/10/2007 (ster.), MBG transect (Leal et al.) 1106 (BRLU). Village Eghuba, nord-ouest du Parc National de Waka, 1.03°S, 11.14°E (DD), 12/5/2008 (ster.), Ngombou Mamadou & Ndjombe 226 (LBV, MO).

Figures

Figure 1. Garcinia obliqua: A Flowering twig B Leaf from below C Idem, detail D Male flower E Idem, 1 sepal and 2 petals removed F Fruit. (A: Breteler et al. 8993 B, C, F: Dauby et al. 1570; D, E: Breteler et al. 8738). 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.