Angraecum oliveirae Stévart & Jecmenica, Phytotaxa 323: 153 (2017).
Homotypic Names:
Conchograecum oliveirae (Stévart & Jecmenica) Szlach., Grochocka, Oledrz. & Mytnik, Richardiana, N.S. 2: 93 (2018).
Description:
Creeping to ascendant, monopodial epiphytic herbs, stem reaching 6 cm. Leaves distichous, dimorphic, young leaves towards the apex of the stem, elliptic-oblong, 2.5-4.2 x 1.2-1.8 cm, lowermost leaves 8.0-10.8 x 2.8-3.0 cm, narrowly elliptic to oblong, unequally bilobed and rounded at the apex; larger lobe round 2 mm, smaller lobe ends obtusely; margins entire; 7 nerves on the leaf blade with prominent midvein; stomata visible. Internodal distance 17-20 mm. Inflorescence indeterminate, bearing up to four flowers in consecutive seasons; peduncle 1-3 cm long. Bracts narrow, 3 mm long. Flowers resupinate, yellow (collectors’ notes), tepals convolute, dorsal sepal slightly undulate. Ovary/pedicel 7.5-12.5 mm long, slightly curved. Dorsal sepal 13.0-18.0 x 4.0-5.8 mm, elliptic, acute, slightly undulate from the sideways with entire margins. Lateral sepals slightly narrower 13.5-18.0 x 3.5-5.0 mm, obliquely elliptic or with falcate acute apex, margins entire. Petals 12.0-15.5 x 4.0-5.5 mm, identical to lateral sepals. Lip 10-15 x 5-7 mm, concave, narrowly ovate to trullate when flattened, widest at first third where entire margins can appear slightly thickened, acute apex, possesses callus in the form of a longitudinal ridge; spur 13.5-15.0 mm long, cylindrical, horizontally straight or slightly rising, apically elliptically swollen for at least half of its length. Column 3 x 2 mm, rostellum bifid, with protruding tips that close the sinus between the two lobes of rostellum. Anther cap 1.5 x 2.0 mm, round with a flat tip. Two stipites and two viscidia both elliptic-ligulate, loosely connected only at the tip. Pollinia two, 1 mm, obovoid. Capsule not seen.
Etymology:
The species is named for our collaborator and colleague Faustino de Oliveira from Sao Tomé, former Curator at STPH, who collected and cultivated specimens of this species in the shadehouse of Bom Successo.
Habitat:
Angraecum oliveirae is known from three localities in Sao Tomé; the holotype comes from the dense forest of the descending towards the valley of the Io Grande River, whereas the two other specimens were found in secondary forests in an old plantation in Bombaim and Formoso Grande.
Phenology:
In cultivation flowering June-July.
Notes:
Angraecum oliveirae is similar to A. cribbianum but differs in its shorter stem (6 vs. 10-20 cm), inflorescence length (1.0-2.5 vs. 3.5-5.0 cm) and pedicel/ovary length (7.5-12.5 vs. 14.0-17.5 mm), slightly longer, but wider sepals and petals, lip shape (narrowly ovate-lanceolate vs. elliptic-oblong with constricted apex) and spur shape and length (straight; 13.5-15.0 mm vs. curved; 10.0-11.0 mm).
Distribution:
São Tomé
References:
Taxonomy of Atlantic Central African orchids, 6: three new species of Angraecum sect. Afrangraecum (Orchidaceae, Angraecinae) from Gabon and Sao Tomé Phytotaxa 323 (2): 143–158,2017 by Vincent Droissart and Tariq Stévart
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