Mendoncia floribunda (Pierre) Benoist

Breteler, F. J. & Wieringa, J. J., 2018, A synopsis of Mendoncia (Acanthaceae) in continental Africa including the description of two new species from western Central Africa and a new subspecies from West Africa, Blumea 63 (2), pp. 109-119 : 113

3. Mendoncia floribunda (Pierre) Benoist — Fig. 2; Map 3

Mendoncia floribunda (Pierre) Benoist (1944) 143; Heine (1966) 68, in synonymy of M. lindaviana . — Lirayea floribunda Pierre (1896) 342. — Afromendoncia floribunda (Pierre) Burkill (1899) 6. — Monachochlamys floribunda (Pierre) S. Moore (1929) 226. — Type: Jolly 101­bis (holo P), Gabon, near Libreville, 15 Oct. 1891, see notes.

Cauliflorous liana, at least 10 m high climbing. Branchlets velutinous-pilose to hispidulous, mixed with some glandular hairs, the same indumentum except for the glandular hairs, present on petioles and midrib and main lateral nerves of the leaves beneath. Leaves ± opposite: petiole sharply bent in adult leaves, 12–19 mm long; lamina firmly papery to coriaceous, elliptic to obovate, 1.5–2 times as long as wide, 9–18 by 5.5–10 cm, rounded to cordate at base, acute to 0.5–1 cm acuminate at apex, brown-hairy on midrib and, to a lesser extent, on the 7–8 pairs of main lateral nerves above when young. Inflorescence pseudo-fasciculate on the main stem up to c. 2 m high, flowers on short rachises, up to at least 10 rachises present on each node, 1–3 flowers per season per rachis, the rachises bear scars of more flowers from previous seasons. Flowers glabrous. Pedicel 20–22 mm long, slightly thickened towards the apex, glabrous. Bracteoles concave, elliptic, 12–15 by 7–9 mm, acute to apiculate at apex, glabrous both sides, deciduous in fruit. Calyx cupular, 2–3 mm long, glabrous, margin entire to somewhat undulate to shallowly dentate. Corolla white, tubular, glabrous, outside, c. 2 cm long, lobes 4–5 mm long, apically reflexed with ± sessile glands inside; tube c. 15 mm long, at base slightly bulging over the calyx edge, with stalked glands inside below stamen attachment. Fertile stamens 4; filaments glabrous, 1–3 mm free from corolla tube; anthers 4–6 mm long, often with thecae unequal in length, apically with stalked glands and with papillose hairs at base. Staminode apically free from corolla tube, ± oblongoid, glabrous. Disc cupular, c. 2 mm long, glabrous. Pistil c. 20 mm long, glabrous; ovary 2–3 mm long, 1–2-locular, with 1–2 ovules per locule; style shallowly and slightly unequally bilobed apically. Fruit (immature) obovoid-ellipsoid, slightly laterally compressed, 14 by 10 by 5–6 mm, glabrous.

Habitat & Distribution — Tropical rain forest in Gabon. Altitude up to c. 300 m.

Additional specimen studied. GABON, Ngounié, Breteler et al. 14049 ( BR, BRLU, E, K, LBV, MO, WAG), between Yombi and Fougamou, eastern slope of Koumounabouali ridge, S1°20' E10°40', in disturbed primary forest, 22 Sept. 1997 .

Conservation status — Mendoncia floribunda has only been collected twice, resulting in an AOO of 8 km 2. The type was collected 125 years ago in present day Libreville and this subpopulation should be considered lost, resulting in a current AOO of 4 km 2. The other known locality does not have any protected status, while there is continuous logging in this area. We therefore assess this species as Critically Endangered ( CR, B2 a, b(ii, iii)) .

Note — Lirayea floribunda of Pierre was based on Jolly 101­ bis, a specimen consisting of a few inflorescences attached to a part of a stem and a single, separate leaf. The inflorescence is like that of M. lindaviana , but the hairy leaf is not, because M. lindaviana has glabrous leaves. Pierre (1896) did not want to describe this leaf as belonging to his Lirayea floribunda , because it was not attached to the flowering element of his type material. Flowering or fruiting herbarium material of the cauliflorous M. lindaviana for instance, is very rarely found attached to a leafy branch, because these elements are, in nature, usually separated by several meters. When only the flowering element of Jolly 101­bis is taken into account, it is understandable that Heine (1966) synonymised Pierre’s name under Mendoncia lindaviana . In his reasoning, however, Heine made a mistake in notifying that Zenker 965, to which Pierre’s type material was compared, is an isotype of Afromendoncia lindaviana . The latter is only based on Soyaux 156, Zenker 965 was not yet collected. The collection Breteler et al. 14049 shows that a cauliflorous Mendoncia like M. lindaviana but with hairy leaves does exist. Collecting of this specimen was carefully executed by climbing the supporting tree in order to assure that the leafy branchlets were collected from the same individual as the flowering elements. The hairy leaves have been compared with the single leaf of Jolly 101­bis with the inevitable conclusion that both collections belong to the same species: Mendoncia floribunda , distinct from M. lindaviana . The type specimen of Mendoncia floribunda in P does not show any corolla’s, although Pierre (1896) described them in his protologue and they are depicted in the accompanying illustration by Delpy. They may have been lost. The type material is numbered Jolly 101­bis and Delpy refers to it as such on the illustration. Pierre in his protologue of the basionym Lirayea floribunda , however, refers to it as Jolly 101.

Figures

Map 3 Distribution of Mendoncia floribunda (Pierre) Benoist.