Monanthotaxis congolana (Boutique) P.H.Hoekstra

Hoekstra, P. H., Wieringa, J. J., Maas, P. J. M. & Chatrou, L. W., 2021, Revision of the African species of Monanthotaxis (Annonaceae), Blumea 66 (2), pp. 107-221 : 144-145

17. Monanthotaxis congolana (Boutique) P.H.Hoekstra — Map 11

Monanthotaxis congolana (Boutique) P.H.Hoekstra in Guo et al. (2017) 14. — Gilbertiella congolana Boutique (1951b) 124. — Lectotype (designated here): R.G.A. Germain 17 (lecto BR (BR000008799586); isolecto B100153067,BR000008799913,K000198957,NY00025920,P00046763), Democratic Republic of the Congo, Orientale, Yangambi, rive gauche, Litulombo, 470 m, 8 Dec. 1939.

Liana; young branches yellowish orange to greenish, sparsely covered with appressed, yellowish hairs 0.1–0.2 mm long, soon becoming glabrous; old branches reddish brown. Leaves: petiole 5–8 mm long, 0.7–0.8 mm diam, grooved, indument as on branches; lamina oblong-elliptic to ovate or narrowly so, 6.5–12.5 by 2.6–5.2 cm, 2.4–2.8 times longer than wide, chartaceous to subcoriaceous, punctate, but not well visible in older leaves, young leaves below sparsely covered with appressed hairs c. 0.1 mm long, soon becoming glabrous, base cuneate to broadly cuneate, with thickened margin, apex acute to acuminate, acumen to 15 mm long, secondary veins 6–8 per side, oblique, curving upwards, tertiary venation reticulate, raised above. Inflorescences axillary or terminal, solitary, flowers in fascicles or in to 2 cm long lax panicle-like, up to 4-flowered rhipidia; sympodial rachis absent or 1–5 mm long, sparsely covered with appressed, yellowish hairs; flowering and fruiting pedicels 6–14 mm long, 0.4–0.7 mm diam, covered with appressed, short hairs; lower bracts absent or ovate, 0.5–0.7 by c. 0.4 mm, densely covered with appressed, yellow hairs; upper bract ovate, 0.3–0.8 by 0.2–0.3 mm, indument as on lower bract, placed halfway up the pedicel; flower buds globose to slightly ellipsoid. Flowers bisexual; sepals free, shallowly triangular, 0.2–0.5 by 0.5–0.7 mm, apex acute, covered with appressed, yellowish, short hairs; receptacle 1.3–1.8 mm diam, flat; petals yellow-green, 6, in one whorl, outer petals overtopping inner petals in bud, elliptic to ovate, with inward hook at top, 1.8–2.7 by 1.1–2.1 mm, outside papillate to sparsely covered with appressed, short hairs, inside papillate, often denser so at apex and base; stamens 12, in one whorl, free, alternating with and opposite the petals, obconical to slightly clavate, wider than thick, length 0.8–1.1 mm, width 0.3–0.4 mm, radial width 0.3–0.4 mm, densely papillate, filaments c. 0.05 mm long, thecae 2, latrorse or extrorse, connective truncate, circular seen from above, densely papillate, staminodes absent; carpels 7 or 8, ellipsoid, 0.8–1.2 by 0.4–0.6 mm, densely covered with reddish brown hairs, ovules 6, lateral, stigma subsessile, globose, <0.1 mm long, grooved, glabrous. Monocarps up to 4, orange-red, cylindric, 90–110 by 6–8 mm, slightly constricted between the seeds, glabrous, apex apiculate, apiculum c. 1 mm long, stipes 9–12 mm long. Seeds 1–3, cylindric, 24–26 by c. 5 mm, ochre-brown, apex apiculate, apiculum c. 1 mm long, raphe not visible.

Distribution — Democratic Republic of the Congo (Bandundu, Equateur, Maniema, Orientale).

Habitat & Ecology — In periodically inundated primary forest and terra firme forest. Altitude: c. 470 m. Flowering: February, May, June, September, December; fruiting: February, December.

Vernacular name — Democratic Republic of the Congo: Nginko e Likebe (Turumbu name) (R.G.A. Germain 17).

Preliminary IUCN conservation status — Endangered (EN): B2ab(iii). EOO: 332 197 km 2, AOO: 28 km 2. This species is known from 5 localities, including one nature reserve. However, it has not been collected since 1959 and its present existence is doubtful.

Note — Monanthotaxis congolana and M. latistamina are the only two species of Monanthotaxis with densely papillate petals and stamens. Flowers of M. congolana have 12 linear stamens (vs 6 oblong stamens in M. latistamina ), which are circular in cross-section (vs ellipsoid in cross-section).

Figures

Map 11 Distribution of Monanthotaxis confusa P.H.Hoekstra (●, O means uncertain det) and M. congolana (Boutique) P.H.Hoekstra (■).