Monanthotaxis ursus P.H.Hoekstra, 2021

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 : 206-207

73. Monanthotaxis ursus P.H.Hoekstra , sp. nov. — Fig. 32 ; Map 41

Monanthotaxis ursus , together with M. gracilis and M. quasilanceolata , are the only species of Monanthotaxis with a hairy stigma. Monanthotaxis ursus differs from M. quasilanceolata in the much shorter pedicels,shorter hairs on the young branches and the truncate connective. From M. gracilis it differs in having a denser indument of erect, 0.3–0.4 mm long hairs on the lower side of the leaves,while M.gracilis has almost glabrous leaves except for a few scattered hairs on the primary vein. Furthermore, M. ursus has broader leaves, 5.3–9 cm wide, and short flowering pedicels,to 7 mm long, while M. gracilis has leaves 1.4–5.7 cm wide and the flowers pending on 15–45 mm long pedicels. — Type: L. Aké Assi 17225 (holotype consisting of 2 sheets: G), Ivory Coast, Guiglo, route de Tabou, forêt près Sièblohoula, 29 Dec. 1985.

Etymology. This species is named ‘ursus’ after the genus name for bears, as this species is much more hairier than the related M. gracilis . Ursus is here used as a noun.

Growth form unknown ; young branches densely covered with erect to ascending, reddish brown hairs 0.1–0.2 mm long, becoming glabrous; old branches dark brown to reddish brown. Leaves: petiole 5–11 mm long, 1.7–2.2 mm diam, slightly grooved, indument as on branches; lamina obovate, 11.1–17 by 5.3–9 cm, 1.9–2.1 times longer than wide, chartaceous, not punctate, above sparsely covered with ascending to erect, white hairs 0.3–0.4 mm long, primary vein densely covered with erect, yellowish hairs, below densely covered with ascending, yellow hairs 0.3–0.4 mm long, base subcordate, with thickened black margin, apex acute to acuminate, acumen 5–10 mm long, secondary veins 12–14 per side, straight, halfway slightly curving upwards, tertiary venation percurrent. Inflorescences leaf-opposed or terminal, composed of 2- or 3-flowered rhipidia; sympodial rachis 2–3 mm long, densely covered with ascending, reddish brown hairs; pedicels 5–7 mm long, 1–1.2 mm diam, fruiting pedicels c. 24 mm long, c. 1.3 mm diam, densely covered with ascending, reddish brown hairs; lower bract absent or broadly ovate, c. 0.5 by 0.5 mm, indument as on pedicel; upper bract halfway up the pedicel, ovate to lanceolate 3.5–4.5 by c. 0.8 mm, densely covered with ascending hairs; flower buds ovoid to deltoid. Flowers bisexual; sepals free, ovate, 3.5–4 by 1.6–2.1 mm, apex acute, densely covered with appressed, whitish hairs, persistent in fruit; receptacle c. 2 mm diam, convex; petals colour in vivo unknown, 6, in two whorls, outer petals ovate, 8.5–9 by 5–6 mm, outside and inside covered with yellowish brown hairs, inner petals elliptic, 4–4.5 by 2.4–2.7 mm, outside densely covered with yellow-brown hairs, inside glabrous; stamens c. 130, in four or five whorls, free, linear-oblong, 0.7–0.8 mm long, filaments c. 0.1 mm long, thecae extrorse to latrorse, connective truncate, globose, prolongation hiding the thecae, glabrous, staminodes absent; carpels c. 45, subcylindric, c. 1.7 by 0.2–0.3 mm, densely hairy, ovules c. 5, lateral, stigma globose to ellipsoid, c. 0.4 mm long, hairy. Monocarps up to 26, only young ones seen, colour in vivo unknown, 1–5-seeded, c. 40 by 4 mm, slightly constricted between the seeds, densely covered with ascending hairs, apex apiculate, stipes 2.5–4 mm long. Seeds 1–5, ripe seeds unknown.

Distribution — Ivory Coast (Guiglo).

Habitat & Ecology — In forest. Flowering: December; young fruits: December.

Preliminary IUCN conservation status — Critically Endangered ( CR): B2 ab(iii). AOO: 4 km 2. Only known from the type collection in an unprotected area. Near the type location in both Ivory Coast and Liberia are nature reserves. It should be searched for in those areas, but meanwhile as it has not been collected in more than 30 years the status of critically endangered is proposed .

Figures

Map 41 Distribution of Monanthotaxis stenosepala (Engl. & Diels) Verdc. (●) and M. ursus P.H.Hoekstra (■).

Fig. 32 Monanthotaxis ursus P.H.Hoekstra. a. Flowering branch; b. flower with petals and sepals removed; c. carpel; d. stamen, side and front view; e. monocarp (all: Aké Assi 17225, G). — Drawing by E. Winkel.