Monanthotaxis atewensis 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 : 127

3. Monanthotaxis atewensis P.H.Hoekstra — Fig. 4 ; Map 3

Monanthotaxis atewensis P.H.Hoekstra in P.H. Hoekstra et al. (2016) 76. — Type: J.B. Hall GC43672 (holo consisting of 2 sheets: WAG0019665 , WAG0019666 ;iso GC, K000040198 , MO), Ghana, Eastern Region, Atewa Range Forest Reserve , 2 June 1973.

Scandent shrub or liana, to 9 m long; young branches sparsely covered with erect, reddish brown hairs 0.3–0.5 mm long, becoming glabrous; old branches pale brown. Leaves: petiole 3–5 mm long, 1–1.2 mm diam, grooved, indument as on branches; lamina oblong-elliptic to obovate or slightly oblanceolate, 5.7–15.9 by 2.4–5.4 cm, 2–3.1 times longer than wide, chartaceous, not punctate, above greyish, glabrous except for a few short hairs near the base of the primary vein, below sparsely to densely covered with erect, reddish brown hairs 0.4–0.6 mm long, base rounded, truncate or subcordate, glands hardly visible, apex acute to acuminate, acumen to 15 mm long, secondary veins 8–14 per side, straight and halfway curving upwards, tertiary venation percurrent. Inflorescences leaf-opposed, composed of solitary flowers to 3-flowered rhipidia; sympodial rachis 2–4 mm long; pedicels c. 21 mm long, c. 0.7 mm diam, fruiting pedicels 20–37 mm long, 0.6–1.1 mm diam, covered with ascending to erect, yellowish, short hairs; lower bracts strongly reduced or absent; upper bract around the middle of the pedicel, broadly ovate, c. 1.7 by 1.4 mm, densely covered with appressed, short hairs. Flowers bisexual; sepals free, lanceolate, 10–12 by 2.6–2.7 mm, apex acute, densely covered with appressed, short hairs, persistent in fruit or falling off; receptacle c. 3 mm diam, flat; petals unknown; stamens unknown, scars in a single whorl; carpel number unknown, ellipsoid, c. 1.2 by 0.5 mm, densely hairy, ovules unknown, stigma elongate, c. 0.5 mm long, grooved, glabrous. Monocarps 1–9, green when young, ellipsoid to narrowly ellipsoid, 13–35 by 5 – 6 mm, slightly to strongly constricted between the seeds, slightly verrucose, sparsely covered with erect, short hairs, apex apiculate, apiculum to 2 mm long, stipes 4 – 6 mm long, slightly grooved. Seeds 1–5, ellipsoid, c. 9 by 6 mm, tawny brown, base and apex rounded, raphe visible from base to apex.

Distribution — Ghana (Eastern Region).

Habitat & Ecology — In forest, in thicket. Altitude: c. 750 m. Fruiting: May, June.

Preliminary IUCN conservation status — Critically Endangered (CR): B2ab(iii). AOO 4 km 2. This species is only known from the Atewa Range Forest Reserve and has not been collected in more than 40 years. Furthermore, the reserve is under threat of bauxite mining and logging ( Kusimi 2015, Ntiamoa-Baidu et al. 2000), even more so since in 2020 the actual exploration has started, and already a few percent of the upland forest was destroyed for exploration tracks (pers. observ. Wieringa).

Notes — 1. Monanthotaxis atewensis is easily distinguishable from all other Monanthotaxis species by the large, lanceolate sepals. This species is closely related to M. stenosepala from Sierra Leone and M. discrepantinervia from Tanzania based on sepals, which are as large as the petals. It differs from both species by the erect hairs on the leaves and branches. It differs from M. stenosepala in the larger sepals and the larger number of seeds per monocarp, while the sepals of M. discrepantinervia are ovate (vs lanceolate).

2. In Liberia there are two fruiting specimens (J­G Adam 26189 and FSC Stoop 331) which resemble M. atewensis , but the monocarps are more densely verrucose, the sympodial rachis is shorter and the pedicels are larger than the specimens from Ghana. Furthermore, no sepals are present to verify the identification and for now we refrain from assigning them to this species.

Figures

Map 3 Distribution of Monanthotaxis aquila P.H.Hoekstra (●) and M. atewensis P.H.Hoekstra (■).

Fig. 4 Monanthotaxis atewensis P.H.Hoekstra. a. Leaf; b. leaf detail; c. old flower; d. fruit (a–b, d: Hall & Lock GC43672; c: Hall & Enti GC36426). — Drawing by M. Spitteler, reproduced from Hawthorne & Jongkind (2006).