Monanthotaxis submontana 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 : 200-202

68. Monanthotaxis submontana P.H.Hoekstra , sp. nov. — Fig. 30 ; Map 42

Monanthotaxis submontana belongs to the group of Monanthotaxis species with cauliflorous, unisexual flowers, but differs from all these species in the presence of stamens and/or staminodes (1–14) in pistillate and rarely in bisexual flowers. Furthermore, it is distinguished from most cauliflorous species by the combination of having oblong-elliptic leaves with a cuneate leaf base and inflorescences with a sympodial rachis up to 7 cm long, pedicels ranging from 7–55 mm long and flowers with 65–85 carpels. — Type: R. G. Letouzey 14476 (holo WAG0053953 ; iso MO 2 sheets, P01982361 ), Cameroon, Littoral, Nlonako , 5 km SEE of Nkongsamba, 1600 m, 17 Mar. 1976. Paratypes : M. R. Cheek et al. 9067 ( K, KUPE not seen, WAG, YA), Cameroon, South-West Region, Mount Kupe, Kodmin , ridge on S side of LOH mt, 1650 m, 23 Jan. 1998 ; M. R. Cheek et al. 9202 ( K, KUPE not seen, WAG, YA), Cameroon, South-West Region, Mount Kupe Division, Kodmin to Nzeembeng , c. 1 km past junction for Ngomin and crossing of Ndip river , 1150 m, 14 Feb. 1998 ; C. Doumenge 554 ( MO, P), Cameroon, South-West Region, forested slope in the Bakossi Mountains 1–8 km NNE of Menyum village, 1000 m, 22 May 1987 ; M. Etuge et al. 4122 ( K, WAG, YA), Cameroon, South-West Region, Nzimbeng road, 1300 m, 4 Feb. 1998 ; M. Etuge et al. 4442 ( K, KUPE not seen, WAG, YA), Cameroon, South-West Region, Kupe- Muanenguba division, Muahumzum, Kodmin road towards Mahusom , 1400 m, 12 Nov.1998 ; D. W. Thomas & Macleod 5274 ( MO, P, YA), Cameroon, South-West Region, forested hillsides in the Bakossi Mountains, west of Bangem , 800 m, 3 Jan. 1986 .

Etymology. Named submontana as this species is confined to the submontane forests of Cameroon.

Liana, 6–10 m long, c. 5 cm diam; young branches dark brown, covered with appressed to slightly erect, yellowish hairs, 0.1–0.2 mm long, becoming glabrous; old branches dark brown spotted green in vivo. Leaves: petiole 6–10 mm long, 0.7– 0.8 mm diam, grooved, indument as on branches; lamina narrowly oblong-elliptic to oblong-elliptic, 7.2–14.1 by 2.1–3.5 cm, 2.3–4.5 times longer than wide, chartaceous, not punctate, glaucous below, above densely covered with appressed, white to yellow hairs 0.2–0.3 mm long, primary vein more densely covered with persistent hairs, becoming glabrous, below covered with appressed,white hairs 0.2–0.3 mm long, primary vein covered with more persistent hairs, base cuneate, with thickened black margin, apex acute to acuminate, acumen to 15 mm long, secondary veins 11–18 per side, straight to curving upwards, tertiary venation percurrent. Inflorescences cauliflorous, composed of condensed many-flowered panicles; sympodial rachis to 7 cm long, densely covered with appressed to erect, reddish brown hairs 0.1–0.3 mm long; pedicels 7–55 mm long, 0.8–0.9 mm diam, fruiting pedicels 1.4–1.8 mm diam, densely covered with reddish brown hairs; lower bracts ovate, 1.3–2.2 by c. 0.8 mm, indument as on rachis; upper bracts in lower part of the pedicel, shape and indument as lower bracts;

b

flower buds ovoid to globose. Flowers bisexual or unisexual; sepals broadly ovate, 1.5–1.8 by 1.5–1.8 mm, densely covered with appressed hairs, persistent in fruit; receptacle c. 2.2 mm diam, convex to globose; petals dark brown to golden green on the outside, yellowish at the inside, 6, in two whorls, outer petals broadly ovate, 3.6–5 by 3.6–5.7 mm, outside densely covered with appressed, reddish brown, short hairs, inside covered with yellowish hairs c. 0.05 mm long, inner petals sometimes strongly reduced to absent, broadly elliptic, 0.4–1.3 by 0.3–1.1 mm, outside and inside covered with yellowish hairs c. 0.05 mm long; stamens 0–2(–4), in one whorl, free, often only 1 or 2 present near the inner petals and the others reduced to staminodes, oblong to slightly clavate, c. 1 mm long, filaments c. 0.6 mm long, hairy, thecae extrorse to latrorse, on top of stamen hiding connective, staminodes 0 –14 from very small to almost identical to the stamens;carpels 65–85, ellipsoid,0.8–0.9 by 0.4–0.5 mm, densely hairy, ovules 3–5, lateral, stigma globose, c. 0.1 mm diam, glabrous. Monocarps up to 18, medium green, moniliform, each part ellipsoid, 23–45 by 7–9 mm, smooth to slightly verrucose, covered with appressed, reddish brown, short hairs, apex apiculate, apiculum to 2 mm long, stipes 7–14 mm long, slightly grooved. Seeds 1–4, ellipsoid, 13–14 by 6–8 mm, tawny brown, ends rounded to apiculate, raphe slightly visible as a longitudinal furrow from base to apex.

Distribution — Cameroon (Littoral, South-West Region).

Habitat & Ecology — In submontane forest, montane forest and swamp forest. Altitude: 800–1650 m. Flowering: January, March; fruiting: January, February, May, November.

Preliminary IUCN conservation status — Endangered (EN): B2ab(iii). EOO: 173 km 2, AOO: 20 km 2. This species is known from 7 collections from a very small area of which the largest part is under threat by habitat destruction and by degradation.

Notes — 1. It is unclear if the stamens in the flowers of M. submontana really are fertile. In most flowers there are several staminodes present, which vary from hardly developed to almost stamen-like with thecae. It is unclear if those biggest stamens contain pollen or not and material in more advanced stages of flowering are needed to assess this.

2. On the sheets of Letouzey 14476 is written ‘only pistillate flowers apparently’. Letouzey probably overlooked the small stamens and staminodes as they are only visible when the inner petals are bend backwards.

Figures

Map 42 Distribution of Monanthotaxis submontana P.H.Hoekstra (■) and M. vulcanica P.H.Hoekstra (●).

Fig. 30 Monanthotaxis submontana P.H.Hoekstra. a. Habit; b. inflorescence; c. flower bud; d. flower bud with one outer petal removed; e. inner petal, inner and outside view; f. carpel; g. stamen, front and side view; h. fruiting inflorescence (all: Letouzey 14476). — Drawing by E. Winkel.