Monanthotaxis pellegrinii Verdc.

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 : 187-189

59. Monanthotaxis pellegrinii Verdc. — Fig. 7h–m ; Map 35

Monanthotaxis pellegrinii Verdc. (1971b) 28, non M. letestui Pellegr. (1950) . — Popowia letestui Pellegr. (1949) 213. — Lectotype (designated by Le Thomas 1969: 226): G.M.P.C. Le Testu 9028 (lecto consisting of 3 sheets: P00362618, P00362621, P00362623; iso BM000553843, BR0000008823779, BR0000008823786, BR0000008823830), Gabon, Woleu-Ntem, region de Bitam, bords de la Kyé à Meyo, 12 Mar. 1933.

Scandent shrub or liana, to 3 m long; young branches densely covered with ascending, reddish brown hairs 0.1–0.3 mm long, becoming glabrous; old branches black to blackish brown. Leaves: petiole 3–9 mm long, 0.8–1.4 mm diam, grooved, indument as on branches; lamina ovate, oblong-elliptic to obovate or narrowly so, 6.2–22 by 2.8–9 cm, 2.1–3 times longer than wide, chartaceous, not punctate, above glabrous except primary vein glabrous or covered with ascending, whitish hairs, below covered with ascending to appressed, white-yellowish hairs 0.2–0.3 mm long, base cuneate, rounded to slightly subcordate, with thickened black margin, apex acute to acuminate, acumen to 15 mm long, secondary veins 6–11 per side, straight and halfway curving upwards, tertiary venation percurrent, slightly raised above. Inflorescences axillary or terminal, composed of solitary flowers or 2–6-flowered fascicle-like rhipidia; sympodial rachis 0.5–10 mm long, sparsely covered with ascending hairs, becoming glabrous; flowering pedicels 16–55 mm long, 0.5–0.6 mm diam, sparsely covered with ascending, reddish brown hairs; lower bract absent or ovate, c. 1 by 0.4 mm, densely covered with yellow-brown hairs; upper bract in lower half of the pedicel, broadly ovate, 0.5–0.9 by 0.5–0.7 mm, indument as on pedicel; flower buds globose. Flowers bisexual; sepals connate at the base, depressed ovate, 0.5–0.7 by 2–2.8 mm, apex rounded to acute, sparsely covered with white to yellowish hairs; receptacle 2.5–3 mm diam, flat; petals pale yellow, 6, in two whorls, outer petals broadly ovate, 4.7–5.5 by 4.6–5.8 mm, outside and inside densely covered with yellow-brown hairs, inner petals broadly ovate, 2.5–4 by 2.8–3 mm, indument as on outer petals; stamens 15–24, in one or two whorls, free, oblong, 0.8–1.6 mm long, filaments 0.5–0.9 mm long, broader than connective, thecae latrorse, almost convergent apically, only leaving a very small part of the connective visible, glabrous, staminodes absent; carpels 10–16(–21), subcylindric, 1.2–1.4 by c. 0.4 mm, densely hairy, ovules 2 or 3, lateral, stigma elongate, deeply bifurcate, 0.4–0.5 mm long, glabrous. Monocarps and seeds not seen.

Distribution — Cameroon, Central African Republic, Gabon.

Habitat & Ecology — Along forest road and on river bank. Altitude: 600–1300 m. Flowering: March, April, June, September.

Preliminary IUCN conservation status — Endangered (EN): B2ab(iii). EOO: 592 537 km 2, AOO: 28 km 2. This species has a wide distribution, but is only known from 5 unprotected localities and has only been collected once in the last 50 years.

Notes — 1. Monanthotaxis pellegrinii shares with M. bicornis the shape of the stamens, which have a filament wider than the connective and the thecae converging apically almost hiding the connective. Monanthotaxis pellegrinii differs from M. bicornis in the indument, which consists of ascending, reddish brown hairs on young branches, while M. bicornis has appressed, yellow-brown hairs on the young branches. They are not closely related as phylogenetic analysis places them in different clades ( Fig. 1 , clade H and I). In M. pellegrinii the leaf shape is highly variable, however, the type of M. pellegrinii has a leaf shape similar to M. bicornis , but it differs in the indument. Also the number of stamens is highly variable in this species. The type specimen and one other collection of north Gabon have 15–17 stamens in one whorl, while in 4 other collections the flowers have 24 stamens in two whorls. No other differences correlated to this difference in stamen number could be found. More material combined with DNA-based phylogenetic analyses are needed to verify if all specimens belong to the same entity or actually belong to 2 or more different (sub)taxa.

2. There is one fruiting specimen in the Republic of the Congo, which may belong to M. pellegrinii , however, the pedicels are very short, the leaf shape is different and it occurs in much drier forests than the other collections of M. pellegrinii . The fruit has 6 moniliform monocarps with each 2– 4 ellipsoid seeds. The monocarps are 32–41 by 7–8 mm, verrucose, apex rounded to apiculate, sparsely covered with ascending, yellow-brown hairs, and the stipes 7–8 mm long.

Figures

Fig. 7 a–g. Monanthotaxis bokoli (De Wild. & T.Durand) Verdc. a. Flowering branch; b. detail leaf abaxially;c. flower with three petals removed; d. outer petal, inside view; e. inner petal, inside view; f. stamen; g. carpel and longitudinal section of carpel. — h–m. Monanthotaxis pellegrinii Verdc. h. Flowering branch; i. flower with three petals removed; j. outer petal, inside view; k. inner petal, inside view; l. stamen; m. carpel and longitudinal section of carpel (a–g: Le Testu 5729; h–m: Le Testu 9028). — Modified from Le Thomas (1969) plate 41.

Fig. 1 Bayesian 50 % majority rule consensus tree of the genus Monanthotaxis. Asterisks at nodes indicate node support, i.e., *** Strong node support, ** moderate node support, * weak node support, see Hoekstra et al. (2018). The letters A to K with adjacent black bars indicate the clades. The triangles, circles and squares represent morphological characters of the species which are of some use to distinguis the clades. Green triangles = staminodes absent, red triangles = staminodes present. Green circles = petals in one whorl, red circles = petals in two whorls, yellow circles = petals in bud basally in one whorl, at the top outer petals overlapping the inner ones. Green squares = inflorescences extra-axillary or if cauliflorous also extra-axillary inflorescences present, red squares = inflorescences axillary, supra-axillary or cauliflorous, red and green squares = both extra-axillary and axillary inflorescences present.