Monanthotaxis seretii (De Wild.) 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 : 196-198

65. Monanthotaxis seretii (De Wild.) P.H.Hoekstra , comb. nov. — Fig. 6a , 28 ; Map 40

Popowia seretii De Wild., Ann. Mus. Congo Belge, Bot. 3 (1909) 76. — Enneastemon seretii (De Wild.) Robyns & Ghesq. (1933) 162. — Enneastemon schweinfurthii (Engl. & Diels) Robyns & Ghesq. var. seretii (De Wild.) Le Thomas (1969) 253. — Type: F. Seret 870 (holo consisting of 2 sheets: BR0000008804716,BR0000008820259), Democratic Republic of the Congo, Orientale, Bambesa, Poko Zobia, 4 May 1907.

Enneastemon angolensis Exell (1932) 210. — Type: J. Gossweiler 9488 (holo consisting of 2 sheets: BM000553823 , BM000553824 ; iso B100460755 , COI00004901 , K000198965 , LISC000269 , LISC000270 , US00098694), Angola, Malanje, rio Lui, Quibo-Quela , 1200 m, 3 Feb. 1931.

Enneastemon affinis Robyns & Ghesq. (1933) 163. — Lectotype (designated here): P. Quarré 2708 (lecto consisting of 5 sheets: BR0000008820457 , BR0000008820464 , BR0000008820563 , BR0000008820570 , BR0000008820587 ; iso K000198907 ), Democratic Republic of the Congo, Katanga,Kaniama,récolté a la Pastorale section I, Mutalala en Kil , Sept.1931.

Liana to 25 m long; young branches densely covered with appressed to ascending, reddish brown hairs 0.1–0.2 mm long, becoming glabrous; old branches reddish brown to dark brown. Leaves: petiole 5.5–13 mm long, 0.8–1.7 mm diam, slightly grooved, indument as on branches; lamina oblong-elliptic to obovate, 4.2–22.4 by 2.1–11.8 cm, 1.8–2.4 times longer than wide, subcoriaceous, not punctate, glaucous below, above sparsely covered with appressed to ascending, white hairs 0.1–0.2 mm long, primary vein covered with erect, yellowish

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hairs, becoming glabrous, below sparsely covered with appressed, yellowish hairs 0.1–0.2 mm long, base rounded to subcordate with thickened black margin, apex acute to shortly acuminate, acumen 5–10 mm long, secondary veins 7–10(–13) per side, straight or slightly curving, tertiary venation percurrent, hardly visible. Inflorescences axillary or supra-axillary, solitary, but more often in up to 6-flowered fascicle-like rhipidia; sympodial rachis cushion-like, up to 4 mm long, densely covered with reddish brown hairs c. 0.1 mm long; pedicels 5–17 mm long, 0.4–0.6 mm diam, fruiting pedicels 1–2.2 mm diam, indument as on rachis; lower bracts absent; upper bract placed halfway or in lower half of the pedicel, ovate to broadly ovate, 0.4–0.5 by 0.8–1 mm, indument as on rachis; flower buds globose. Flowers bisexual; sepals connate at the base, depressed ovate, 0.4–1 by 1.2–2 mm, apex obtuse to slightly acute, densely covered with appressed hairs, falling off in fruit; receptacle 2–2.5 mm diam, flat; petals colour in vivo unknown, in sicco the inner petals reddish brown on the base and yellowish brown near the top of the outside, 6, in one whorl, outer petals overtopping inner petals in bud, outer petals ovate to rhombic, 4.5–7 by 3.5–4.5 mm, outside and inside densely covered with appressed to ascending, reddish brown hairs, but hairs shorter to glabrous near base of inside, inner petals elliptic to rhombic, 3.2–5.9 by 2.2–3.4 mm, outside covered with ascending to erect hairs, inside densely covered with yellowish brown, very short hairs; stamens 9, in one whorl, free, clavate, 1.3–1.5 mm long, filaments 0.8–1 mm long, thecae extrorse, connective truncate, prolonged outward and inward, hiding the thecae, glabrous, but sparsely hairy on the underside of the inward appendage, staminodes absent; carpels c. 6, narrowly subcylindric to narrowly ellipsoid, 1.9–2 by 0.6–0.7 mm, grooved, densely hairy, ovules 5 or 6, lateral, stigma elongate, 0.4–0.5 mm long, glabrous. Monocarps 1–6, colour in vivo unknown, moniliform, 23–70 by 8–11 mm, slightly to clearly verrucose, densely covered with reddish brown, yellowish brown to whitish hairs 0.1–0.2 mm long, apex rounded to apiculate, apiculum to 3 mm long, stipes 4–8 mm long. Seeds 1–5, globose to ellipsoid, 10–12 by 8–11 mm, ochre-brown, apex rounded, raphe clearly visible.

Distribution — Democratic Republic of the Congo (Bas-Congo, Kasai-Oriental, Katanga, Kinshasa, Orientale), Angola ( Cabinda, Lunda Sul, Malanje).

Habitat & Ecology — In gallery forest, secondary forest and at forest at edge of savannas. Altitude: 470–1200 m. Flowering: November to May, July to September; fruiting: February to June, September and November.

Vernacular names — Democratic Republic of the Congo: Badamu (Zande name) (P. Gérard 4514) 1057044, Dupe Kasa keke (Babua name) (P. Gérard 3806) 1060891, Dupe kasa Sisi (Babua name) (P. Gérard 4995) 321695

Preliminary IUCN conservation status — Vulnerable (VU): B2ab(iii). EOO: 1 441 060 km 2, AOO: 80 km 2. This species is known from nine locations, of which three in nature reserves. This species has only been collected twice in the last 50 years and the majority of locations are under threat of logging and pressure of expanding populations.

Notes — 1. Monanthotaxis seretii belongs to the M. schweinfurthii -complex ( Fig. 1 , clade B) and can be recognized by the combination of having 6 carpels per flower and a reddish brown indument. Monanthotaxis capea also has these characters and can best be distinguished by the monocarps, which are strongly rugose-tuberculate in M. capea and weakly to strongly verrucose in M. seretii . Furthermore, M. seretii generally has a subcordate leaf base, but more collections from the north of the Democratic Republic of the Congo are needed to assess the exact boundaries in species delimitation between M. seretii and M. capea .

2. There is quite some variation in general appearance across the distribution area of M. seretii . The pedicel length is 5–8 mm in North and Central Democratic Republic of the Congo and 6–17 mm in Angola and Bas-Congo. Furthermore, the hairs on the monocarps are reddish brown in Angola, but yellowish brown to whitish brown in the Democratic Republic of the Congo.

Figures

Map 40 Distribution of Monanthotaxis schweinfurthii (Engl. & Diels) Verdc. (■) and M. seretii (De Wild.) P.H.Hoekstra (●).

Fig. 6 a. Monanthotaxis seretii (De Wild.) P.H.Hoekstra. Fruiting branch. — b–h. Monanthotaxis capea (E.G.Camus & A.Camus) Verdc. b. Flower bud, seen from above; c. flower bud, side view; d. stamen, outer, inner and side view; e. carpel; f. fruiting branch; g. fruiting branch; h. seed. — i. Monanthotaxis biglandulosa (Boutique) P.H.Hoekstra. Fruiting branch. — j–m. Monanthotaxis foliosa (Engl. & Diels) Verdc. j. Flowering branch; k. flower bud, seen from above; l. stamen,outer and side view; m.carpel (a: J.L.P. Louis 11405; b–h: Hallé 3561; i: Bamps 600; j–m: Le Testu 2108). — Modified from Le Thomas (1969) plate 44.

Fig. 28 Monanthotaxis seretii (De Wild.) P.H.Hoekstra. a. Flowering branch; b. fruiting branch; c. flower bud seen from above;d. longitudinal section of flower; e. stamen, outside view; f. stamen, side view; g. carpel; h. longitudinal section of carpel; i. young fruit; j. longitudinal section of monocarp (based on Toussaint 127 and 396). — Modified from Boutique (1951a) plate 36.

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.