Monotes adenophyllus Gilg (1895: 275

Meerts, Pierre, Rougelot, Quentin & Sosef, Marc, 2017, Revision of the genus Monotes (Dipterocarpaceae) in D. R. Congo, with implications for Angola and its distinction from Marquesia, Phytotaxa 308 (2), pp. 151-205 : 160

1. Monotes adenophyllus Gilg (1895: 275 ; 1899: 135); Engler (1921: 522)

Type: — TANZANIA. Ugogo , Pori , Pa-Kabombue , in trockener Steppe, Böhm 31a (holo-: B†; photo: BM!, BRLU!, K!) .

Small tree up to 8 m (?); branchlets brownish, tomentellose. Leaf: petiole 10–30 mm long, 2–3 mm in diameter; blade rounded to shortly ovate, more rarely broadly ovate-elliptic, with length to width ratio typically <1.5, truncate to slightly cordate at the base, rounded, truncate to slightly emarginate at the apex, 6–16(–19) × 4–13(–15.5) cm, concolorous or discolorous; secondary nerves 9–11(–13) pairs; upper surface ± scaberulous, reticulate, with hairs fasciculate and simple, (0.15–) 0.2–0.7 mm long, clearly discernible by touch (surface harsh or roughish), developed on cushion-like emergences of the leaf blade, sometimes only sparsely pilose and glabrescent; secondary nerves above without glands at the axils, reticulum more or less impressed, often giving a quilted or bullose appearance; lower surface with reticulum prominent or not, glabrous to relatively densely hairy, with hairs 0.2–1.5 mm long, straight, flexuous, curly to crispate, sometimes almost woolly, shorter to longer than areole diameter; areoles 1–2 mm in diameter, glabrous or with stellate hairs, often with yellow glands. Inflorescences 2–12 cm long, axillary, brown-tomentellous, lax, on a 1–3(–6) cm long peduncle; pedicels 2–5 mm long. Flower: sepals 2.5–3.5 mm long, rufous-cottony-tomentose; petals densely sericeous-tomentose, 5–11 × 2.5–3.5 mm; stamens with anthers produced in a conspicuous apical appendage. Fruit subglobose, 12–15 mm in diameter, subsericeous-tomentellous, mucronate at the apex; wings generally broadly elliptic to obovate, sometimes oblong and narrower, (1.5–)2.5–5(–7) × 1–3 cm, yellow to brownish or, more rarely, purplish.

Discussion: — Monotes adenophyllus shows extensive variation in indumentum of the lower surface of the leaf, including forms that are almost completely glabrous. Duvigneaud (1949, 1961) recognized four infraspecific taxa (by order of decreasing pubescence: “ albidus”, “ homblei ”, “ paucipilosus”, “ glabrescens”). However, the variation is essentially quantitative and extremely difficult to classify. A more synthetic treatment, with only two varieties is much more realistic. Due to the virtually continuous pattern of variation, and considering that those taxa are apparently sympatric over most of their fairly large distribution range, the rank of variety seems more appropriate than the rank of subspecies adopted by Duvigneaud (1961) and later authors ( Verdcourt 1989; Catarino et al. 2013).