Monotes africanus De Candolle (1868: 624

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 : 170-171

2. Monotes africanus De Candolle (1868: 624 emend, excl. specim. Kirk)

≡ Vatica africana Welw. ex Oliver (1868: 173) pro parte excl. var. hypoleuca , var. glomerata & var. glabra . ≡ Vatica africana var. denudans Welwitsch (1869: 16 ; Tab. V, Fig. 1 ).

Type: — ANGOLA. Huila, Lopolo, 1860, Welwitsch 1035 (BM! [barcode BM001209295, BM001209296], LISU! [barcode LISU234081, LISU234082, LISU234083], P! [barcode 00389101], COI!).

Shrub or small tree up to 8 m high; bark exfoliating in thin strips; branchlets greyish or brownish, glabrous to thinly pubescent. Leaf: petiole thinly pubescent, glabrescent, 5–15(–20) mm long, 1–2 mm in diameter; blade elliptic to oblong or obovate, (3.5–)5–10 × (1.5–) 2–5.5 cm, rounded to slightly cordate at the base, obtuse to emarginate at the apex; lateral nerves in 8–14 pairs (with a tendency to the formation of short subsidiaries), nearly straight but incurved at the apex and vanishing without reaching the margin of the leaf; veins much more prominent than reticulation on lower surface; upper surface finely reticulate, with reticulum generally orange-lepidote, typically bullate in the axils of lateral nerves and midrib (with a corresponding depression on the lower surface), glabrous except sometimes for the midrib and lateral nerves, with numerous punctiform yellow glands; lower surface concolorous, puberulous with very minute curled or coiled hairs mixed with some straight ones on the nerves and reticulation, the interreticular areoles generally glabrous; midrib and lateral nerves slightly depressed above and prominent beneath. Inflorescences axillary, 1.5–3(–5) cm long, ± condensed or lax, few-flowered, fulvous-tomentellous; peduncle 1–3 cm long, slender. Flower: pedicel 3–8 mm long; sepals ca. 2 mm long, densely woolly-rufous-tomentose; petals ca. 8 mm long, densely greyish subsericeous-tomentose; stamens with anthers produced into a large, emarginate or triangular lobe. Fruit subglobose, 10–15 mm in diameter, rounded to conical at the apex, sericeous; wings elliptic to obovate, 2.5–3.5 × 1.2–1.6 cm, yellowish or brownish.

Illustrations: — Figs. 3C , 4C , 8A .

Distribution: —Widespread in Upper Katanga.

Distribution elsewhere: — Angola, Malawi, Mozambique, Tanzania, Zambia.

Habitat and ecology: —Miombo woodlands; transition between Uapaceto-Combretetum katangense and Brachystegia boehmii woodland; Xerobrachystegion ( Schmitz 1971).

Uses: —Poles, tools; foodplant of the edible caterpillar of the cavorting emperor moth, Usta terpsichore ( Saturniidae ) ( Malaisse 1997).

Other representative specimens examined:—D.R. CONGO. Upper Katanga: Parc d’Elisabethville (Lubumbashi), 10 June 1922, Delevoy 929 (BR!); 12 km à l’ouest d’Elisabethville (Lubumbashi), forêt claire à Brachystegia utilis sur terre rougeâtre compacte et profonde, 14 July 1956, Duvigneaud & Timperman 2006 (BRLU!); Entre Mindingi et Menda, 13 km de Menda, forêt claire à Brachystegia floribunda sur terre ocre, 17 July 1956, Duvigneaud & Timperman 2079 (BRLU!); Menda, forêt claire à Brachystegia longifolia sur terre rouge légère, 22 July 1956, Duvigneaud & Timperman 2092 (BRLU!); entre Mukumbi et Swambo, forêt claire sur terre ocre compacte, 1 June 1957, Duvigneaud 3338 (BRLU!); Kasumbalesa, forêt claire de plateau à Brachystegia utilis sur sol brun à proximité des sources de la Luina, 3 December 1959, Duvigneaud 4379M (BRLU!); Sakania, forêt claire sur terre ocre caillouteuse à Brachystegia boehmii et B. spiciformis , 31 jan 1960, Duvigneaud 5361BM (BRLU!); Arboretum de l’Etoile, 5 km NE d’Elisabethville (Lubumbashi), forêt claire, January 1948, Schmitz 1246 (BR!); Welgelegen, alt. 1300 m, lambeau de forêt claire en bordure d’un marais à Rhynchospora candida , 8 February 1962, Symoens 9203 (BRVU!); Keyberg, forêt claire à Marquesia , près de la station expérimentale de l’INEAC, 3 February 1966, Symoens 12158 (BM!).

Discussion: —Glabrescent specimens are superficially similar to M. glaber ; the latter, however, differs in having yellow-green leaves often with an orange-tinged reticulum on the lower surface.

As already pointed out by Verdcourt (1989), the frequently used author combination “(Welw.) A.DC.” for M. africanus is not correct since De Candolle published his name in mid-July of 1868 while Welwitsch’s name Vatica africana was validated by Oliver in October 1868. See further nomenclatural discussion under Monotes hypoleucus .

References: — Bancroft (1937: 136; 1939a: 372); Catarino et al. (2013: 266); De Wildeman (1927a: 168); Duvigneaud (1949: 42; 1961: 415); Engler (1910: 615, Fig. 532); Engler (1921: 522); Figueiredo & Smith (2008: 67); Gilg (1899: 137; 1903: 307; 1908b: 292); Lebrun & Stork (1991: 144); Meerts (2016: 222); Verdcourt (1989: 8); White (1962: 262).

Figures

FIGURE 1. A. Principal Component Analysis of 14 variables. Projection of 81 samples on PC1 (27%) and PC2 (13%). Squares: Monotes caloneurus, circles: M. elegans, crosses: M. schmitzii, diamonds: M. hypoleucus. Apsin = depth of apical sinus, basin = depth of basal sinus, Dfr = fruit diameter, LL = Leaf length, Lw = leaf width, L/w = length/width ratio, lowcol = colour of lower surface of leaf, lowhair = density of hairs on lower surface, Lpet = petiole length, Lwings = length of calyx wings at fruiting stage, nerves = number of lateral nerves on one side of the midrib, shap = distance from base to largest width relative to leaf length, upcol = color of upper surface of leaf, uphair = density of hairs on upper leaf surface. B. Non metric multidimensional scaling, based on 14 variables. Projection of 81 samples on the first two axes. Squares: Monotes caloneurus, circles: M. elegans, crosses: M. schmitzii, diamonds: M. hypoleucus. See Appendix for the list of specimens included.

FIGURE 3 A–H. Details of lower surface of the leaf.A. Monotes adenophyllus var. adenophyllus (Duvigneaud 5112). B. M. adenophyllus var.homblei (Duvigneaud 4601). C. M.africanus (Duvigneaud 2006). D.M.autennei (Duvigneaud 5260). E.M.dasyanthus var.dasyanthus (Duvigneaud & Timperman 2341). F. M.dasyanthus var. heterotrichus (Duvigneaud 1141). G. M. dasyanthus var. mutetetwa (Duvigneaud 950). H. M. doryphorus (Duvigneaud 5267).

FIGURE 4 A–H. Details of upper surface of the leaf.A. Monotes adenophyllus var.adenophyllus (Duvigneaud 5044). B. M.adenophyllus var.homblei (Duvigneaud 4570). C. M.africanus(Duvigneaud 2006). D. M.autennei(Plancke 111/1532). E.M.dasyanthus var.dasyanthus (Duvigneaud & Timperman 2341). F. M. dasyanthus var. heterotrichus (Duvigneaud 4493). G. M. dasyanthus var.mutetetwa (Duvigneaud 950). H. M. doryphorus (Duvigneaud 5267).

FIGURE 8. Colour photographs of leaves in members of Monotes. A1-A2. M. africanus (Duvigneaud 2006: 2 leaves). B. M. doryphorus (Duvigneaud 5267). C. M. hirtii (Duvigneaud 3513). D. M. katangensis (Duvigneaud & Timperman 2641). E. M. pearsonii (Duvigneaud 5233). Scale bar = 5 cm.