Monotes duvigneaudii Meerts, 2017

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 : 177-179

6. Monotes duvigneaudii Meerts , sp. nov.

Type: — D.R. CONGO. Upper Katanga (administrative province of Lualaba), Nzilo, forêt verger à Monotes div. sp., enrochée, sur phyllades kibariennes, 27 January 1960, Duvigneaud 5268M4 (holo-: BRLU! [barcode BRLU0004158]; iso-: BRLU!) .

Diagnosis:— Differs from all other species of Monotes except M. doryphorus by the combination of ovate-lanceolate leaves with acute-acuminate apex and glabrous upper surface, and from M. doryphorus by the inflorescence in a terminal congested panicle (vs. small axillary cymes), the broader leaves (3.5–6.5 cm wide vs. 1.5–3.6) and the thicker petiole (ca. 2 mm thick vs. less than 1 mm).

Small tree (up to 5 m); leafy twigs channelled, ca. 3 mm in diameter, shortly and densely pubescent, glabrescent. Leaf: petiole 7–20(–25) mm long, 1.5–2 mm thick, densely and shortly pubescent, often canaliculated; blade ovate or ovate-elliptic to lanceolate, (6–)7.5–15 × (2–) 3.5–6.5 cm, broadest at the lower third, l/w ratio (1.5–)2–3.5, rounded to slightly cordate or rarely cuneate at base, long acuminate or rarely acute at apex, rather coriaceous; basal gland generally narrowly elliptic (more rarely round), strongly depressed, reddish; upper surface glabrous except the margin which has a fringe of very short fasciculate hairs, markedly reticulate, reticulum orange-tinged; secondary nerves 13–18 pairs, slightly curved, anastomosing just before the margin or tangent to the margin, secondary nerves not depressed; margin slightly thickened and recurved; lower surface of leaf generally strongly discolorous, white or whitish to pale greyish, with a continuous layer of very short stellate hairs entirely covering areoles and reticulum, sparser on the secondary nerves, or, more rarely, concolorous ( var. concolor ); nerves slightly prominent, pale orange-tinged, with a sparser layer of stellate hairs and a few short straight appressed hairs on the costa. Inflorescence a more or less condensed terminal panicle, 4–8 × 3–4 cm, consisting of subsessile narrow racemes or cymes 1–5 cm long, often with a few axillary racemes at the base, rarely consisting only of axillary racemes; axes densely pubescent. Flower: pedicel 1–2 mm long; floral bud ovoid-conical; sepals ovate, ca. 2 × 1.5 mm, apex obtuse, slightly carinate, densely sericeous tomentose; petals triangular-ovate, 7 × 2.5–3 mm, ca. 6-nerved, sericeous tomentose outside, almost glabrous inside; anther ca. 0.7 mm long, with short pointed apical appendage; ovary densely hirsute, apparently trilocular, thick-walled. Fruit unknown (but see var. concolor ).

Eponymy: —The new species is dedicated to Paul Duvigneaud (1913–1991), professor at Brussels University, the unrivalled specialist on the taxonomy of Monotes , who collected several thousands Monotes specimens in southern D.R. Congo between 1948 and 1960.

Variation:— Density of stellate hairs on the lower surface of the leaf is very variable; two varieties can be recognized.