Monotes duvigneaudii Meerts 2017, sp. nov.
Creators: name: Meerts, Pierre
name: Rougelot, Quentin
name: Sosef, Marc
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Malvales
Dipterocarpaceae
Monotes
Monotes duvigneaudii

description: 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.
description: Published as part of 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, pp. 151-205 in Phytotaxa 308 (2) on pages 177-179, DOI: 10.11646/phytotaxa.308.2.1, http://zenodo.org/record/13701270