Monotes rubriglans Bancroft (1937: 138)

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 : 193-194

13. Monotes rubriglans Bancroft (1937: 138) ; Bancroft (1939a: 358); Catarino et al. (2013: 272); Figueiredo & Smith

(2008: 67); Lebrun & Stork (1991: 144); Meerts (2016: 223)

Type: — ANGOLA. Huila, 12 July 1928, Bonnefoux & Villain 57 (holo-: P! [barcode P00389102]; iso-: BM! [barcode BM000603381], BRLU! (fragm.)) .

Small tree (height unknown). Twigs pubescent to densely tomentose; stipules reddish, ciliate, more or less persistent. Leaf: petiole 11–40 mm long, pubescent; blade very variable in shape (even on the same twig), ovate, ovate-elliptic, elliptic, obovate, more rarely suborbicular, (4.5–)6–17.5 × 3–13 cm, rounded to slightly cordate at the base, generally emarginate or, more rarely, with a short broad acumen, often with the main nerve protruding in a short blunt mucro; secondary nerves 8–14 pairs; basal gland red, subsidiary red glands present along secondary nerves or at their axil; upper surface of leaf glabrous to pubescent, markedly reticulate and generally more or less shining, with the costa and secondary nerves somewhat impressed and with a fringe of simple hairs; lower surface of leaf with the costa, secondary nerves and reticulum very prominent, almost glabrous to hirsute; secondary nerves anastomosing in arches tangent to the margin, with a tendency of some nerves to be distally forked or ramified; leaf margin often more or less sinuose, recurved, generally thickened by an intra-marginal vein; lower surface of blade concolorous to discolorous, with the areoles glabrous to stellate-pubescent; yellow glands present on veins and areoles. Inflorescence: a thyrse, in the axil of current year leaves or on previous year’s growth; peduncle 1–8 cm, pubescent; bracts reddish, ciliate, generally persistent; flowers: pedicel 1–2 mm long, sepals broadly ovate-elliptic 3–5 × 2–4 mm, petals 8–12 × 4–5 mm, whitish with a reddish tinge within, stamens 5–8 mm long, anther with conspicuous appendage. Fruit ovoid, ca. 10 × 7 mm, with a conical apex; wings obovate, 2.0–4.0 × 0.8–1.5 cm, pale reddish.

Discussion: — In Katanga, the collections that can be referred to Monotes rubriglans carry the most diagnostic traits of the species, i.e. the red basal gland, the tendency to form subsidiary glands, the reddish colours present in bracts, stipules and petals, and the markedly reticulate-areolate and more or less shiny upper surface of the leaf, with a fringe of cilia on the secondary nerves. The reticulation on the lower surface is also similar to the type, with the nerves anastomosing in arches tangent to the margin, and a tendency of some nerves to be distally forked or ramified. However, the Katangan collections depart from the type in having more pubescent twigs and leaves. They share a distinct, remarkable inflorescence architecture, having the flowers in long pedunculate thyrses on previous year’s growth under the leaves. The inflorescence appears to consist of a specialised twig comprising a few reduced leaves. This particular inflorescence architecture is considered unique within Monotes , where flowers are born in terminal panicles and/or in cymes in the axils of leaves on current year’s growth. We here propose to recognize the Katangan collections as a distinct subspecies.

Monotes rubriglans is a very poorly known taxon. For the type subspecies, in addition to the type specimen, Catarino et al. (2013) cite three collections from Angola. However, all of these depart from the type in many respects and probably do not belong here. More material is needed, especially from the type locality.