Coleus esculentus var. primulinus Meerts & Paton 2024, comb. et stat. nov.

Coleus esculentus var. primulinus (Baker), comb. et stat. nov. Plectranthus primulinu s Baker in Bull. Misc. Inform., Kew 107: 292. 1895. Type: Zambia, Mwero Plateau, 1894, A. Carson 36 (holotype K [K 000430746]). (Basionym) Description. Closely related to var. densus, differing in the much shorter thyrses, with rachis obsolete, mostly grouped into a spiciform inflorescence in the upper part of the stem; calyx lobes 2–3 mm long, equalling the tube. Distribution. Angola, Zambia, DR. Congo, W Tanzania. Habitat and ecology. Savannah, wooded savannah, in DR. Congo often on Cu / Co or Mn rich soil, 1170–1830 m elev. Additional specimens. DR. Congo, Haut-Katanga, Upemba, Piste vers Mitwaba, 12 Apr 1947, G. F. de Witte 2488 (BR); Kasompi Est, Jul 1956, P. Duvigneaud & J. Timperman 2051 (BRLU); Kabwelunono copper hill, Jun 1997, F. Malaisse, E. Kisimba, Y. Muzinga 134 (BR); Kwatebala copper hill, May 2007, I. Parmentier 4347 (BR; WAG); Upemba, tête de source de la Katuba, Aug 1934, P. Quarré 4213 (BR); Kipopo, 20 May 1982, M. Schaijes 1397 (BR); Chabara, 11 Apr 1990, Tropmetex 224 (BR, MO). Notes. 1. Previous treatments (Paton et al. 2009, 2013) synonymised Plectranthus primulinus with Coleus densus. However, in DR. Congo, the two morphs can be readily recognised even though intermediates occur; therefore, we propose to recognise them at varietal rank. They occur in different habitats, var. primulinus being particularly frequent in steppic savannah on metal-rich soil in Haut-Katanga, where var. densus is rarely observed. 2. Specimens collected in the rainy season consist of leafy shoots without flowers, with leaves steadily decreasing in size upwards, the upper ones bract-like and often forming an apical coma; specimens collected in the dry season are mostly leafless and bear inflorescences in the upper part of the stem. Some specimens have particularly large leaves (up to 20 × 8 cm) with velvety tomentose indumentum (e. g. G. F. de Witte 2488).