Coleus pseudoschizophyllus Meerts & A. J. Paton, 2024

Meerts, Pierre J. & Paton, Alan J., 2024, The genus Coleus (Lamiaceae) in Central Africa (Democratic Republic of the Congo, Rwanda, Burundi), with the description of 15 new species, PhytoKeys 246, pp. 71-178 : 71-178

Coleus pseudoschizophyllus Meerts & A. J. Paton sp. nov.

Fig. 16 A – F

Type.

DR. Congo, Haut-Katanga, Marungu, Katomia , 18 Apr 1939, P. J. J. Vanden Brande 55 (holotype BR [ BR 0000016832183 ]) .

Diagnosis.

Closely related to C. schizophyllus on account of pinnatisect leaves and tuberous rootstock, differing by the conspicuously exserted sigmoid corolla tube, larger leaves, exserted stamens, tightly appressed indumentum and lack of glandular hairs in the inflorescence. It is also very closely related to C. welwitschii , differing by the jagged to pinnatisect leaves and rootstock with tubers.

Description.

Perennial herb, or suffrutex, 0.30–0.80 m high, from a thick rhizomatous rootstock, with fusiform tubers up to 5 cm long. Stem ascending to erect, the lower part woody, defoliated, purplish, strongly quadrangular, thinly puberulous with short adpressed retrorse hairs, upwards more densely puberulous and with red sessile glands, with a few long patent hairs at nodes, branched. Leaves opposite, petioled, often with fascicles of young leaves in the axils, ascending to spreading; blade ovate to trullate, 1.0–2.8 × 0.6–2.5 cm, apex acute, base more or less abruptly contracted and then attenuated into the petiole, margin markedly recurved, jagged to pinnatisect, with 3 to 6 lobes on either side, apical lobe narrowly oblong-triangular 3–5 mm long, upper surface dark green in herbarium, appressed pubescent, ca. 3 pairs of secondary veins, markedly impressed, lower surface markedly paler, pubescent on venation, this prominent, with dense red sessile glands; petiole 0.5–1.5 cm long, narrowly winged over the whole length, canaliculate, margin strongly recurved. Inflorescence lax, 8–10 cm long, 9–16 mm wide at anthesis (corolla excluded), with 12–15 verticils, spaced 6–10 mm, bracts ovate, cucullate, acuminate, 2–3 mm long, not forming a coma, ciliate, soon caducous, cymes sessile or with 1 - mm long peduncle, of 5–12 flowers, cincinni 2–4 mm long, pedicels 2–4 mm, appressed pubescent, curved at tip, inserted very eccentrically in front of calyx upper lobe. Flower: calyx ca. 1.5 mm long at anthesis, pubescent, with red sessile glands, fruiting calyx 4–5 mm long, tubular, tube with 10 prominent ridges, throat truncate; posterior lip obovate, slightly recurved, very shortly decurrent, rounded to apiculate, ca. 2 mm long, lateral lobes oblong, ca. 2 mm long, rounded to truncate, median lobes of anterior lip fused into a 3–4 mm long linear lip, with teeth acute. Corolla white, 7–11 mm long, very shortly pubescent or puberulent on lobes, with red sessile glands, tube strongly sigmoid, 3–5 mm long, the sigmoid part long exserted, upper lip ca. 1 mm long, shallowly 4 - lobed, much shorter than lower, lower lip ca. 4–5 mm long, 1.5–2 mm deep, somewhat upwardly curving, stamens exserted, filaments fused, anther ca. 0.5 mm long, style very shortly bifid, the branches often not divergent. Fruit: nutlets not observed.

Etymology.

The species superficially resembles Coleus schizophyllus (Baker) A. J. Paton on account of the deeply lobed leaves.

Distribution.

Endemic of SE DR. Congo (Haut-Katanga, Marungu Massif).

Habitat and ecology.

Rock crevices on mountains, scrub, steppic savannah on rocky soil (rhyolite); ca. 1600–2450 m elev.

Additional specimens.

DR. Congo, Haut-Katanga, Marungu, Ndawa, 2200 m elev., Apr 1944, L. Dubois 1140 ( BR); Marungu Massif, Katomia, 18 Apr 1939, P. J. J. Vanden Brande 67 ( BR); Marungu, Katuba, broussailles sur affleurement de rhyolithes, 27 Jun 1957, P. Duvigneaud 3744 L ( BRLU); Marungu, Env. Kasiki, Mont Kilonge, 12 Jun 1969, S. Lisowski, F. Malaisse, J. - J. Symoens 6518 ( POZG); Marungu, 10 km NNE Kasiki, sommet Lusale, 2450 m elev., 26 Nov 1969, S. Lisowski, F. Malaisse, J. - J. Symoens 8460 & 8460 a ( POZG); Marungu, 7 km WSW de Luonde, 16 Feb 1970, S. Lisowski, F. Malaisse, J. - J. Symoens 9768 ( POZG); Marungu, Mont Zuiba, steppe, 21 Feb 1970, S. Lisowski, F. Malaisse, J. - J. Symoens 10483 ( POZG).

Figures

Figure 16. Coleus pseudoschizophyllus Meerts & A. J. Paton A habit B leaf C detail of inflorescence D flower E fruiting calyx A (except roots) B – D L. Dubois 1140 A (roots only) E P. J. J. Vanden Brande 55. Drawn by Hilde Orye. Scale bars: 1 cm (A, B); 2 mm (C); 3 mm (D); 1 mm (E).