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

Fig. 5 A – F

Type.

DR. Congo, Haut-Katanga, Parc national de l’Upemba, flancs du muleshi, stream Sense , 1400 m elev., 24 Feb 1948, G. F. de Witte 3455 (holotype BR [ BR 0000017707978 ]; isotype K) .

Diagnosis.

Related to Coleus bojeri and other species formerly referred to the genus Solenostemon on account of the lower calyx lobes fused into a lip, differing in the following combination of traits: rootstock bearing fusiform tubers, petiole winged over the whole length, leaf apex acute to acuminate, pedunculate cyme, longer pedicels (mostly 3–7 mm long), longer fruiting calyx (5–7 mm long).

Description.

Perennial herb, ca. 0.3–0.9 m high; rootstock fibrose, with a fascicle of fusiform tubers 1–3 cm long (rarely collected). Stem erect, most often simple, occasionally sparingly branched, quadrangular, puberulent, with very short adpressed retrorse hairs and red sessile glands, becoming denser and patent in the inflorescence. Leaves opposite, ascending, petiolate, occasionally with fascicules of young leaves in the axils in robust specimens; blade thin, membranous, ovate to narrowly ovate, apex acute to long acuminate (often obtuse in lowermost leaves), base rounded to cuneate, then attenuate and decurrent on the petiole, margin regularly crenate to serrate (ca. 2–3 teeth / cm), (2.6 –) 6–8.5 × (0.8 –) 1.2–3.8 cm, 3–5 pairs of secondary veins, upper surface subglabrous to very shortly pubescent, with appressed hairs pointing to tip, lower surface very shortly pubescent on mid-vein (retrorse hairs) and reticulation, glabrous elsewhere save numerous red sessile glands (ca. 20 / mm 2); petiole 0.7–3.5 (– 4.5) cm long, very narrowly winged, ciliate. Inflorescence terminal, simple or with 1 or 2 pairs of basal branches, lax, (6 –) 10–30 cm long, 15–25 mm wide (corollas excluded) at anthesis, up to 4 cm wide in fruit, verticils 10–15 (– 40) mm apart, bracts membranous, cucullate, ovate-elliptic, ca. 6 b × 3 mm, contracted into an acumen, caducous or occasionally persisting, shortly pubescent outside and with red sessile glands; cymes with a 1–8 mm long peduncle, ascending to spreading, the lowermost cymes dichasial, with the basal branches diverging at an open angle, 7–11 (– 19) - flowered, branches with mixed indumentum of papillae and short spinulose hairs, cincinni elongating to 2 cm in fruit, pedicel variable in length in a cyme, (1 –) 3–7 (– 12) mm long, decreasing in length from base to top of cyme, inserted very eccentrically opposite the upper calyx lobe. Flower: calyx ca. 2 mm long at anthesis, very shortly pubescent and with red sessile glands, fruiting calyx 5–7 mm long, tube 1.5–2 mm long, upper lobe ovate, ovate-elliptic to obovate-elliptic, ca. 3 mm long, acute to rounded, recurved, slightly decurrent, lateral lobes ca. 1.5–2 mm long, truncate to obtuse, often slightly contracted near middle, lower lobes fused into a linear lip ca. 4 mm long, markedly longer than the other lobes, straight to slightly curved upwards distally, ending in two subaristate teeth ca. 1.5–2 mm long; corolla ca. 12–13 mm long, tube strongly sigmoid, longer than calyx, widening near throat, lower lip. ca. 7 mm long, 3–4 mm deep, with red sessile glands, upper lip ca. 2–3 mm long, bilobate; staminal filaments fused, anthers subglobose, connective often with 2–3 red sessile glands. Nutlets subglobose, smooth, pale brown, densely red-speckled, ca. 1 mm.

Etymology.

Dedicated to Hilde Orye, eminent botanical illustrator, chairwoman of the association of Belgian botanical artists, who produced all the original illustrations of this article.

Distribution.

Endemic of SE DR. Congo (Haut-Katanga).

Habitat and ecology.

Miombo woodland, scree, rocky hills; 800–1500 m elev.

Additional specimens.

DR. Congo, Haut-Katanga, Mukulakulu, forêt claire sur sol caillouteux, 24 Mar 1953, De Troyer 56 ( BR); Parc national de l’Upemba, rive droite de la Kalule Nord, contreforts du Mont Kia, près de Biamabwa, 1090 m elev., forêt katangaise d’altitude, 28 Feb 1949, G. F. de Witte 5644 ( BR); Versant N du Mont Kia, rive droite de la Kalule Nord, forêt katangaise d’altitude, saxicole sur éboulis, vers 1090 m elev., 1 Mar 1949, G. F. de Witte 5679, 5689, 5690 ( BR); Kundelungu, 830 m elev., forêt claire, exp. SO, pente 45 °, 29 Jan 1954, R. Desenfans 4974 ( BRLU); Fungurume, Shandiranzoro west, 21 Mar 2007, F. Malaisse & E. Kisimba 372 ( BR).

Notes.

1. C. hildei belongs to the group of species formerly referred to the genus Solenostemon (lower calyx lobes fused into a lip). It has affinities with the Coleus bojeri complex. It differs in the tuberous roots, the much taller habit, the pedunculate, dichasial cymes, the longer pedicels, the larger fruiting calyx and the winged petiole.

2. Vernacular name: tombwe (in kiluba).

Figures

Figure 5. Coleus hildei Meerts & A. J. Paton A habit B detail of pubescence of lower surface of mid-vein C cyme D flower E fruiting calyx and pedicel F stamen A De Troyer 56 & G. F. de Witte 5644 (tubers) B, C G. F. de Witte 3455 D G. F. de Witte 5679 E G. F. de Witte 5689 F G. F. de Witte 5679. Drawn by Hilde Orye. Scale bars: 1 cm (A); 1 mm (B); 2 mm (C); 2.5 mm (D); 1 mm (E); 0.5 mm (F).