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

Fig. 8 A – D

Type.

S. Lisowski 23150 (holotype POZG [ POZG-V-0072770 ]), DR. Congo, Haut-Shaba [Haut-Katanga], Plateau des Kundelungu, env. 3 km au NW de la source occidentale de la Lutshipuka , steppe, 11 Jan 1971 .

Diagnosis.

Belongs in the group of species formerly comprising the genus Holostylon on account of the undivided style; closely related to C. foliatus , differing in the linear leaves, 1–4 mm wide, with strongly revolute margin.

Description.

Herb, annual or perennial, ca. 0.20–0.30 m high, roots not observed. Stem ascending to erect, subterete, simple, with short ascending hairs and sessile red glands, internodes ca. 1 cm. Leaves opposite or ternate, more rarely scattered, ascending to erect, sessile, blade linear, 1.5–3.5 × 0.1–0.4 cm, base truncate to rounded, apex blunt, margin strongly revolute, glabrous and punctate above, slightly pubescent on mid-vein and margins underneath and with many red sessile glands. Inflorescence simple, lax, 2–6 cm long, verticils spaced ca. 5 mm, mostly 2 - flowered, rachis shortly pubescent with ascending glandular and eglandular hairs, bracts ovate, acute, ca. 3 mm long, pedicels 5–7 mm long, with short ascending hairs, without a conspicuous joint. Flower: calyx 4 mm long at anthesis, elongating to ca. 9 mm in fruit, campanulate to tubular, tube straight to slightly curved, with orange sessile glands and short glandular and eglandular hairs, upper lip ovate-triangular, slightly recurved, 2 mm long, lateral lobes of lower lip triangular, median lobes of lower lip narrowly triangular, slightly longer; corolla ca. 12 mm long, purplish, tube sigmoid ca. 5 mm long, lower lip strongly keeled, ca. 7 mm long, shortly pubescent and with sessile pale glands, upper lip ca. 4 mm long. Anthers pouch-like; style undivided. Nutlets not observed.

Etymology.

Habitus and leaf shape are reminiscent of several species of Linaria ( Plantaginaceae ).

Distribution.

Endemic to DR. Congo, Haut-Katanga, Kundelungu Plateau.

Habitat and ecology.

Steppic savannah, ca. 1600 m elev.

Additional specimens.

None.

Note.

A very distinct species on account of the ternate linear leaves with strongly revolute margin.

Figures

Figure 8. Coleus linarioides Meerts & A. J. Paton A habit B leaf undersurface C detail of inflorescence D stamen (S. Lisowski 23150). Drawn by Hilde Orye. Scale bars: 1 cm (A); 5 mm (B, C); 1 mm (D).