Coleus chevalieri Briq.

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 chevalieri Briq. , Mém. Soc. Bot. France 8: 287. 1917.

Figs 1 C, D , 2 C

= Coleus delpierrei De Wild. , Bol. Soc. Ibér. Ci. Nat. 19: 119. 1920. Type: DR. Congo, Ubangi-Uele, Van Kerkhovenville [Watsa], 1904, A. Delpierre s. n. (lectotype BR [ BR 0000006261559 ], designated here), syn. nov.

Type.

Central African Republic, Haut-Oubangui, Krébédjé (Fort Sibut), vallée de la moyenne Tomi, bord d’un sentier sur un plateau ferrugineux, 8 Nov 1902, A. Chevalier 5662 (holotype P [P 00450788], [P 00450786]; isotype BR [ BR 0000006245498 ], G [ G 00437733]).

Description.

Annual herb, 0.15–0.70 m high, rootstock fibrose, without tubers. Stem erect, quadrangular, generally much branched from base, with short appressed retrorse hairs and red sessile glands, often purplish. Leaves opposite, ascending to spreading, petiole (0.2 –) 0.8–3.5 (– 4.5) cm long, narrowly winged in upper half, blade occasionally red spotted in the middle, ovate, narrowly ovate, 3–10 (– 11) × 1–4 (– 5.5) cm, mostly 2–3 times as long as broad, apex generally obtuse, rarely acute, base cuneate, shortly attenuate in the petiole, 4–8 pairs of secondary veins, occasionally impressed, margin crenate to obtusely serrate (teeth obtuse to rounded), subglabrous to very shortly pubescent above, shortly pubescent on veins beneath (antrorse or retrorse hairs). Inflorescence spiciform, (3 –) 5–12 cm long, 8 mm wide at anthesis (corolla excluded), congested, occasionally more lax, moderately dense at fruiting, up to 32 cm long, 10–15 (– 20) mm wide at fruiting, with (5 –) 15–30 verticils typically spaced 5–10 mm, the lowermost ones occasionally up 25 mm, bracts persistent, at first erect and cucullate, soon reflexed, ca. (1.5 –) 4–6 × (0.5 –) 2–3 mm long, ovate-triangular, sessile, acute to acuminate, occasionally almost caudate, ciliate, upper surface glabrous, lower surface sparsely pubescent and with red glands, forming a short apical coma; cymes sessile, ca. 11 (– 17) - flowered, cincinni ascending, elongating to 2–3 (– 6) mm, pedicels ca. 2–3 mm long. Flower: calyx shortly pubescent, with red sessile glands, ca. 2 mm long at anthesis, fruiting calyx subglabrous to shortly pubescent, 3.5–4 mm long, narrowly tubular, slightly constricted a throat, upper lip often purplish tinged, ovate-elliptic to obovate-elliptic, ca. 2.5 mm long, acute to more rarely rounded, recurving, not decurrent, lateral lobes truncate, ca. 1 mm long, median lobes of lower lip fused, linear, ca. 2 mm long, with two acute points, slightly curving upwards; corolla blue to pale mauve, with or without red sessile glands, ca. 8–12 mm long, tube 2.5–3 mm long, sigmoid, lower lip 3–7 mm long. Fruit: nutlets yellowish-brown with red speckles, globose ca. 0.8 mm diam., smooth.

Distribution.

Cameroon, Central African Republic, DR. Congo.

Habitat and ecology.

Savannah, dry woodland, fallow fields, often on lateritic crust, 300–1000 m elev.

Additional specimens.

DR. Congo, Bas-Katanga, Haut-Lomami, Kaniama, 20 Apr 1947, W. Mullenders 295 ( BR); Forestier Central, Eala, 28 Sep 1937, G. Couteaux 338 ( BR); Ikulu, 14 Feb 1940, Freyne 4 ( BR); Bambesa, 1936, Pittery 424 ( BR); Route Niangara-Kisangani, 55 km d’Isiro, vers Wamba, 20 Apr 1936, J. Louis 1738 ( BR); Asaka, 30 Oct 1923, Nannan 623 ( BR); Ubangi-Uele, Doruma, 10 Sep 1933, A. M. De Graer 101 ( BR); Garamba, 10 Sep 1951, H. De Saeger 1396 ( BR, K); Uele-Nipoko, entre Niangara et Wamba, Jun 1931, J. Lebrun 3199 ( BR); Yakuluku, 29 Sep 1953, P. Gérard 790 ( BR).

Central African Republic, Haut-Oubangui, Yalinga, 18 Sep 1921, G. Le Testu 3256 (P); 60 km N of Bambari, 26 Nov 1928, Ch. Tisserant 2296 (P); Oubangui-Chari, Koukourou, Sep. 1957, J. Trochain 10648 (P).

Cameroun, Sabal Maba, 60 km NNE Tibati, 23 Sep 1963, R. Letouzey 5920 (P).

Notes.

1. Within the C. bojeri complex, this species is easily recognised on account of the persistent bracts, long spiciform inflorescence with congested, closely-spaced verticils; the leaves tend to be obtuse, with blade more than 2 × as long as broad, with numerous secondary veins, but these traits are more variable.

2. Robyns and Lebrun (1928) had already synonymised C. delpierrei De Wild. and C. chevalieri Briq.

3. Near the southern margins of the species’ distribution range, specimens intermediate between C. chevalieri and other species occur: e. g. L. Pynaert 1702 (intermediate with C. bojeri ); H. Vanderyst 34394 (intermediate with C. welwitschii ); S. Risopoulos 146 (intermediate with C. botryosus ); L. Pynaert 1092, G. Couteaux 338 (BR) (intermediate with C. brazzavillensis ).

4. Lectotypification of Coleus delpierrei De Wild. De Wildeman (1920) cited two syntypes: A. Delpierre s. n. ( BR [ BR 0000006261559 ]), DR. Congo, Vankerkhovenville [Watsa], 1904 & A. Delpierre s. n. ( BR [ BR 0000006261887 ]), Niangara, 1904. Both match the protologue; [ BR 0000006261559 ] is selected because its inflorescence is better developed.

5. The most typical specimens of C. chevalieri occur in the Sudanian part of DR. Congo, in the region of Ubangi-Uele, where they grow on lateritic crust. In other regions of DR. Congo, C. chevalieri is often less typical and intermediates with other species of the C. bojeri complex occur.

Figures

Figure 1. Coleus bojeri complex, details of inflorescence architecture and stem pubescence in four species A, B Coleus bojeri Benth. (T. Sperry 179) C, D Coleus chevalieri Briq. (P. Gérard 4297) E, F Coleus collinus Robyns & Lebrun (J. Lebrun 9041) G, H Coleus heterotrichus Briq. (M. Micha 300). Drawn by Hilde Orye. Scale bars: 1 mm (B, D, F, H); 2 mm (A, C, E, G).

Figure 2. Coleus bojeri complex, leaf shape in four species A Coleus collinus (J. Lewalle 1936) B Coleus bojeri (T. Sperry 179) C Coleus chevalieri (P. Gérard 4297) D Coleus heterotrichus (P. Quarré 3159). Drawn by Hilde Orye. Scale bar: 1 cm.