Coleus heterotrichus 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 heterotrichus Briq. , Bull. Soc. Roy. Bot. Belgique 40: 40. 1901.

Figs 1 G – H , 2 D

= Coleus claessensii De Wild. , Bol. Soc. Ibér. Ci. Nat. 19: 117. 1920. Type: DR. Congo, Mobwasa, 1910, J. Claessens 741 (lectotype BR [ BR 0000006261863 ]; isolectotype BR [ BR 0000006262198 ], designated here), syn. nov.

≡ Calchas claessensii (De Wild.) P. V. Heath , Calyx 5: 160. 1997.

= Coleus ringoetii De Wild. , Contr. Fl. Katanga: 174. & Ann. Soc. Sci. Bruxelles 41 (2): 50. 1921. Type: DR. Congo, Shinsenda, Mar 1912, A. Ringoet 546 (holotype BR [ BR 0000006262907 ], [ BR 0000006263232 ]), syn. nov.

= Coleus termetophilus De Wild. , Contr. Fl. Katanga: 175. Ann. Soc. Sci. Bruxelles 41 (2): 50. 1921. Type: DR. Congo, Kundelungu, swamps, 13 Mar 1908, T. Kassner 2618 (lectotype BR [ BR 0000008732170 ], right-hand specimen only; designated here; isolectotype Z [Z- 000018897]), syn. nov.

= Coleus quarrei Robyns & Lebrun , Rev. Zool. Bot. Africaines 16: 3. 1928. Type: DR. Congo, Elisabethville [Lubumbashi], ferme de Kibembe, 30 Jul 1927, P. Quarré 608 (holotype BR [ BR 0000006262570 ]), syn. nov.

=? C. eetveldeanus Briq. , Bull. Soc. Roy. Bot. Belgique 37: 73. 1899. Type: DR. Congo, Haut-Katanga, M‘Toa, 15 May 1899, G. Descamps s. n. (holotype BR [ BR 0000008109156 ]).

Type.

DR. Congo, Bolobo, Jun 1891. F. Demeuse 455 [“ 1155 ” in the protologue in error] (holotype BR [ BR 0000021454103 ]; isotype G [ G 00435192]).

Description.

Annual herb, occasionally scrambling, aromatic, (0.15 –) 0.25 – 0.90 (– 2.00) m high; rootstock fibrose, without tubers. Stem erect, simple or branched, quadrangular, somewhat lignified in lower part in robust specimens, in the lower part with very short, papilliform (ca. 0.1 mm long) patent to recurved hairs and sessile red glands or very short glandular patent hairs and sparse longer patent hairs especially at nodes, in the inflorescence with mostly very short (ca. 0.1 mm long, papilliform), patent to slightly recurved eglandular and gland-tipped hairs, and sparse long multicellular patent hairs (ca. 1 mm long), these sometimes almost lacking. Leaves opposite, ascending to spreading, petiole 1.0–4.5 (– 10) cm long, pubescent like the stem, with dense very short hairs (retrorse or patent) and sparse, much longer patent hairs; blade occasionally with a purplish spot in the middle, ovate to broadly ovate-triangular, (1.0 –) 3.0–7.0 (– 12) x (1.0 –) 2.5–5.0 (– 8.5) cm, apex acute to obtuse, base broadly rounded, or truncate to subcordate and then shortly attenuate into the petiole, membranous, ca. 4–5 pairs of secondary veins, margin crenate, upper surface with sparse, appressed, antrorse hairs, lower surface very shortly pubescent on veins, (occasionally papillate over the whole surface), rarely with long patent hairs on veins, with red sessile glands. Inflorescence lax, (5 –) 12–32 (– 40) cm long, 2–6 (– 10) cm broad at fruiting, with (2 –) 7–20 (– 28) verticils spaced 10–25 (– 40) mm, bracts whitish, ovate, acuminate, cucullate, 2–7 mm long, ciliate, early deciduous (very rarely persistent at lower verticils), cyme with a 1–2 mm long peduncle, often dichasial, each cyme consisting of two subequal cincinni, diverging at right angle, elongating to 5–20 (– 50) mm in fruit, lax, each with 4–7 (– 20) flowers (i. e. cyme with 9–15 (– 41) flowers), spaced ca. 3 mm, pedicels 2–5 (– 6) mm long, with very short papilliform, eglandular and gland-tipped hairs and occasional longer multicellular hairs and red sessile glands, pedicel curving at tip, inserted eccentrically in front of calyx upper lobe. Flower: calyx 1.5 mm long at anthesis, 3–5.5 mm in fruit, shortly pubescent and with red sessile glands, tube campanulate ca. 2 mm long, throat truncate, upper lobe broadly ovate to almost round, 1.5–2.5 × 1.5–2.5 mm, apiculate, very shortly decurrent, curving upwards, lateral lobes of lower lip oblong-rectangular, truncate, lower lobes fused into an oblong linear lower lip ca. 2.5–3 mm long with two acute teeth. Corolla blue, with red sessile glands, 8–13 mm long, tube strongly sigmoid 4 mm long, widening near throat, upper lip 1–2 mm long, lower lip 4–7 mm long, 2.5 mm deep, thinly puberulent, stamens fused, tube sigmoid; anther 0.5 mm.

Distribution.

Sierra Leone, Ivory Coast, Nigeria, Central African Republic, Ethiopia, Sudan, South Sudan, Tanzania, Mozambique, Malawi, Zambia, Angola.

Habitat and ecology.

Rainforest, savannah, dry woodland, dry evergreen forest, fallow fields, ruderal, disturbed ground, rock outcrops, mostly in shady places, occasionally on copper-rich or saline soil; 300–1750 m elev.

Additional specimens.

DR. Congo, Bas-Congo, Kimbuba, 27 Oct 1958, Pauwels 386 ( BR); Kimbidi, 21 Apr 59, L. Pauwels 2536 ( BR); Kasai, Lisha, 28 Apr 1888, F. Hens C 6 ( Z, marked as “ holotype ” in error); Kapanga, 1934, F. Overlaet 1202 ( BR); Thielen Saint-Jacques, H. Vanderyst 21575 ( BR); Bas-Katanga, Tshikamba près Mutombo-Mukulu, Jun 1931, P. Quarré 2512 ( BR); Kamina, 11 Mar 1959, S. Risopoulos 871 ( BR); Kiala, Dec 1954, Thiébaud 210 B ( BR); Forestier Central, Eala, 28 Nov. 1943, R. Germain 1731 ( BR); Entre Bokuma et Bokatola, Sep 1933, J. Lebrun 1313 ( BR); Yangambi, île Yalututcha II, 18 Aug 1938, J. Louis 10905 ( BR, P, U, US); Route Kisangani-Lubutu, 20 Nov 1982, L. Pauwels 6592 ( BR); Ubangi-Uele, Gatanga, Jan 1936, A. M. De Graer 484 ( BR); Garamba, 13 Oct 1951, H. De Saeger 1438 ( BR); Entre Businga et Banzyville [Mobayi-Mbongo], Jan 1930, J. Lebrun 2009 ( BR); Lac Albert, Kurukwata, 4 Nov 1957, P. Gérard 3586 ( BR); Lacs Edouard et Kivu, Ruzizi, Route Uwira-Mbaraka, km 150, May 1950, Germain 7009 ( BR); Ironga, Mutongo, Gutzwiller 2734 ( BR); Lac Mokoto, 21 Jul 1953, D. van der Ben 634 ( BR); Haut-Katanga, Mwashya, May 1939, H. J. Bredo 2757 ( BR); Upemba, riv. Kenia, 28 Mar 1947, G. F. de Witte 2440 ( BR); Kabiashia, 19 Mar 68, F. Malaisse 5438 ( BR, LSHI); Lubumbashi, Mar 1933, P. Quarré 3159 ( BR); Pweto, chutes de la Kafisia, 18 Apr 1926, W. Robyns 2021 ( BR); Luishia, 3 Apr 1990, Tropmetex 82 ( BR, K, MO, MPN, WAG). Burundi, Lac Nyanza, J. Lewalle 6063 ( BR); Route Bugarama, km 8, 2 Jun 1976, M. Reekmans 5184 ( BR); Kabezi, 9 Apr 1978, M. Reekmans 6892 ( BR, WAG); Bururi, Rumonge, 20 Mar 1981, M. Reekmans 9851 ( BR, WAG).

Sierra Leone, Bumban National Park, 25 Sep 1967, J. K. Morton & S. L. Cole 4920 ( SL, K, GC).

Ivory Coast, Inselberg near Duékoué 6 ° 45 ' N, 7 ° 22 ' W, 25 Oct 1991, S. Porembski 1000 ( B, K).

Nigeria, Jos Plateau, Naraguta, 18 Oct 1957, F. N. Hepper 1076 ( BR, K). Cameroon, about 15 km. NE of Meiganga, 24 Nov 1964, W. J. J. O. de Wilde & B. E. E. de Wilde-Duyfjes 4039 ( BR).

Sudan, near summit of Gebel Lothir, 27 Nov 1930, N. D. Simpson 7605 ( K).

South Sudan, Kajiko north, 29 Oct 1982, P. Kosper 128 ( K). Ethiopia, Wellega Region, ca. 30 km S of Asosa. 9 ° 55 ' N, 34 ° 40 ' E, E. I. Friis et al. 7878 ( AAU, C, K).

Tanzania, Kigoma rural Distr, Gobe Stream Reserve, Kakombe Valley, 04 ° 39 ' 50 " S, 29 ° 37 ' 22 " E, 15 May 1999, P. Gobbo et al. 320 ( K, MO).

Mozambique, Serra Macula, Mercula, Simba Camp, 12 ° 04.5 ' S, 37 ° 38 ' E, 10 Jun 2003, J. S. Golding, J. Timberlake & P. Clarke 32 ( K).

Malawi, St. Kizito Seminary, Mtandere Mission, 14 miles E of main road, 25 Apr 1971, Pawek 4668 ( K, MAL).

Zambia: Choma Distr., Sinazongwe / Choma road, 11.6 km from the junction, 16 ° 52 ' 08 " S, 27 ° 16 ' 23 " E, 10 Mar 1997, B. Luwiika, D. K. Harder, H. H. Schmidt, & N. B. Zimba 608 ( BR, K, MO).

Angola. Lunda Norte, 25 km S of Capaia and 55 km WSW of Lucapa, 8 ° 33 ' 25 " S, 20 ° 15 ' 13 " E, 1 Apr 2013 D. G. Goyder & I. Darbyshire 7175 ( K).

Notes.

1. Coleus heterotrichus has been overlooked by recent floras, being synonymised with C. bojeri . In the C. bojeri complex, it has a most distinctive combination of traits, including long cincinni and stem pubescence of short papilliform hairs and sparse long multicellular hairs; it also tends to have larger leaves with cordate base, but this trait is more variable. Some poorly-grown specimens have short cymes and can be deceptive, for example, T. Kassner 2652 (BR, P), J. Bequaert 3100 (BR), but indumentum is typical.

2. C. heterotrichus is one of the most widespread Coleus species in Central Africa, with a surprisingly broad ecological range, from rainforest to rocky outcrops of Katanga.

3. C. claessensii De Wild. is a morphotype with exceptionally long cincinni. C. quarrei De Wild. is a dwarf form, branching from the base.

4. Coleus eetveldeanus was synonymised with Plectranthus dupuisii (= C. welwitschii ) by Paton et al. (2019); it probably belongs here, differing from typical C. heterotrichus in the shorter pedicels (1–2 mm long); however, underground parts are missing and conclusive placement is not possible.

5. Bracts are occasionally more or less persistent (e. g. M. Micha 349, M. Reekmans 436).

6. Lectotypification of Coleus claessensii De Wild. J. Claessens 741 ( BR [ BR 0000006261863 ]) is selected as the lectotype because it is the most complete specimen. Remaining syntype: A. Sapin s. n. (syntype BR), DR. Congo, Ekuta on the Lua, 1912.

7. Lectotypification of Coleus termetophilus De Wild. The very brief protologue published in 1921 without a Latin diagnosis ( De Wildeman 1921 a) indicates “ Elisabethville (Homblé) ” as the type. A much more extensive protologue, with a Latin diagnosis ( De Wildeman 1921 b), indicated the following syntypes: Homblé 154, Homblé 220, Ringoet 397, Ringoet in Homblé 534 and Kassner 2618. Of all these specimens, only two sheets are identified as Coleus termetophilus in De Wildeman’s handwriting, i. e. [ BR 0000008732170 ] and [Z- 000018897]. The sheet [ BR 0000008732170 ] has two collecting labels, i. e. the original label “ Homblé 220 ” and a posterior label “ Kassner 2618 ”. It comprises two specimens marked “ a ” (right-hand) and “ b ” (left-hand), respectively. The label in the left-hand corner of the sheet bears the following note in De Wildeman’s handwriting: “ a) Coleus termetophilus De Wild. n. sp.; b) Coleus homblei De Wild. ”. The protologue of C. termetophilus (“ pétiole atteignant 6 cm de long, limbe ovale, tronqué à la base ”) corresponds only to the right-hand specimen ( T. Kassner 2618). The other specimen (Homblé 220) is C. homblei De Wild. Another sheet in BR is also labelled “ Homblé 220 ” [ BR 0000017710053 ], with three specimens also corresponding to Coleus homblei De Wild. , clearly not matching the protologue of C. termetophilus . Therefore, Homblé 220 must be excluded from the original materials of C. termetophilus . The right-hand specimen on sheet [ BR 0000008732170 ] corresponds to T. Kassner 2618 and is most likely a duplicate from the gathering Kassner 2618 in Z [Z- 000018897]. In the protologue of C. termetophilus, De Wildeman wrote about T. Kassner 2618: “ ce dernier échantillon provenant de l’herbier de Zürich, mis à notre disposition par le Dr. H. Schinz … ” indicating that De Wildeman had indeed received a duplicate. Another sheet in BR [ BR 0000017710183 ] is also a duplicate of T. Kassner 2618, donated by P, apparently not seen by De Wildeman. Based on this, I designate T. Kassner 2618 (right-hand specimen on sheet [ BR 0000008732170 ) as the lectotype of Coleus termetophilus ; T. Kassner 2618 [Z- 000018897]; [ BR 0000017710183 ] are isolectotypes.

8. New species record for Sierra Leone, Ivory Coast, Nigeria, Central African Republic, Ethiopia, Sudan, South Sudan, Tanzania, Mozambique, Malawi, Zambia and Angola.

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.