Clerodendrum fuscum Gürke (1893: 175)

Meerts, Pierre, 2023, The genus Clerodendrum (Lamiaceae) in the flora of Central Africa (D. R. Congo, Rwanda, Burundi), Phytotaxa 594 (1), pp. 1-42 : 18-19

12. Clerodendrum fuscum Gürke (1893: 175) ; Durand & Schinz (1896: 223); Baker (1900: 304); De Wildeman (1903: 72; 1910b: 255; 1910a: 402); Durand & Durand (1909: 438); Thomas (1936: 61); Robyns (1947: 143); Malaise (1985: 274); Moldenke (1986c: 475); Verdcourt (1992: 99); Lebrun & Stork (1997: 511); Fischer & Killmann (2008: 232); Bloesch et al. (2009: 626); Lejoly et al. (2010: 294), Vande weghe et al. (2016: 743); Pollard (2022: 28).

Type:— UGANDA, Kigezi District , Echuya Forest Reserve, 7820 ft., 8 August 1960, Paulo 671 (neotype designated here: K (without barcode)!; iso-: BR0000016597464!) .

= Clerodendrum fuscum var. attenuatum Moldenke (1953a: 176 ; 1986c: 478). Type:—D.R. CONGO. Eala, 7 July 1932, Corbisier-Baland 1609 (holotype: BR0000008976161!, iso-: BR0000008976123!).

= Clerodendrum macrocalyx De Wildeman (1920b: 172 ; 1922: 264). Types:—D.R. CONGO. Avakubi, 20 January 1914, Bequaert 2031 (syntype:BR0000008976109!,BR0000008976093!); Masisi,Walikale, 4 January1915, Bequaert 6492 (syntype:BR0000008976086!; NY 00137361); Bomili, 26 December 1913, Bequaert 1637 (syntype: BR0000008971692!, iso-: BR0000008971074!), nom. illeg. non Lam (1919: 293).

= Clerodendrum grandicalyx Bruce (1934: 306) ; Thomas (1936: 61). Type:— UGANDA. Shores of lake Mutanda, 10 January 1933, Rogers 319 (holotype: BM000798633; iso-: K000192888).

Shrub, sarmentose shrub, or liana 1–8 m high. Stem pubescent with purplish-brown articulated hairs 0.4–1.2 mm; persistent petiole base generally lacking, more rarely present (1–4 mm). Leaf: petiole 0.2–6.0 cm, markedly decreasing in length towards apex, pubescent as the stem; lamina ovate to suborbicular, 7–15(–20) × 5–13(–15.5) cm, base cordate, apex obtuse to acute, or abruptly contracted in a short acumen, mucronate, 3–4 veins on either side, reticulum prominent on lower surface, more or less pubescent on both surfaces, more densely so on lower surface of veins, slightly roughish, margin entire, ciliate. Inflorescence comprised of axillary corymbiform dichasial cymes 3–12 cm wide on the 1–3(–4) uppermost nodes, spaced 5–10 cm, the lowermost pair subtended by subsessile leaf-like bracts, broadly ovate, 3–6 × 3– 6 cm, cordate, somewhat clasping, obtuse and abruptly contracted into a short point; peduncle of the cymes 3–10 cm, purplish-brown pubescent to tomentose. Flower: pedicel 5–15(–30) mm, shortly pubescent, bracteoles filiform; calyx (9–)12–25(–28) mm, tube obconical, 2 mm long, greenish, abruptly dilated into the campanulate, gibbous, pentagonal limb, cream to yellow, sometimes turning rose to violaceous, 8–23 mm long, 5-lobed, shortly fused over 2–7 mm, triangular to ovate-triangular, (8–)11–22 × (3–)5–9(–10) mm, acute to long attenuate, shortly pubescent (brown hairs), occasionally subglabrous; corolla: tube 20–25 mm, glandular-pubescent, lobes 6–10 mm long, cream, one or several lobes red-notched near base or entirely red; stamens: greenish filament, exserted 20–25(–40) mm, anther ca. 2 mm long. Fruit obovoid, 4-lobed, ca. 12 × 15 mm, black, shiny, seed blackish, aril abaxial, oblong, ruminate, orange.

Distribution in Central Africa:—D.R. Congo, Rwanda, Burundi.

Distribution elsewhere:— Gabon, Uganda, Republic of Congo, Angola.

Habitat:—Rainforest (e.g. Scorodophleetum zenkeri; Brachystegletum laurentii), montane forest, secondary forest and shrub savannah with Hymenocardia ulmoides , dry ́bateke» forest on kalaharian sand, mountain scrub with Ericaceae and ferns; 300–2930 m.

Selection of representative specimens:—D.R. CONGO. Mayombe: Bata-Ziala, mission Tshela, 6 August 1975, Breyne 2770 (BR!); Mt. Kionzo, 29 July 1948, Donis 1949 (BR!). Bas-Congo: Tampa, 22 June 1952, Callens 3651 (BR!); Kimuenza, 25 July 1957, Robyns 4393 (BR!). Kasaï: Mapangu, 25 July 1978, Dumont 244 (BR!); Kahemba, route vers l’Angola, Duvigneaud 956C1 (BRLU!); Port Francqui [Ilebo], May 1938, Gillardin 373 (BR!). Forestier Central: Ituri, Mongbwalu, 22 January 2011, Bytebier 3243 (BR!); Lac Tumba, December 1920, Goossens 1554 (BR!); Yangambi. Le long de la rivière Lusambila, 29 July 1958, A. Léonard 1029 (BR!); Yangambi, 23 December 1935, Louis 876 (BR!); Territ. Mambasa, Ituri Forest , Lenda, 25 January 2001, Mokbondo, Bujo & Madidi 377 (BR!, EPU, K, MO, WAG); Territ. Kalehe, vers km 110 route Kavumu-Walikale, Irangi, Troupin 6299 (BR!, US). Ubangui-Uele: s.l., 1906, Seret 460 (BR!). Lac Albert: Réserve de Djugu , 21 March 1952, Smeyers 191 (BR!). Lacs Edouard et Kivu: env. Mt. Nguli , 17 February 1956, de Wilde 643 (BR!); Beni, Entre Kihanga et Mabuye, February 1939, Gille 193 (BR!); Plaine au sud du Lac Edouard, May-June 1929, Humbert 8682 ( P).— RWANDA. Lacs Edouard et Kivu: Préfecture de Cyangugu , Commune de Kirambo , Forêt de Uwinka , 7 April 2000, Ewango 2244 (BR!); Rangiro, 12 June 1978, Raynal 20488 ( P); Env. Uwinka, Territ Shangugu, 12 August 1960, Troupin 12713 (BR!). Rwanda-Burundi: Forêt de Rugege (Cyangugu), au km 103 de la route Butare-Cyangugu, 25 July 1974, Auquier 3433 (BR!); Forêt de Nyungwe , plantation de Gisakura, 12 March 1971, Bouxin 440 (BR!).— BURUNDI. Lacs Edouard et Kivu: Bubanza, route de Butara, 23 March 1966, Lewalle 604 (BR!, MO); Territ. Bubanza, Mabaye, Lua, 22 June 1969, Lewalle 3776 (BR!).

Neotypification of Clerodendrum fuscum Gürke. The lectotype designated by Thomas (1936) i.e., UGANDA. West-Mpororo, Berge von Kajonsa [Kayonza], 1600 m, 28 January 1892, Stuhlmann 3061 (B, not seen) has been lost, as well as the remaining syntypes (Pogge 335, Stuhlmann 3096). The species is variable across its range (see note hereafter); therefore, it is wise to select the neotype from the same region as the lectotype. The neotype (Paulo 671) matches the protologue and was cited by Verdcourt (1992).

Notes:—1. Length and shape of calyx lobes are very variable; morphs with narrow (3–4 mm wide), long attenuate calyx lobes have been described as var. attenuatum Moldenke ; morphs with very long calyx lobes (20–25 mm) have been described as C. macrocalyx De Wild. These forms are striking; however, variation is continuous and these taxa are not recognized here.

2. The indumentum of lower leaf surface is very variable; from very shortly pubescent with the hairs concentrated on veins (the most widespread condition), to appressed pubescent with long thin hairs (1 mm) over the whole surface (e.g. Bamps 429, Louis 5839, 10044, 12781, 13065).