Hibiscus fabiana Cheek, 2020

Hibiscus fabiana Cheek View in CoL , sp. nov. — Fig. 1 View Fig , 2 View Fig ; Map 1 View Map 1

Differs from H. rostellatus Guill. & Perr. in that the calyx intercostal areas are glabrous or with a few simple hairs, not densely stellate-hairy; costae with bristle-hairs 1-armed, not 2(–4)-armed; from H. noldeae Baker f. differs in calyx nectar gland absent, not present,leaf blade lobed for (0–)20–33 % of its radius, not 70–90 %. — Type: Cheek 13904 (holo HNG; iso BR,K, MO, P, WAG), Guinea, Guinée Forestière,Beyla Prefecture,Mts Kourandou,Sinko, Bronkedou, N8°53'03" W8°18'27", 1040 m, fl., 28 Oct. 2008.

Etymology. Named as a noun in apposition, in honour of Fabiana Goodman of the Ellis Goodman Family Foundation , the latter is the principle sup- porter of the Royal Botanic Gardens, Kew’s Tropical Important Plant Area (TIPAs) programme in Guinea.

Perennial, slender, scandent herb, to 2 m tall. Stems producing ‘gum’ (possibly mucilage) when cut, reaching 5 m long, inter- nodes 3–5(–12) cm long, 2–4 mm diam, with a densely pubescent longitudinal band of c. 1 mm wide, hairs brown, 0.5(–1) mm long, otherwise stems sparsely hairy. Indument: hairs simple, (1–)1.5–2(–2.5) mm long with scattered, conspicuous retrorse, translucent aculei (0.6–)1–1.5 by c. 0.5 mm, on red keel-like (not globose) bases ( Fig. 1c View Fig ). Stipules narrowly oblong, 6–10 by (0.5–)1–1.5(–2) mm, margins moderately densely hairy, hairs (0.5–) 1–2 mm long ( Fig. 1d View Fig ). Leaves: petioles terete, 3.2–8.5(–9.5) cm long, with indumentum and aculei as that of the stems; blades (4.7–)5.7–7.8(–11) by 3.6–7.9(–10.1) cm, mid-stem leaves shallowly 3(–5)-lobed by a third to a fifth of the radius of the blade, main acumen 0.5–1.5(–2) cm long, base obtuse, broadly rounded or truncate, rarely very shallowly cordate, suborbicular in outline, the lobes triangular, abaxial surface sparsely hairy, hairs white-translucent, 0.5–1 mm long, the primary nerves with aculei as those of the stem but smaller ( Fig. 1b View Fig ), adaxial surface glabrous or with a very few occasional hairs, the margin dentate-serrate, 2–3 teeth per cm, the teeth 1–3 mm long, midrib nectary absent. Flowers 8–9 cm diam when open, yellow with purple centre, axillary, solitary, up to 12 per stem in the most distal axils; pedunclespedicels (1–)1.3–2.3(–5) cm long, articulated c. 5 mm below the epicalyx, indumentum as the stem but lacking the pubescent band. Involucellar bracteoles of the epicalyx (9–)10(–11), ligulate, 11–12(–15) by (0.5–) 1 mm, sparsely simple-hairy, the apex bifurcate, the outer (abaxial) fork patent, elliptic, 3–4 mm long, the inner (adaxial) fork erect, ligulate to filiform, 5–7 mm long ( Fig. 1f View Fig ). Calyx 1.6–2(–2.5) cm long, divided ± to the base, sepals 5, ovate-lanceolate, (0.6–)0.7–0.9(–1) cm wide, apex acute, midrib raised, thickened, c. 0.5 mm wide, lacking nectary, hairs (1–) 2 mm long, thick-based; margins thickened (costae), and with indumentum as midrib, margins and midrib fleshy, red, producing red juice when crushed; intercostal areas glabrous or sometimes with a few sparse hairs ( Fig. 1e View Fig ). Petals 5, bright pale yellow, proximal c. 2.5 cm deep purple, obovate, 6–6.5 by 2.7–3 cm, apex rounded, proximal margins with white silky hairs of c. 0.5 mm long. StaminaI column c. 20 mm long, base united with petals, c. 4.5 mm diam, basal part conical, contracting to 4 – 5 mm from the base to a column 1.9–2 mm wide, drying pale brown, the distal antheriferous part c. 5 mm long, c. 6 mm wide, surface scattered with purple glands of c. 0.05 mm diam, each comprised of 4–5 minute globes; filaments free, 20–30, red, c. 4 mm long; anthers subglobose c. 0.9 mm diam. Style exserted c. 4 mm from the staminal column, drying pale brown; dividing into 5 stylar arms each c. 2 mm long; stigmata capitate, purple, c. 0.8 mm diam, densely hairy, hairs c. 0.1 mm long. Capsules 5-valved, ovoid, 1.8–2 by 0.9–1.3 cm, densely setose, beak 2–3 mm long, glabrous. Seeds subreniform, 3–3.5 by c. 2 by 1.5 mm, matt dark brown, with longitudinal lines and glossy pale brown pectinate scales (not shown in Fig. 1g View Fig ).

Distribution — Guinea (Loma-Man Highlands), Liberia (Mt Nimba) and Sierra Leone (Loma Mtns). Likely to be found in the Guinea Highlands of western Ivory Coast (Mt Nimba).

Habitat & Ecology — Restricted to the transition zone (interface) between submontane forest and bowal grassland (on iron or granite): see Discussion; (500–) 700–1200 m altitude.

Conservation — The new species is only known from eight locations (Simandou North, Simandou South, Mts Kourandou, Mts Tetini, Mts Ziama, Mts Bero, Mts Nimba, Mts Loma). Currently there are threats from open-cast iron-ore mining at North and South Simandou and at Nimba. At the Kourandou Mts small-holder cultivation threatens this species (Cheek pers. obs. 2008), while at the Bero Mts the introduction of Zebu cat- tle to the submontane grassland poses a threat to the ecotone habitat of H. fabiana due to trampling (Cheek pers. obs. 2016). No threats are known currently at the Loma Mts or Ziama. The area of occupancy is calculated as 88 km 2. At most sites only single individuals are known, but the global population is likely to be several hundreds of mature individuals. Using the categories and criteria of IUCN (2012) we assess the conservation status of this species as Vulnerable (VU B2ab(iii)).

Additional specimens and observations. GUINEA, Guinée-Forestière, Haute Guinee, Kerouane Prefecture , Simandou Range North , Kekour Mountain at Kerouane , N8°59'51" W8°55'10", 885 m, sterile, 22 Nov. 2007, B. Tchiengue 3077 ( HNG, K, WAG) GoogleMaps ; Macenta and Beyla Prefectures, Simandou Range South , Pic de Fon ,forest at Whisky 1, plot G3, N8°32'57" W8°53'57", 1150 m, 04 Nov. 2005, B. Tchiengue in plot voucher series P 105 ( HNG) GoogleMaps ; Simandou Range, Pic de Fon , forest plot Y3, adjacent to elephant rock, N8°32'03" W8°54'08", 1380 m, sterile, 7 Nov. 2005, Y.B. Harvey Y87 ( HNG) GoogleMaps ; above Canga East,at start of steeper slope towards Pic de Fon, Whisky 1, N8°32'59" W8°53'59", 1075 m, fruit, 03 July 2006, B. Tchiengue 2686 ( HNG, K) GoogleMaps ; Simandou Range, Pic de Dabatini, au nord du Pic de Fon , N8°33'20" W8°53'22", 1583 m,fruit, 22 Mar.2008, P. K. Haba 172 ( HNG, K, WAG) GoogleMaps ; Simandou Range, Pic de Foko, to the south of Pic de Fon , N8°29'28" W8°53'47", 1200 m, flowers, 21 Mar. 2008, B. Tchiengue 3105 ( HNG, K, WAG) GoogleMaps ; Simandou Range, Oueleba Hill , N8°36'50" W8°53'16", 929 m, sterile, 27 Mar.2008, B. Tchiengue 3166 ( HNG, K) GoogleMaps ; Simandou Range, Oueleba Hill , N8°36'52" W8°53'56", 965 m, flowers, 28 Mar.2008, B. Tchiengue 3175 ( HNG, K, WAG) GoogleMaps ; Simandou Range, Pic de Fon area, forest at the water source for Canga East camp, N8°32'57" W8°53'57", 1150 m, sterile, 04 Nov. 2005, B. Tchiengue P105 ( HNG) GoogleMaps ; foot of Simandou range, east of Pic de Fon, near village Kotila , south of Moribadou and Canga East , N8°32'50" W8°52'30", 700 m, 29 Mar. 2008, Simandou record of presence 5 (Observation) GoogleMaps ; Simandou Range, above Canga East, at start of steeper slope towards Pic de Fon , N8°32'59" W8°53'59", 1075 m, fruit, 03 July 2006, B. Tchiengue 2686 ( HNG, K, WAG) GoogleMaps ; Beyla Prefecture, Mts Kourandou, Seberendou , N8°53'05" W8°18'27", 1037 m, young fruit, 17 Nov. 2007, M. Cheek 13711 ( HNG, K, P, WAG) GoogleMaps ; Mts Kourandou, Sinko, Bronkedou , N8°53'03" W8°18'27", 1040 m, flowers, 28 Oct. 2008, M. Cheek 13904 ( BR, HNG, K, MO, P, WAG) GoogleMaps ; Mts Tetini, Piste entre le village de Tagbedou et le sommet du Mont Ketini dans les Monts Tetini , N8°23'21" W8°23'15", 1080 m, flowers, 07 Dec. 2007, P. K. Haba 118 ( HNG, K, WAG) GoogleMaps ; Macenta Préfecture, Mts Ziama, Mont Katia dans le village de Boo ( Boa ), near Sérédou village Boo , N8°11'29" W9°13'47", 540 m, fruit, 23 Mar. 2012, P. K. Haba 992 ( HNG, K) GoogleMaps ; Nzérékoré Prefecture, Mts Béro , sur la route entre le village Laminata et le Mt Zogana , N8°12'06" W8°38'37", 933 m, flowers, 22 Nov. 2008, P.M. Haba 244 ( HNG, K, WAG) GoogleMaps . – LIBERIA, Mts Nimba, 500 m, flower, 9 Jan. 1965, J.G. Adam 20527 ( K, P n.v., UPS n.v.) ; Mts Nimba, 1300 m, flower, 21 Jan. 1965, J.G. Adam 20702 ( IFAN n.v., K, P n.v., UPS n.v.) . – SIERRA LEONE, Bumbuna, Loma Mts, Camp 2, flower, 20 Nov. 1965, J. K. Morton SL 2680 ( K) .

Note — At Simandou, H. fabiana is sympatric over the same altitudinal range as H. noldeae , but no hybrids have been detected, nor have hybrids been detected with H. rostellatus , which also occurs at Simandou, but only at altitudes below c. 900 m.