Impatiens gesneroidea Gilg

Fischer, Eberhard, Abrahamczyk, Stefan, Holstein, Norbert & Janssens, Steven B., 2021, Evolution of Impatiens (Balsaminaceae) in the Albertine Rift – The endemic Impatiens purpureoviolacea complex consists of ten species, TAXON 70 (6), pp. 1273-1299 : 1294

Impatiens gesneroidea Gilg in Bot. Jahrb. Syst. 43: 116. 1909 –

Holotype: Rwanda. Rugege Wald ( Rukarara ), mid-Aug 1907, J. Mildbraed 916 (B barcode B 10 0153285 ! ; isotype: B barcode B 10 0153286 ! ).

Description. – Plants erect, stems 40–120 cm long, densely covered with hairs. Leaves herbaceous, densely hairy on both sides, petiole 1.8–2.2 cm long, without extrafloral nectaries, lamina broadly ovate, vivid green on upper and lower surface, hairy on both surfaces, 4.2–5.2 × 4.5–3.5 cm, margin with 16–18 pairs of extrafloral nectaries. Inflorescence with 2 flowers, peduncle up to 2.5 cm long, bracts linear-filiform, 4–6 × 0.5 mm, acute, pedicel 2.4–2.6 cm long. Flowers with greenish bucciniform lower sepal tapering into spur, densely hairy, dorsal petal deep red with greenish crest, lateral united petals deep red, yellow at throat. Lateral sepals green, linear-lanceolate, acute, 6–8 mm long and 1 mm wide at base, tapering towards apex, densely hairy. Lower sepal and spur bucciniform, 16–18 mm long and 11 mm deep, spur not or only slightly swollen at apex, spur broad, 7–9 (10) mm long and 2.5–3 mm in diameter. Dorsal petal cucullate, (6) 8– 9 × 4–5 mm. Lateral united petals deep-red with yellow, 10– 12 mm long, upper lateral petal 5–7 × 5–6 mm, lower lateral petal 5 × 4.5 mm. Ovary glabrous, 4 mm long. Fruit glabrous, 14–16 × 4–6 mm. Figures 3 , 6F,G , 17 .

Ecology. – Montane rainforest, 2000–2750 m.

Distribution. – Democratic Republic of the Congo: Kahuzi-Biéga National Park, Mt. Muhi, Kabobo; Rwanda: Nyungwe National Park; Burundi: Kibira National Park.

Specimens examined. – Democratic Republic of the Congo. Lacs Edouard et Kivu. Montagnes à l’ Ouest du Lac Kivu, Massif du Kahuzi, 1929, Humbert 7754 (BR) ; entre Walikale et Kalehe, Apr 1932, Lebrun 5368 (BR) ; route Bukavu–Walikale ; km 42–43, côté droit, 25 Mar 1960, Petit 154 (BR) ; route Bukavu–Walikale, 3 Feb 1958, Léonard 1442 (BR) ; route Bukavu–Walikale ; km 42–43, côté droit, 25 Mar 1960, Petit 183 (BR) ; Bukavu-Kahuzi km 41, 23 Dec 1971, Bamps 2848 (BR) ; Mont Kahuzi 10 Jul 1972, 2700 m, Ntakiyimana 229 (BR) ; Mt. Kahuzi, pont de la Mugaba, km 28 route Kavumu–Walikale, 8 Jan 1956, Pierlot 1220 (BR) ; Kahuzi, 28 May 1960, 2500 m, Meurillon 934 (BR) ; Mont Kahuzi, 23 May 1960, 2260 m, Petit 275 (BR) ; Mont Biéga (Tshibinda), May 1948, Hendrickx 5134 (BR) ; Marais Musisi, 16 Oct 1958, Léonard 1279 (BR) ; Luemba, Dec 1946, Hendrickx 4376 (BR) ; Mt. Muhi, Jul 1948, Hendrickx 5375 (BR) ; Kabobo Forest, 10 Nov 2012, Kirunda BK1301 (BR) ; Kabobo, 18 Nov 2012, Kirunda BK1313 (BR) . Rwanda. Lacs Edouard et Kivu. Nyungwe National Park. Wisumo, 16 Mar 1973, Troupin 14748 (BR) ; Wisumo, commune Gisovu, centre forestier, 17 Feb 1980, Bridson 410 (BR, K) ; env. de Wisumo, centre forestier suisse, à env. 50 km au S. de Kibuye, 21 Feb 1972, Troupin 14452 (BR) ; Forêt de Rugege, versant sud du Mont Muzimu, 3 Mar 1972, Auquier 2730 (BR) ; vers km 95, route Butare–Cyangugu, 9 May 1973, Nuyt 87 (BR) ; Forêt de Nyungwe, Mont Bigugu, 18 Feb 1971, Bouxin 349 (BR) ; Mont Bigugu, 29 Jul 1974, Auquier 3504 (BR) ; Commune Kivu. Savane de Nyabihu, 3 Aug 1999, Ewango 2167 (BR) ; Commune Kivu. Savane de Nyabihu, 2 Aug 1999, Ewango 2162 (BR) ; Mt. Bigugu, 2750 m, 27 Sep 2011, E. Fischer 11021 (KOBL) . Burundi. Lacs Edouard et Kivu. Ijenda, 6 Aug 1971, Reekmans 837 (BR) ; Bugarama, 22 Dec 1965, Lewalle 98 (BR) ; Muramvya – forêt, Mar 1935, Becquet 903 (BR) ; Bukeye, Mont Teza, 19 Jun 1971, Lewalle 6023 (BR) .

Notes. – Grey-Wilson (1980) lists the type locality erroneously from the eastern Democratic Republic of the Congo (“E. Zaire”). The Rukarara is one of the sources of the Nile and situated in Nyungwe National Park, Rwanda.

Figures

Fig. 3. Distribution map of the two bird-pollinated species from the Impatiens purpureoviolacea complex.

Fig. 6. Seeds of the Impatiens purpureoviolacea complex. A–C, Impatiens ludewigii: A & B, Seed; C, Detail of testa. D & E, Impatiens versicolor: D, Seed; E, Detail of testa. F & G, Impatiens gesneroidea: F, Seed; G, Detail of testa. — Scale bars: A, 600 μm; B, 500 μm; C, 100 μm; D, 400 μm; E, 70 μm; F, 400 μm; G, 100 μm. A–C, Fischer 13912, BG Bonn 37754; D & E, Fischer 13988, BG Bonn 34557; F & G, Fischer 11021, BG Bonn 32578.

Fig. 17. Impatiens gesneroidea. A & C–E, Detail of habit with flower in lateral view; B, Flower, frontal view. — A–E, Fischer 11021, Rwanda, Nyungwe National Park, Mt. Bigugu.