Impatiens lutzmannii Eb.Fisch., Abrah., Holstein

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 : 1285-1286

Impatiens lutzmannii Eb.Fisch., Abrah., Holstein & S.B.Janssens, sp. nov. –

Holotype: Burundi. Bururi Forest Reserve , 2180 m, 16 Mar 2012, E. Fischer 13002 (BR barcode BR0000014532139 !; isotypes: BONN!, KOBL!) .

Diagnosis. – Impatiens lutzmannii belongs to the group with hairy ovary. It differs from I. purpureoviolacea in the upper margin of the upper lateral petals being straight, while lower margin on top largely overlapping with lower lateral petals, the purple maculae on lateral united petals near throat rather small, spot-like, the beige pubescent fruit, the lanceolate leaf lamina with (25) 27–39 pairs of extrafloral nectaries at margin, and the petiole with 3–7 pairs of extrafloral nectaries.

Description. – Plants ascending to erect, usually densely pubescent on stems and lower surface of young leaves, stems 20–25 cm long. Leaves with 3–18 mm long petiole, (3) 4–7 pairs of extrafloral nectaries, lamina lanceolate, 35–98.5 × 13.5–32.5 mm, margin with (25) 27–39 pairs of extrafloral nectaries. Inflorescence with 2–4 flowers, peduncle 7–21 mm long, pedicel 9–14 mm long. Flowers pink, petal base barely yellow, purple maculae at base small, ± hidden in throat. Lateral sepals (4) 6–8 × 2–2.7 mm. Lower sepal navicular, 8–11 mm long and 4–5.5 mm deep, abruptly constricted into a spiraled, usually filiform spur, spur 8–14.5 mm long. Dorsal petal 7–12.5 × 11.5–13 mm. Lateral united petals up to 28 mm long, upper margin of the upper lateral petals straight, while lower margin on top largely overlapping with lower lateral petals; purple maculae near throat rather small, spot-like, upper lateral petal 10–12 × 5.5–6.5 mm, lower lateral petal 16–21 × 6.5– 9 mm. Ovary beige-pubescent, 4–6 mm long. Fruit beige pubescent 13–15 × 6–7 mm. Figures 2 , 4C,D , 9 , 11F–I .

Ecology. – Montane forest at 2180 m.

Distribution. – Burundi, only known from Bururi Forest Reserve.

Etymology. – Named after Nicola Lutzmann, who first discovered the species.

Figures

Fig. 2. Distribution map of the eight insect-pollinated species of the Impatiens purpureoviolacea complex. Dots indicate species with hairy ovaries, and stars mark species with glabrous ovaries.

Fig. 4. Seeds of the Impatiens purpureoviolacea complex. A & B, Impatiens purpureoviolacea: A, Seed; B, Detail of testa. C & D, Impatiens lutzmannii: C, Seed; D, Detail of testa. E & F, Impatiens urundiensis: E, Seed; F, Detail of testa. — Scale bars: A, 300 μm; B, 60 μm; C, 500 μm; D, 80 μm; E, 500 μm; F, 90 μm. A & B, Fischer 12958, BG Bonn 36240; C & D, Fischer 13002, BG Bonn 33486; E & F, Fischer 13301, BG Bonn 35170.

Fig. 9. Impatiens lutzmannii. A, Habit; B, Flower, frontal view; C & D, Flower, lateral view. — A–D, Fischer 13002, Burundi, Bururi Forest Reserve.

Fig. 11. A–E, Impatiens purpureoviolacea. A, Flower; B, Lower sepal and spur; C, Dorsal petal; D & E, Lateral united petals. F–I, Impatiens lutzmannii. F, Flower; G, Lower sepal and spur; H, Dorsal petal; I, Lateral united petals. J–N, Impatiens urundiensis. J, Flower; K, Petiole, lateral sepals and anthers; L, Lower sepal and spur; M, Dorsal petal; N, Lateral united petals. — Scale bar: 1 cm. A–E, Fischer 13911, Rwanda, Rukarara; F–I, Fischer 13002, Burundi, Kumuyange; J–N, Fischer 13301, Burundi, Kumuyange.