Evolution of Impatiens (Balsaminaceae) in the Albertine Rift – The endemic Impatiens purpureoviolacea complex consists of ten species Author Fischer, Eberhard 0000-0001-7455-9833 Institut für Integrierte Naturwissenschaften – Biologie, Universität Koblenz-Landau, Universitätsstrasse 1, 56070 Koblenz, Germany efischer@uni-koblenz.de Author Abrahamczyk, Stefan 0000-0001-8047-932X Nees Institute for Biodiversity of Plants, University of Bonn, Meckenheimer Allee 170, 53115 Bonn, Germany sabraham@uni-bonn.de Author Holstein, Norbert 0000-0001-9892-0355 Natural History Museum, Cromwell Rd., London SW 7 5 BD, United Kingdom n.holstein@nhm.ac.uk Author Janssens, Steven B. Botanic Garden Meise, Nieuwelaan 38, Meise, 1860, Belgium steven.janssens@plantentuinmeise.be text TAXON 2021 2021-09-06 70 6 1273 1299 http://dx.doi.org/10.1002/tax.12566 journal article 2599 10.1002/tax.12566 495154d8-5ca2-4a89-8b30-574f579034cb 1996-8175 5849572 Impatiens versicolor Eb.Fisch., Abrah., Holstein & S.B. Janssens , sp. nov. Holotype : Rwanda . Western Province , Nyungwe National Park , road 7 km south of Pindura towards Bweyeye , rocks and wet roadsides, 1800– 1900 m , 8 Mar 2013 , E. Fischer 13390 (BR barcode BR0000014532108 !; isotype : BONN ! ). Diagnosis. – Impatiens versicolor belongs to the group with glabrous ovary. It differs from I. ludewigii in the white flowers, with occasionally single pink flowers appearing on the same plant, the dorsal petal divided to less than 1/3 of its length, the plants densely hairy on upper leaf surface, stems and pedicels, later glabrescent, the leaves at margin with 10– 15 pairs of extrafloral nectaries, and the often suberect habit. Description. – Plants erect to suberect or ascending, usually glabrous or only with loose hairs, or sometimes densely hairy on upper leaf surface, stems and pedicels later glabrescent, stems 20–50 cm long. Leaves with 4–8 cm long petiole, petiole with 0–2 (4) pairs of extrafloral nectaries, lamina ovate, acuminate, 35–46 × 21–34 mm, margin with 10–15 pairs of extrafloral nectaries. Inflorescence with (1) 2 flowers, peduncle 5.5– 16.5 mm long, pedicel 11–18 mm long. Flowers white, petal base barely yellow, purple maculae at base large, occasionally single pink flowers appearing on the same plant. Lateral sepals 4.5–6.5 × 1–2 mm. Lower sepal navicular, 7–9 mm long and 3– 4.5 mm deep, abruptly constricted into a spiraled, usually filiform spur, 13–19 mm long. Dorsal petal divided to less than 1/3 of its length, 7–11 × 10.5–16.5 mm. Lateral united petals up to 23 mm long, upper lateral united petals 10–18 × 5–7.5 mm, not overlapping lower lateral united petals, base of upper lateral petal with dark pink or red and yellow maculae, lower lateral petal 13–19.5 × 5–7.5 mm. Ovary glabrous, 4– 5 mm long. Fruit glabrous, 13 × 6 mm. Figures 2 , 6D–E , 15 . Fig. 13. A–D , Impatiens elwiraurzulae . A & C , Flower, frontal view; B , Flower, lateral view; D , Flower showing only slightly coiled spur. E , Impatiens lotteri , detail of habit with flower. — A–D, Dumbo & Dumbo s.n ., Democratic Republic of the Congo, Mulolo; E, Lotter 1542 , Democratic Republic of the Congo, Ulindi River (Photo: M.C. Lotter). Ecology. – Wet rocks and roadbanks in montane rainforest, 1800–1900 m. Distribution. – Rwanda, only known from Nyungwe National Park, only recorded in a valley south of Pindura towards Bweyeye. Fig. 14. Impatiens elwiraurzulae . A , Leaf, upper surface; B , Leaf, lower surface; C & D , Inflorescence; E , Flower; F , Lower sepal with spur; G , Dorsal petal; H & I , Lateral united petals; J , Bracts, pedicel, lateral sepals and anthers. — Scale bar: 1 cm. A–J, Dumbo & Dumbo s.n ., Democratic Republic of the Congo, Mulolo. Etymology. – Named after the occasional but regular colour change of single flowers from white to pink.