Sunday, September 26, 2021

[Botany • 2021] Streptocarpus malachiticola, S. bampsii, S. malaissei, et al. • Five New Species of Streptocarpus (Gesneriaceae) from Katanga, D.R. Congo


Streptocarpus malachiticola Eb.Fisch. & I.Darbysh.,

in Fischer & Darbyshire, 2021.

Abstract

Background and aims – Five new species of Streptocarpus (Gesneriaceae) are described from D.R. Congo in connection with preparing the family treatment for the Flore d’Afrique centrale.

Methods – Standard herbarium practices were applied.

Key results – Streptocarpus malachiticola sp. nov. is related to S. compressus and S. goetzei while S. bampsii sp. nov., S. malaissei sp. nov., S. salesianorum sp. nov., and S. schaijesii sp. nov. are related to S. michelmorei and S. solenanthus. The differences with these species are discussed and distribution maps for the new taxa are presented. An identification key for all known acaulescent species from D.R. Congo, Rwanda, and Burundi is provided. The conservation status of new species is preliminarily assessed. All taxa are range-restricted in Upper Katanga and the assessments are as follows: S. malachiticola: EN B1+2ab(iii), S. bampsii: CR B2ab(iii), S. malaissei: EN B1+2ab(iii), S. salesianorum: CR B2ab(iii), and S. schaijesii: EN B2ab(iii). Streptocarpus malachiticola is found on metalliferous rocks while the remaining species are either epiphytes in gallery forests (S. bampsii) or occur on humid rocks in gallery forests.

Keywords: central Africa, endemism, new species, Streptocarpus malachiticola, S. bampsii, S. malaissei, S. salesianorum, S. schaijesii, taxonomy


Streptocarpus malachiticola Eb.Fisch. & I.Darbysh.
A, C. Habit. B. Inflorescence. D. Flower.
 
Photographs taken by Julie Lebrun, Biodiversity and Landscape Unit, Gembloux Agro-Bio Tech, University of Liège at Tshilongo, Kabwe (A–B: © Julie Lebrun, all rights reserved) and Michel Schaijes at Tenke (C–D: © Michel Schaijes, all rights reserved).


Streptocarpus malachiticola Eb.Fisch. & I.Darbysh., sp. nov.

Diagnosis – Streptocarpus malachiticola differs from S. goetzei in the glandular-pubescent pedicel with shorter eglandular hairs intermixed, the glandular-pubescent calyx, the smaller corolla with glandular hairs outside, the glandular-pubescent ovary, the bilobed stigma and the distinctly shorter capsule. The upper lip of the corolla bears strongly divaricate lobes, thus also differing from S. goetzei. It differs from S. compressus in the strictly unifoliate habit, the glandular-pubescent calyx, the shorter lower lip of the corolla, the blue-violet corolla with pale-whitish palate, the shape of the upper lobes and the more strongly constricted mouth, the eglandular style and the shorter capsules.

Habitat – Shaded vertical siliceous rock faces, often on metalliferous rocks, e.g. malachite, or rarely on non-mineralized rocks, 1200–1500 m elevation. Malachite is a copper carbonate hydroxide mineral [Cu2CO3(OH)2]. It often results from the weathering of copper ores.

Etymology – Named after the metalliferous rocks which are the preferred habitat.


Streptocarpus bampsii Eb.Fisch. & I.Darbysh., sp. nov.

Diagnosis – The species differs from Streptocarpus solenanthus in the straight and usually shorter corolla tube and the shorter lower lip of the corolla, the darker colouring of the corolla lobes and the longer calyx lobes. The species differs from Streptocarpus michelmorei in the smaller pale lilac corolla lacking a deep violet patch on the palate and behind, the corolla tube being almost straight and not deepened on the lower side at the middle, and the upper and the lower lip being almost equal while in S. michelmoreithe lower lip is distinctly larger. It also differs from S. michelmorei in the distinctly shorter capsule.

Habitat – Epiphyte in gallery forest at foot of waterfalls, 1250 m elevation.

Etymology – Named after Paul Bamps, who made major contributions to the knowledge of the flora of Central Africa, and who collected the type.


Streptocarpus malaissei Eb.Fisch. & I.Darbysh., sp. nov.

Diagnosis – The species differs from Streptocarpus michelmorei in the smaller pale lilac corolla lacking a deep violet patch on the palate and behind, the corolla tube being almost straight and not deepened on the lower side at the middle, and the upper and the lower lips being almost equal while in S. michelmorei the lower lip is distinctly larger. It also differs from S. michelmorei in the distinctly shorter capsule. The species differs from Streptocarpus solenanthusin the straight and usually shorter corolla tube and the shorter lower lip of the corolla. It differs from the morphologically similar Streptocarpusbampsii in the deep violet corolla with pale violet tube, shorter ovary and style and the shorter capsule.

Habitat – Epiphyte or lithophyte on humid rocks in gallery forest or ravine near waterfall, 1450 m elevation.

Etymology – Named after François Malaisse, who made major contributions to the knowledge of the flora of Katanga, and who collected the type.


Streptocarpus salesianorum Eb.Fisch. & I.Darbysh., sp. nov. 

 Diagnosis – Streptocarpus salesianorum differs from all other related species even at first glance by the orbicular leaf with a length/width ratio of ca 1. The flowers are similar to that of S. schaijesii but differ in the much shorter tube and the distinctly shorter upper and lower lips. There is an overall similarity to S. solenanthus but the latter species has a corolla with shorter upper lip and a distinctly longer lower lip and a much more ovate to oblong leaf (7–15 × 4–12 vs 25–27 × 24.5–26.5 cm in S. salesianorum).

Habitat – Humid rocks along stream, ± 1450 m elevation.

Etymology – Named after the Salesian missionaries from Institut Saint François de Sales at Lubumbashi (= Elisabethville) who collected the type specimen.

 
 Streptocarpus schaijesii Eb.Fisch. & I.Darbysh., sp. nov.

Diagnosis – The species differs from Streptocarpus michelmorei in the pale lilac corolla lacking a deep violet patch on the palate and behind, in the corolla tube being only slightly curved and scarcely deepened on the lower side at the middle, and in the distinctly shorter capsule. The species differs from Streptocarpus solenanthus in usually having a shorter corolla tube and in the longer lower lip of the corolla. It differs from Streptocarpusbampsii in the slightly curved and longer corolla tube, the longer corolla lower lip and the longer staminodes.

Habitat – Humid, calcareous rocks in gallery forest or ravine near waterfall, 1200–1650 m elevation.

Etymology – Named after Michel Schaijes, who made major contributions to the knowledge of the flora of Katanga, and who collected the type.


Eberhard Fischer and Iain Darbyshire. 2021. Five New Species of Streptocarpus (Gesneriaceae) from Katanga, D.R. Congo. Plant Ecology and Evolution. 154(2); 264-280. DOI: 10.5091/plecevo.2021.1824