Streptocarpus salesianorum Eb.Fisch. & I.Darbysh., 2021

Fischer, Eberhard & Darbyshire, Iain, 2021, Five new species of Streptocarpus (Gesneriaceae) from Katanga, D. R. Congo, Plant Ecology and Evolution 154 (2), pp. 264-280 : 271

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

( figs 6 , 9A ) –

Type: D.R. CONGO – Haut Katanga • Bords rocheux de la Panda ; 1937; E. Hofmann S 1799; holotype: BR [ BR0000013147648 ].

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 ).

Description – Monocarpic acaulescent herb. Unifoliate, lamina almost orbicular, 25–27 × 24.5–26.5 cm, base cordate, margin crenate-dentate, apex obtuse, emarginate, pubescent on upper and lower surface, with 13–16 pairs of lateral nerves, petiolode not exceeding 1 cm long, pubescent. Inflorescences 1–2 per plant, arising from the petiolode, peduncle up to 14–17 cm long, eglandular-pubescent. Pedicels 6–12 mm long, eglandular pubescent, bracts linear, up to 2 × 0.5 mm. Calyx divided to base, lobes lanceolate, 3.5–4 mm long, hairs on calyx eglandular. Corolla pale violet, 20–22 mm long, densely eglandular-pubescent, glabrous within, tube slightly curved, only slightly expanded towards mouth, 18–20 mm long, ± 4 mm in diameter, 5(– 6) mm towards mouth, limb bilabiate, upper lip 3 × 3–4 mm, of two rounded lobes, lower lip 3–4 × 3–4 mm, of 3 rounded lobes, lateral lobe 3 × 3 mm, median lobe 4 × 3–4 mm. Stamens inserted in upper third of corolla tube towards mouth, filaments 4 mm long, glabrous, anthers white, 1.5 mm long, staminodes inserted below stamens, 0.8 mm long. Ovary densely eglandular-pubescent, ovary and style 7 mm long. Capsules 54–65 × 1–1.5 mm, eglandular-pubescent.

Distribution – Endemic to south-eastern D.R. Congo (Haut Katanga), only known from the type locality.

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.

IUCN conservation assessment (preliminary) – Critically Endangered: CR B2ab(iii). Streptocarpus salesianorum is only known from the type locality. The estimated AOO is 4 km 2 (assuming a 4 km 2 grid cell size). The habitat, a gallery forest, is under potential threat of logging. As there is only one locality, and to emphasize the threats to the type locality we prefer to assess it preliminarily as Critically Endangered: CR B2ab(iii).

Additional specimens studied – D.R. CONGO – Haut Katanga • Bords de la Panda; 1937; s.col. S 1640; BR[BR0000013147655 ] • Bords de Panda; Apr. 1942; s.col. 195; BRLU .

Figures

Figure 6 – Streptocarpus salesianorum. A. Habit. B. Inflorescence. C. Corolla. D. Mature capsule. E. Hairs on the ovary. From E.Hofmann S 1799. Illustration by Eberhard Fischer.

Figure 9 – A. Distribution map of Streptocarpus malachiticola, S. bampsii, and S. salesianorum. B. Distribution map of S. schaijesii and S. malaissei. Map created using ArcMap 10.8 (https://www. arcgis.com). © Esri and its licensors, all rights reserved.