Crepidorhopalon whytei (Skan) Eb.Fisch.

Crepidorhopalon whytei (Skan) Eb.Fisch. View in CoL — Fig. 1a–c View Fig , 2a–c View Fig

Fischer (1989) 444; (1992) 165, t. 85, 86; (1999) 110, pl. 44; (2006) 270, f. 160.25; Darbyshire et al.(2015) 329. — Lindernia whytei Skan in Hemsley & Skan (1906) 340; Malaise (1985) 402; Philcox & Ghazanfar (2008) 70, pro maj.parte; Agnew (2013) 300. — Type: Whyte s.n. (lecto K [K000379658], chosen here), Kenya, 1st and 2nd days’ march from Mumias, fl. 7 fr. 6–7 Dec. 1898. Additional syntypes: Hannington s.n. (K), Tanzania, Msalala, fl. without date [1894]; Scott­Elliot 7225 (K [K000379657]), Kenya, Nandi Country, fl. Dec. 1893 – see note.

Torenia mildbraedii Pilg. View in CoL (in Mildbraed & Pilger 1911:285). — Type: Mildbraed 701 ( B destroyed; lecto K [ K000379666 ], chosen here), Luhondo Valley , fl. 13 Aug. 1907 – see note .

Annual or perennial herb, with procumbent, scrambling, trailing or at most weakly decumbent stems up to 60 cm long or more; stems brittle, markedly 4-angular, winged along the angles, glabrous to sparsely or rarely more densely pale eglandular-pubescent, distal internodes sometimes with scattered (sub)- sessile glands; internodes often long, the leaves widely spaced. Leaves sessile, broadly ovate to suborbicular, 7–31 by 5.5–29 mm, base rounded or shallowly cordate, margin serrulate with 2–8(–10) teeth per margin, these sometimes minute, apex acute or obtuse; primary venation palmate, with 5 or 7 main veins from base; surfaces glabrous except sometimes for short hairs along margin towards base and/or on main veins beneath, rarely pubescent throughout, surfaces also with sunken glands drying brown, most visible on lower surface. Flowers either axillary and solitary or together forming a lax terminal raceme (this depending on size of bracts); bracts either foliaceous throughout or rapidly reducing in size distally, then ovate-acuminate to linear-lanceolate, 1.5–7.5 by 0.6–6(–9.5) mm, margin toothed or entire; bracteoles absent; pedicels 1.2–7.5 mm long, glabrous or with (sub)sessile glands, rarely eglandular-pubescent. Calyx 5–10.5(–14) mm long, lobes linear-lanceolate, somewhat unequal in length, longest lobes 3–7.5(–10.5) mm long, apices divergent to recurved at maturity, each lobe 1-veined and with hyaline margin, external surface glabrous except for short pale eglandular hairs along lobe margins and sometimes extending onto tube, rarely eglandular-pubescent throughout, with or without scattered (sub)sessile glands. Corolla 10.5–24 mm long, lower lip blue or purple with white patches in the mouth, or very rarely individuals within a population pure white ( Napier 5349), external surface glandular-puberulous mainly on tube, upper lip usually with pale eglandular hairs; tube (5.7–) 7–11 mm long, cylindrical but slightly contracted in midpoint and widened at mouth, internal surface with 4 lines of subsessile glands in proximal half; upper lip ovate, 3–6.5 mm long, apex emarginate or rounded, internal surface with numerous minute glands; lower lip 5–12 mm long, 3-lobed, median lobe rounded-obovate, 4–7.5 by 5–7 mm, margins of lobes somewhat irregular, bosses on palate of lower lip with blunt-tipped multicellular hairs. Stamens 4, ventral stamens spurred, spurs clavate, 0.5–1.2 mm long, papillate, filaments above spurred portion 3.8–7 mm long; posterior stamens with filaments 1.1–3 mm long; anthers of the two pairs of stamens adhering, thecae 0.7–1 mm long. Ovary ± 1.4 mm long; style 5.5–9 mm long; stigma fan-shaped and minutely fringed. Capsule narrowly ellipsoid to lanceoloid, brown, ± equal in length to calyx or slightly longer, 7–13 mm long, apex somewhat tapered, surface glabrous; seeds ellipsoid or subquadrangular ± 0.6–0.85 by 0.35–0.5 mm, with longitudinal ridges and furrows and with faint horizontal ribs.

Distribution & Ecology — Crepidorhopalon whytei is widespread in East Africa, extending from southwest Ethiopia and southern-most South Sudan, through Uganda, Kenya, eastern D.R. Congo, Rwanda and Burundi to northern and western Tanzania (Map 1). It occurs in upland marshes, seepage areas, stream and pool margins at 1100–2250 m elevation.

Selected specimens seen. BURUNDI, route Karuzi-Muhinga, étang Nzibariba , fl. & fr. 9 Jan. 1958, Van der Ben 1780 ( BR, K); Mwaro Prov., Mwaro, fl. & fr. 10 Jan. 1968, Lewalle 2685 ( BR, K); Bubanza Prov., route Rwegura- Ndora,fl. 19 Oct. 1976, Reekmans 5438 ( BR, K). – D. R . CONGO, Aru-Mahagi , fl. & fr. Aug. 1931, Lebrun 3728 ( BR, K); Munagana, fl. & fr. 1934, De Witte 1872 ( BR, K); terr. Mahagi, Nioka-La Korda, fl. 2 Dec. 1957, Bamps 78 ( BR, K) . – ETHIOPIA, Kaffa, near Sombo, fl. & fr. 13 Nov. 1960, Mooney 8612 ( K); about 7 km along the road from Jimma to Bonga , fl. & fr. 20 June 1969, J . J. F .E. de Wilde 5267 ( BR, K, M, P, WAG *); Kochi , about 5 km E of Jimma along road to Addis Ababa, fl. & fr. 2 Jan. 1973, Friis et al. 2060 ( K) . – KENYA, South Mt Kenya , between Rupinganzi and Thiba R ., fl. 16 Sept. 1951, Davis 60 ( K); bridge over Gathiba R . below Kamweti Forest Station,fl. 9 Aug.1971, Robertson 1565 ( K); Western Province, Mumias , fl. & imm. fr. 11 May 1979, Bridson 80 ( K) . – RWANDA, Rugezi, terr. Biumba, fl. 7 fr. 6 Oct. 1958, Van der Ben 2349 ( BR, K); Butare Préfecture , Rubona ,centre I . S. A .R., fl. 22 Oct.1974, Troupin 15499 ( BR, K); Butare , domaine de l’I. N . R .S., fl. 9 June 1978, Raynal 20379 ( K, P) . – SOUTH SUDAN, Imatong Mts , between Gilo and Mt Konoro, fl. 18 Nov. 1980, Friis & Vollesen 316 ( K) . – TANZANIA, Bukoba, fl. June 1931, Haarer 2035 ( K); Bukoba,fl. & fr. 18 Jan. 1959, Lind 2373 ( K); Kahama Dist. , fl. 16 June 1975, Kahuranga et al. 2781 ( K) .

Conservation — Crepidorhopalon whytei is a widespread species with an EOO of 854 750 km 2 and is known from numerous localities. It would therefore qualify as of Least Concern under criterion B of IUCN (2012). That said, there are serious threats to its habitats in parts of its range, and the species is rapidly decreasing at least in Rwanda and Burundi. While the species was widespread in swamps around Butare (Central Rwanda, Southern Province, Huye district) between 1984 and 1998, the intensive agricultural land use has led to a major decline of the populations, and the species has now almost disappeared (E. Fischer, pers. obs.). If the same situation is true across the species’ range then it could qualify as threatened under IUCN criterion A.

Notes — Crepidorhopalon whytei is rather variable in flower size and inflorescence form. Plants from the Lake Victoria basin ( Uganda, West Kenya, North Tanzania, e.g., E. & C. Godman 87, BM) have the smallest corollas and generally have more clearly developed racemes as the bracts are ± much-reduced in size in comparison to the proximal leaves. Those from the central Kenyan Highlands (e.g., Davis 60, BM) have the largest corollas and have foliaceous bracts, hence the racemes are leafy and the flowers appear to be axillary. Similar plants to these Kenyan populations are found elsewhere in this species’ range, for example in Ethiopia and along the Albertine Rift. However, there are also populations that are intermediate between the two forms, particularly in Uganda and neighbour- ing regions, and it has not been possible to separate any clear infraspecific taxa on the basis of flower and bract size.

Richards & Arasululu 26150 (K) from the Uruwira-Mpanda road in southwest Tanzania is unusual in having markedly long calyces, 12.5–14 mm long with lobes 8.5–10.5 mm long, compared to typical C. whytei with calyces 5–10.5 mm and lobes 3–7.5 mm long. This plant is otherwise a good match for other material of C. whytei . It would be interesting to see more material from western Tanzania to confirm if this difference is consistent; if so, it might be considered a regional subspecies. Plants of C. whytei are usually subglabrous or sparsely pubescent but occasional more densely pubescent plants are recorded across its range (e.g., Bagshawe 1476a, BM). The corolla usually has conspicuous eglandular hairs on the external surface of the upper lip but these can be absent in some populations, most notably in the isolated Ethiopian populations around Jimma; these plants are otherwise a close match for typical C. whytei .

Skan (in Hemsley & Skan 1906) cited three specimens in the protologue of Lindernia whytei ; Whyte s.n. is here selected from among these as the lectotype as it is an informative specimen and it was Whyte’s collection of this species that led Skan to choose the epithet. The holotype of Torenia mildbraedii is believed to have been destroyed in the bombing of the Berlin Herbarium; the extant duplicate at K comprises a small section of a leafy branch with a flower bud, a terminal branch section with immature leaves and an accompanying illustration of a dissected flower. This specimen is here selected as the lectotype of T. mildbraedii .