Neoschumannia gishwatiensis Eb.Fischer, Killmann & Meve, 2013

Fischer, Eberhard, Killmann, Dorothee & Meve, Ulrich, 2013, Neoschumannia gishwatiensis (Apocynaceae, Asclepiadoideae-Ceropegieae) from Gishwati Forest, Rwanda-a third and new species from a disjunct African genus, Phytotaxa 77 (2), pp. 19-26 : 20-23

Neoschumannia gishwatiensis Eb.Fischer, Killmann & Meve , sp. nov. ( Figs. 1 & 2 )

Ab omnibus speciebus Neoschumanniae adhuc cognitis gemmis obovatis, corolla lobis ellipticis, emeraldis, nitidis, corona gynostegiali partibus extendibus basali discoidis conjunctis differt.

Type:— RWANDA. Northern Province: Gishwati Forest Reserve , 29°21’22”E, 1°49’36”S, 2170 m, 2 October 2009, Fischer 13225 (holotype K!; isotype KOBL!) .

Lianas, climbing up to 5 m high, with above-ground runners up to 2 m long. Latex colorless, roots fibrous. Stems twining when support available, 4–5 mm diam, green, glabrous. Petiole up to 2.3 cm long, adaxially channelled; blades elliptic, 9–11 × 5–7 cm, herbaceous to subcoriaceous, basally rounded, acuminate at apex, green, concolor (abaxial side of leaf slightly paler than adaxial side), glabrous, base of lamina adaxially with 2 colleters, stipules reduced or minute, 0.8–1 mm long, glands ovoid. Inflorescences extra-axillary, solitary, many-flowered with 1–2 flowers open at time, pseudo-umbellate, with flowers all arising at apex of peduncle, lax; pedunculate, peduncles filiform, ca. 4–5 cm long, 1.5 mm diam., glabrous; rachis persistent, cylindrical, thick, straight, with numerous lanceolate bracts; pedicels filiform, ca. 4 cm long, 1 mm wide, glabrous. Flowers pendulous. Flower buds obovoid. Calyx aposepalous, sepals lanceolate, ca. 6 mm long, acute, glabrous. Corolla rotate, ca. 25 mm long, apopetalous, petals narrowly elliptic, 24–28 × 8–9 mm, slightly twisted at base and suddenly narrowed to ca. 0.7 mm width, subacute, abaxially greenish, tinged reddish to brownish, adaxially emerald-green, smooth, brilliant, with whitish, vibratile, clavate trichomes, ca. 2 mm long, on base of petals, otherwise glabrous; petals usually slightly spreading at anthesis. Gynostegial corona a basally fused ring of staminal and interstaminal parts which is extended basally into a completely fused skirt; skirt discoid, spreading, fleshy, white, glabrous; staminal corona lobes lanceolate, ca. 2 mm long, conniventerect, purple with translucent-white apex, laterally and abaxially with simple, thin, spreading hairs, 0.4–0.5 mm long, translucent-white; interstaminal corona lobes deltoid, ca. 2 mm long, ascending-erect with apex slightly recurved, canaliculate, occasionally apically notched, white with purple dots, laterally and abaxially covered with simple, thin, spreading hairs, 0.5-0.6 mm long, translucent-white. Gynostegium with corona atop a column, exposed above corolla, column cylindrical, ca. 1.4 × 1.6 mm, whitish. Anthers subquadrate, erect, thickened. Pollinia erect, obovoid, ca. 0.4 × 0.3 mm; corpusculum ellipsoid, ca. 0.2 mm long, with inconspicuous, ellipsoid-deltoid basal projections, caudicles linear, ca. 0.1 mm long, straight. Style head umbonate. Mericarps paired, pendulous, narrowly oblong, terete, 26–30 cm long, 4–5 mm diam., acute-angled (20–30°), shortly beaked, mottled whitish green, green or dark green, glabrous. Seeds ovate, 11 × ca. 4 mm, brown, wing ca. 1 mm wide; coma ca. 30 mm long, white.

Habitat:—This species was found near the edge of the Gishwati Forest Reserve, in degraded secondary forest dominated by Neoboutonia macrocalyx Pax , Macaranga kilimandscharica Pax , Polyscias fulva (Hiern) Harms , Carapa grandiflora Sprague , Vernonia auriculifera Hiern , and Solanecio mannii (Hook. f.) C.Jeffrey at 2170 m altitude. The Gishwati Forest is a remnant of a once larger montane forest ( Mildbraed 1914) that was mostly destroyed in the 1980’s due to a World Bank project, and converted into pastures. The remaining forest relic was again logged after 1994. However, it still harbors a unique diversity and species new to science were recently discovered (Fischer et al. in prep.). The local fauna is also very rich, and a small population of chimpanzees is still present ( R. Chancelor & A. Rundus, pers. comm.). For a description of the vegetation of the Gishwati Forest, see Fischer & Hinkel (1994).

Conservation Status: — Neoschumannia gishwatiensis is only known from the type locality in the Gishwati Forest Reserve. According to the IUCN criteria ( IUCN 2012) it can be assessed as critically endangered ( CR). However, the species may be more widespread in similar forests of Rwanda (e.g., Nyungwe National Park; Fischer & Killmann 2008), Burundi (Kibira National Park) or the Democratic Republic of Congo (Kahuzi-Biéga National Park; Fischer 1996). It may be overlooked as it is not very conspicuous without flowers and fruits and resembles other apocynaceous lianas. Rwanda has a special responsibility for the conservation of this unique species.

Figures

FIGURE 1. Neoschumannia gishwatiensis. A, detail of habit, showing a pair of leaves with inflorescence; B, inflorescence; C, flower; D, petal; E, sepal; F, gynostegium with base of sepal and petals; G, gynostegial corona, interstaminal corona lobe removed; H, staminal corona lobe; I, base of petal; K, interstaminal corona lobe; L, pair of pollinia, with translators and corpusculum; M, clavate, vibratile corolla hair; N, mericarps. All from Fischer 13225. Drawing by E. Fischer.

FIGURE 2. Neoschumannia gishwatiensis. A, B, details of habit with inflorescence, scale bar 1 cm; C, D, flower, scale bar 1 cm; E, detail of flower with gynostegium, scale bar 5 mm; F, pair of pollinia, with translators and corpusculum, scale bar 0.2 mm; G, gynostegium, scale bar = 2 mm; H, seed, scale bar = 2 cm; I, mericarps, scale bar = 3 cm. All photos taken at the type locality by E. Fischer.