Dorstenia marijanmatokii Eb.Fisch. & Killmann, 2015

Fischer, Eberhard & Killmann, Dorothee, 2015, A new species and new records of Dorstenia (Moraceae, Dorstenieae) from Rwanda, East Africa, Phytotaxa 212 (3), pp. 213-220 : 213-216

Dorstenia marijanmatokii Eb.Fisch. & Killmann , sp. nov. ( Figs. 1 , 2 , 4 , Tab. 1)

Type: — RWANDA. Western Province , Nyungwe National Park, Cyamudongo Forest, understorey of montane rainforest, 10 January 2011, alt. 1840 m, Eb. Fischer 14015 (holotype BR!; isotype KOBL!) .

Diagnosis: —The new species differs from Dorstenia nyungwensis ( Tab. 1) in the receptacle which is discoid (flattened to navicular in D. nyungwensis ), the dark purple flowering face 15–30 × 10 mm (blackish-purple and 15–22 × 3–7 mm in D. nyungwensis ), the 3 mm wide light purple margin (1 mm wide and green in D. nyungwensis ), the greenish-purple primary appendages up to 14 mm long (green, 12–21 mm in D. nyungwensis ), the 12–23 purple tinged irregular lateral secondary appendages at each side of 4–6 mm length (10–17 lateral appendages, green, more regular, up to 4 mm long in D. nyungwensis ) and the lower surface of leaves with purple veins and dense tomentose indumentum (entirely green and tomentose mainly on the veins in D. nyungwensis ).

Fleshy herb up to 40 (60) cm tall. Stems non-succulent, rooting at the base, unbranched or sparsely branched, up to 4–10 mm in diameter, densely hairy-tomentose. Leaves spirally arranged, shortly petiolate, petiole up to 8–10 mm long, lamina elliptic to obovate, apex obtuse, margin entire or occasionally with 1–3 coarse teeth in the upper half, base obtuse, 12–13 × 4.5 cm, with 4–6 pairs of lateral veins, upper surface vivid green, shining, subglabrous, lower surface pale green with reticulate purple veins, densely pubescent with short and scattered longer hairs, stipules subulate, curved, 5–10 mm long. Inflorescence solitary or up to 2 per axil, axillary, peduncle 10– 6 mm long, densely pubescent. Receptacle discoid, the young ones navicular, becoming convex, flowering face 15–30 × 10 mm, dark purple, margin 3 mm wide, light purple, primary appendages terminal at upper and lower apex, greenish-purple, up to 14 mm long, secondary appendages lateral, 12–23 at each side, up to 4–6 mm long, broadly triangular, irregular, tinged purple. Staminate flowers spaced, numerous, perianth lobes 3, stamens usually 3. Pistillate flowers spaced, numerous, with one style.

Dorstenia marijanmatokii belongs to Section Lomatophora Hijman (1999: 42) ( Berg & Hijman 1999) which comprises 26 species that are mostly typical components of the African lowland rainforest. Only few taxa, e.g. D. afromontana R.E. Fries (1924: 667) , D. brownii and D. nyungwensis are found in submontane or montane forests, and many species have small to very small areas of distribution ( Berg & Hijman 1999).

Etymology: —Dedicated to Mr. Marijan Matok, born on 28 March in Ulm-Söflingen, Federal Republic of Germany, who kindly supported the work of the authors.

Distribution and ecology:— Dorstenia marijanmatokii is another Albertine Rift endemic ( Plumptre et al. 2007) just known from the type locality in Cyamudongo Forest, an isolated forest patch SW of Nyungwe Forest and also part of Nyungwe National Park. This forest differs floristically from the main forest block of Nyungwe from which it is separated by agricultural landscape. Numerous local endemics like Gastrodia rwandensis Eb. Fisch. & Killmann (2010: 317) ( Cribb et al. 2010), Polystachya bruechertiae Eb.Fisch. et al. ( Fischer et al. 2009: 105), or Disperis natascha-oppeltae Eb. Fisch. et al. ( Fischer et al. 2012: 277) are at present only known from Cyamudongo Forest. Dorstenia marijanmatokii grows in the understorey of near-primary forest dominated by Newtonia buchanani .

Dorstenia nyungwensis Troupin ( Fig. 3 , Tab. 1) is the closest relative of D. marijanmatokii and restricted to the Western slope of Nyungwe National Park. The type locality is situated near Gisakura at Km 107 of the road from Huye (=Butare) to Rusizi (= Cyangugu). Other populations have been observed near Kamiranzovu swamp ( Troupin & Lambinon 1977, Fischer & Killmann 2008). At present four localities are known, but the species has not been recorded for Cyamudongo Forest.

Figures

FIGURE 1. Dorstenia marijanmatokii. A, habit, scale bar 3 cm; B, C, detail of inflorescence with receptacles, scale bar 1 cm; D, detail of lower leaf surface, scale bar 5 mm; E, detail of receptacle with flowers, scale bar 0.25 mm. All photos taken at the type locality by E. Fischer (Eb. Fischer 14015, BR).

FIGURE 2. Dorstenia marijanmatokii. A, receptacle, frontal view; B, receptacle, lateral view, scale bar 1 cm.All photos taken at the type locality by E. Fischer (Eb. Fischer 14015, BR).

FIGURE 3. Dorstenia nyungwensis. A, B, detail of inflorescence with receptacles, scale bar 1 cm; C, detail of receptacle, scale bar 5 mm; D, detail of lower leaf surface, scale bar 1 mm; E, receptacle, scale bar 5 mm.All photos taken in Nyungwe NP, Kamiranzovu swamp by E. Fischer (Eb. Fischer 14026, KOBL).

FIGURE 4. Dorstenia marijanmatokii (left) and D. nyungwensis (right). A, habit, scale bar 5 cm; B, detail of inflorescences with receptacles, scale bar 1 cm.All photos by E. Fischer.