Tylophora mayottae W.D. Stevens, Labat & Barthelat, 2016

Stevens, W. Douglas, Labat, Jean-Noël & Barthelat, Fabien, 2016, Two new species of Apocynaceae, Asclepiadoideae from Mayotte, Candollea 71 (1), pp. 127-134 : 131-132

Tylophora mayottae W.D. Stevens, Labat & Barthelat , spec. nova ( Fig. 3 , 4 ).

Typus: M AYOTTE: Grande Terre , Mamoudzou , réserve forestière de Majimbini , La Convalescence , 5.IX.2001, Barthelat et al. 483 (holo-: P [ P00229464 ]! iso-: BR!, K!, MAO!, MO!) .

Tylophora mayottae W.D. Stevens, Labat & Barthelat is similar to T. coriacea Marais , but with smaller flowers which are rotate and a shorter corolla tube (0.2-0.5 mm) and with guide rails which are shorter (0.15-0.2 mm).

Twining and trailing vine with white latex. Stems rooting at nodes, woody and corky below, with hirsutulous indument present at the nodes and sometimes extending in a continuous line along the internodes; internodes 3-14 cm long. Leaves opposite; blades 6.7-13.5 × 4-8.8 cm, ovate to elliptic, apex acute to acuminate, base obtuse to truncate or shallowly lobed with a sinus up to 7 mm deep, both surfaces glabrous, glossy, succulent, margin thickened, lateral veins 4 to 6, colleters 2 to 10, sometimes raised on a fleshy pad; petioles 0.7-3.4 cm, glabrous or hirsutulous on the upper side. Inflorescence 4.5- 6.0 cm long, with hispidulous indument forming a continuous line on the axis; peduncle 1.7-2.2 cm when in flower, up to 5.3 cm long when in fruit. Flowers borne on pedicels 0.5- 0.6 cm long; bracts 2.2 × 0.3 mm, linear to lanceolate; calyx apparently without colleters, lobes 1.3-1.3 × 0.5 mm, lanceolate, apex acute, glabrous or with a few hairs on midrib and margin; corolla pale pink, glabrous outside, densely white-hispid inside with hairs 0.15 mm long, tube 0.2–0.5 mm, lobes 2-2.5 × 1-1.2 mm, lanceolate with acute apex; corona pale yellow 1.0 mm high, 1.5-1.6 mm in diam., 5-lobed; lobes free, erect, more or less reaching to the base of anthers, apices rounded; c o r p u s c u l u m n a r ro w l y e l l i p s o i d, 0.2 -0.2 2 × 0.0 7 - 0.08 mm, translators 0.09 mm long, pollinia ellipsoid, 0.18-0.2 × 0.14-0.16 mm; ovaries glabrous. Follicles 8.2 × 1.1 cm, narrowly fusiform, glabrous, smooth, green; seeds 10-11 × 5.5-6.5 mm, dark brown, margin 0.8 mm wide, irregularly toothed on distal third, surface smooth, finely hispidulose on both sides; coma 2-2.5 cm long, white.

Distribution, habitat and phenology. – Tylophora mayottae is only known from Mayotte, it has been recorded in sub-humid to humid forest between 200 to 400 m in the Majimbini and Combani forest reserves on Grande Terre and in the coastal forests at Saziley on Grande Terre and at Moya on Petite Terre. It has been recorded in flower in October and November, and in mature fruit in September, but flowering and fruiting probably spans at least from August to December.

Vernacular names and local use. – The new species is known from data recorded by Barthelat & Boullet (2005) or on herbarium labels as “Vahy rountou”, “Vahy rotono be” or “Pamba suisui be” in Shibushi dialect, and “Ouvamba suisui bole” in Shimaore dialect. The plant is used in the preparation of magic potions known as “grigris” (M. M’changama pers. comm.).

Conservation status. – Tylophora mayottae is rare and clearly has a restricted distribution. It is known from only three recent collections from three separate protected areas, and three collections from the XIXth century, two of which have no locality details other than “ Mayotte ”. The preliminary risk of extinction of Tylophora mayottae is therefore assessed as “ Vulnerable” [VU D2] following the IUCN Red List Categories and Criteria (IUCN, 2012). Further information on the extant population is needed to be able to provide a more reliable assessment of the conservation status of the new species.

Notes. – Tylophora mayottae is vegetatively similar to T. coriacea , which is restricted to Mauritius, Reunion and the Seychelles, but differs from it by its smaller flowers which are rotate (vs. subcampanulate), with a shorter corolla tube (0.2-0.5 vs. 1.7-2 mm) and shorter guide rails (0.15-0.2 vs. 0.6-0.8 mm).

In a recent molecular study ( Liede-Schumann et al., 2012), Tylophora and a variety of other tropical genera were placed in synonymy with the north-temperate genus Vincetoxicum Wolf. However the authors are not convinced of the merits of this view, and prefer to maintain the genus Tylophora as distinct until more compelling evidence is available.

Paratypi. – M AYOTTE: Grande Terre , Bandré , Saziley , La Convalescence , 30.IX.2003, Barthelat et al. 1242 ( P); Grande Terre , Bandré , Saziley , La Convalescence , 29.XI.2005, Barthelat et al. 1526 ᵐ); sine loc., Boivin s.n. ( P); sine loc., XI.1850, Boivin 3210 ( K, P); forêt de Combani , 21.X.1884, Humblot 1336 ( K, P) .

Figures

Fig. 3. – Field pictures of the new species Tylophora mayottae W.D. Stevens, Labat & Barthelat. [Photos: F.Barthelat]

Fig. 4. – Tylophora mayottae W.D. Stevens, Labat & Barthelat A. Habit;B. Gynostegium; C. Pollinarium. [Boivin 3210, P] [Drawing: A. Arbeláez]