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Marsdenia mayottae W.D. Stevens, Labat & Barthelat, spec. nova (Fig. 1, 2). Typus: M AYOTTE: Grande Terre, Bandré, Rassi Abambo, 9.II.2001, Barthelat, M’Changama & Ali Sifari 295 (holo: P [P00229277]!; iso: G!, K!, MAO!, MO!, P [P00282507]!). Marsdenia mayottae W.D. Stevens, Labat & Barthelat is most similar to M. vohiborensis Choux, but differs from this species by its umbonate style apex completely covered by the terminal anther appendages and the absence or near absence of a corona. Shrub or twining vine, woody but apparently not corky, underground parts unknown, stems densely appressedpuberulent, sparsely lenticellate, internodes 1-6 cm; latex white. Leaves opposite; blades 6.5-11.1 × 4-9.2 cm, ovate to elliptic, glabrous or puberulent on veins below; apex acuminate to attenuate; base truncate to shallowly lobate, its sinus up to 5 mm deep, lateral veins 4 to 6, colleters 10 to 24; petiole 2.4-5.5 cm, sparsely puberulent. Inflorescences solitary, paniculate with 2 to 6 congested-racemose, appressedpuberulent branches; peduncle (3) 10-48 mm; fertile axes up to 3 cm long, more or less covered with pedicel scars. Flowers borne on pedicels 4–9 mm long; bracts numerous and conspicuous, 1.5-10 × 0.6-4 mm, elliptic to spathulate, sometimes leaf-like; calyx with 1 colleter below each sinus within, lobes elliptic to ovate with round tips, unequal, 3-4 × 1.7-2 mm, sparsely puberulent along axis abaxially, not ciliolate, green; corolla shallowly campanulate, dull yellow, without calli, barbate in distal half of tube and proximal half or more of each lobe adaxially, glabrous abaxially, tube 1.7-2.3 mm, lobes elliptic with tip rounded, 2.2-3 × 1.6- 1.7 mm, patent; corona lobes absent or if present reduced to a fleshy tooth adnate to base of anther, deltate, up to 0.4 mm long, 0.2 mm wide at base; gynostegium nearly sessile, guide rails 0.7 mm long, slightly salient at base; anthers trapezoidal, nearly rectangular, 0.8-1 × 0.8-1 mm, terminal appendages 0.6 × 0.6 mm, elliptic to ovate, translucent, corpusculum ellipsoid to subsagittoid, 0.19-0.28 × 0.08-0.13 mm, translators flat, 0.19-0.25 × ca. 0.05 mm, pollinia ellipsoid to obovoid, 0.39-0.43 × 0.24-0.3 mm; style apex umbonate, 1.4-1.5 mm wide at base. Follicles narrowly ovoid with asymmetrical base, 7.5-9.5 × 2.5-3.5 cm, smooth, glabrous, follicle wall 5-7 mm thick; seeds elliptic, 8-11 × 5-7 mm, dark grey-brown with red-brown mottling, margin 0.6-0.7 mm wide, distally entire or inconspicuously crenulate, surface smooth, coma 3.5-4 cm long, white. Distribution, habitat and phenology. – Marsdenia mayottae is only known from Mayotte, where it can be found at low elevations (less than 10 m a.s.l.) in littoral forest growing with Thespesia populnea (L.) Sol. ex Corrêa, Xylocarpus granatum Koenig, Mimusops comorensis Engl., Maytenus undata (Thunb.) Blakelock and Calophyllum inophyllum L. It is also found on coastal squeletic soils on basaltic rock or in dry littoral scrubland with Grewia picta Baill., G. triflora (Bojer) Walp., Guettarda speciosa L. and Maytenus undata. In addition, it can be found also on calcareous sand soil with Talipariti tiliaceum (L.) Fryxell. The new species is very rarely present also in dry lowland forest on other substrates at up to 100 m. Marsdenia mayottae has been recorded in flower from November to January and in fruit in May and June. Vernacular names and local use. – The following vernacular names in Shibushi have been recorded for M. mayottae by Barthelat & Boullet (2005) or on herbarium labels: “Pamba suisui be” or “Pamba suisui famakitrano”, “Macarangana vahi”, “Vahy rotono”, “Vahy maro” and “Kidoro voalavo”. The plants are used in the preparation of magic potions known as “grigris” (M. M’changama, pers. comm.). Conservation status. – Marsdenia mayottae is only known from highly threatened littoral and lowland dry forests on Mayotte, and its population, as currently known, is highly fragmented. It is only known from five locations despite intensive inventories in the last decades. Thus, its preliminary risk of extinction can be assessed as “Endangered” [EN B2ab(iii)] following the IUCN Red List Categories and Criteria (IUCN, 2012). Notes. – This species shares a dense, bracteate inflorescence with M. vohiborensis Choux from the central plateau of Madagascar. However, M. vohiborensis has a long-exserted style apex while M. mayottae has an umbonate style apex completely covered by the terminal anther appendages. The absence or near absence of a corona in M. mayottae is unique among the species of Marsdenia of Madagascar and the Comoros, and rare in the genus. Paratypi. – M AYOTTE: Grande Terre, Saziley, 17.I.2001, Barthelat & Ali Sifari 233 (G, K, MAO, MO, P); Petite Terre, Labattoir, Plage de Moya, 15.I.2002, Barthelat & Ali Sifari 694 (K, MAO, MO, P); ibid. loc., 15.I.2002, Barthelat & Ali Sifari 699 (MAO, MO, P); Grande Terre, Mliha, Mtsumbatsu, 20.XII.2001, Barthelat et al. 625 (MAO, MO, P); sommet du Bouzi, X.1850, Boivin s.n. (P); Rassi Maoussi, 17.V.1999, Mas 176 (P); Sohoa, 28.VI.1997, Pascal 942 (G, MO, P).

Tylophora mayottae W.D. Stevens, Labat & Barthelat, spec. nova (Fig. 3, 4). Typus: M AYOTTE: Grande Terre, Mamoudzou, r��serve foresti��re 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�����, Saziley, La Convalescence, 30.IX.2003, Barthelat et al. 1242 (P); Grande Terre, Bandr�����, Saziley, La Convalescence, 29.XI.2005, Barthelat et al. 1526 ���); sine loc., Boivin s.n. (P); sine loc., XI.1850, Boivin 3210 (K, P); for��t de Combani, 21.X.1884, Humblot 1336 (K, P)., Published as part of Stevens, W. Douglas, Labat, Jean-No��l & Barthelat, Fabien, 2016, Two new species of Apocynaceae, Asclepiadoideae from Mayotte, pp. 127-134 in Candollea 71 (1) on pages 131-132, DOI: 10.15553/c2016v711a15, http://zenodo.org/record/5721433, {"references":["Barthelat, F. & V. Boullet (2005). Index de la flore vasculaire de Mayotte - version 2005 - 1. In: Rolland, R., V. Boullet & J. - P. Quod (ed.), Mayotte: Biodiversite et Evaluation Patrimoniale: 115 - 187. DAF de Mayotte & CBN Mascarin.","Liede-Schumann, S., H. Kong, U. Meve & M. Thiv (2012). Vincetoxicum and Tylophora (Apocynaceae: Asclepiadoideae: Asclepiadeae) - two sides of the same medal: Independent shifts from tropical to temperate habitats. Taxon 61: 803 - 825."]}

Threatened flora of Mayotte : heritage value and challenges for conservation. — This paper deals with the natural history and the flora of Mayotte by presenting some of its characteristics and providing an assessment of its conservation status. Mayotte is a French islands group belonging to the Comoros archipelago (Indian Ocean), located between Madagascar and East Africa. Its geological history, its geographical position and multiple human influences have shaped some remarkable landscapes composed by unique ecosystems and habitats, with an extraordinary biodiversity for a small territory. Since the first inhabitants, via the colonial centuries to the contemporary era, natural vegetation is restricted to the bare minimum but nevertheless it houses most of the plant biodiversity in Mayotte. As sanctuaries these small natural areas are unfortunately still poorly known and highly threatened. The flora of Mayotte was not well studied in the past because the naturalists’ attention was probably drawn by Madagascar. Most of the discoveries were made during the two main periods of investigation that took place during the second half of the nineteenth century and the late twentieth to date. The vascular flora of Mayotte is composed by 681 species that have been recently evaluated by using the categories and criteria of the IUCN Red List. To illustrate the need and urgency to ensure the conservation of this unique heritage, a “Top fourteen” of the critically endangered species is proposed and suggestions for conservation measures are discussed., Cet article traite de l’histoire naturelle et de la flore de Mayotte en présentant quelques unes de ses caractéristiques et en proposant un état des connaissances de son statut de conservation. Mayotte est un groupe d’îles françaises de l’archipel des Comores situé dans l’océan Indien entre Madagascar et l’Afrique de l’Est. Son histoire géologique, sa position géographique et les influences humaines ont façonné des paysages singuliers composés de milieux naturels aujourd’hui relictuels qui contiennent une grande diversité biologique pour un territoire de cette taille. Des premiers habitants à la démographie exponentielle contemporaine, en passant par l’agriculture rentière coloniale, la végétation naturelle n’occupe plus aujourd’hui qu’une portion congrue de Mayotte mais abrite l’essentiel de la biodiversité végétale mahoraise. Ces espaces naturels qui constituent assurément des sanctuaires sont malheureusement encore méconnus et grandement menacés. L’attention des naturalistes ayant porté sur Madagascar dans le passé, la flore de Mayotte est longtemps restée peu étudiée. L’essentiel des découvertes a été fait lors des deux principales périodes d’investigation qui ont eu lieu pendant la deuxième moitié du 19ème siècle et de la fin du 20ème à ce jour. Sa flore originale est représentée par 681 espèces de plantes vasculaires qui ont été récemment évaluées selon les catégories et les critères de la Liste Rouge de l’UICN. Pour illustrer la nécessité et l’urgence de garantir la pérennité de ce patrimoine unique, une liste des 14 espèces en danger critique d’extinction est proposée et des suggestions d’actions de conservation sont discutées., Barthelat Fabien,Viscardi Guillaume. Flore menacée de l’île de Mayotte : importance patrimoniale et enjeux de conservation. In: Revue d'Écologie (La Terre et La Vie), supplément n°11, 2012. Conférence sur la Conservation de la flore menacée de l’Outre-mer français. pp. 15-27.

Wilkin, Paul, Hladik, Annette, Labat, Jean-Noël, Barthelat, Fabien (2007): A new edible yam (Dioscorea L.) species endemic to Mayotte, new data on D. comorensis R.Knuth and a key to the yams of the Comoro Archipelago. Adansonia (3) 29 (2): 215-228, DOI: http://doi.org/10.5281/zenodo.5187427, {"references":["BURKILL I. H. 1960. - The organography and the evolution of the Dioscoreaceae, the family of the yams. Journal of the Linnean Society (Botany) 56: 319-412.","BURKILL I. H. & PERRIER DE LA BATHIE H. 1950. - Dioscoreacees, in HUMBERT H. (ed.), Flore de Madagascar et des Comores. Museum national d'Histoire naturelle, Paris, 78 p.","FOSBERG F. R. & RENVOIZE S. A. 1980. - The flora of Aldabra and neighbouring islands. Kew Bulletin Additional Series 7, HMSO, London: 1-358.","HAIGH A., WILKIN P. & RAKOTONASOLO F. 2005. - A new species of Dioscorea L. (Dioscoreaceae) from western Madagascar and its distribution and conservation status. Kew Bulletin 60: 273-281.","IUCN 2001. - IUCN Red List Categories and Criteria: Version 3.1. IUCN Species Survival Commission, Gland, Switzerland; Cambridge, UK, ii + 30 p.","MARAIS W. 1978. - Dioscoreacees, in BOSSER J., CADEL T. & JULIEN H. R. (eds), Flore des Mascareignes : la Reunion, Maurice, Rodrigues. Fam. 177 Iridacees to 188 Joncacees. The Sugar Industry Reseach Institute, Mauritius; Office de la Recherche scientifique et technique d'Outre-Mer, Paris; Royal Botanic Gardens, Kew: 1-5.","WEBER O., WILKIN P. & RAKOTONASOLO F. 2005. - A new species of edible yam (Dioscorea L.) from western Madagascar. Kew Bulletin 60: 283-291.","WEBERLING F. 1989. - Morphology of Flowers and Inflorescences. Cambridge University Press, Cambridge, 405 p.","WILKIN P., RAKOTONASOLO F., SCHOLS P. & FURNESS C. A. 2002. - A new species of Dioscorea (Dioscoreaceae) from Western Madagascar and its pollen morphology. Kew Bulletin 57: 901-909.","WILKIN P., SCHOLS P., CHASE M. W., CHAYAMARIT K., FURNESS C. A., HUYSMANS S., RAKOTONASOLO F., SMETS E. & THAPYAI C. 2005. - A plastid gene phylogeny of the yam genus, Dioscorea: roots, fruits and Madagascar. Systematic Botany 30: 736-749."]}

Wilkin, Paul, Hladik, Annette, Labat, Jean-Noël, Barthelat, Fabien (2007): A new edible yam (Dioscorea L.) species endemic to Mayotte, new data on D. comorensis R.Knuth and a key to the yams of the Comoro Archipelago. Adansonia (3) 29 (2): 215-228, DOI: http://doi.org/10.5281/zenodo.5187427