Xyris marojejyensis Lock, Rakoton., Callm. & Phillipson, 2014

Rakotonirina, Nivo, Callmander, Martin W., Phillipson, Peter B. & Lock, J. Michael, 2014, Two new species of Xyris L. (Xyridaceae) endemic to Madagascar with a key to the Malagasy species, Candollea 69 (2), pp. 171-178 : 173

Xyris marojejyensis Lock, Rakoton., Callm. & Phillipson , spec. nova ( Fig. 1 ).

Typus: MADAGASCAR. Prov. Antsiranana: Sommet oriental du massif de Marojejy (NE) à l’W de la haute Manantenina, affluent de la Lokoho, [14°25’48”S 49°43’ 48”E], 1850-2137 m, fl., 17-20.XII.1948, Humbert & Capuron 22770 (holo-: P [ P00730642 ]!; iso-: BR!, G [ G00406221 ]!, K!, MO!, P [ P00730640 ]!, TAN!).

Haec species a congeneris madagascariensibus caule robusto, foliis ca. 8 mm latis, inflorescentia nitida in vetustate non elongata atque bractis fertilibus grandibus (ca. 10 × 8 mm) distinguitur.

Large perennial herb to 1 m. Leaves up to 35 × 0.6-0.8 cm; sheaths 5-6 cm long, weakly ridged; ligule c. 2 mm long, rounded, brown-hyaline; lamina up to 35 cm long and 0.8 cm wide, flat, thickened and coriaceous, smooth, slightly asymmetric and blunt at the apex, margins thickened. Scapes terete up to 70 cm tall and 3 mm in diam., with a single deflexedpubescent longitudinal ridge. Inflorescences broadly ellipsoid, c. 10 mm in diam. Lowest pair of sterile bracts broadly ovate to orbicular, c. 4 × 4 mm, glossy brown, rounded at the apex; upper sterile bracts, 4-6, similar but larger; fertile bracts, 6-8, broadly ovate-elliptic, c. 10 × 8 mm, glossy brown, slightly darker towards the rounded or retuse-mucronate apex, lacking a dorsal mark, concave, smooth. Flower lateral sepals slightly curved, strongly keeled c. 8 × 0.6 mm, very pale brown, much darker on the keel, the keel spinose-pubescent, particularly towards the middle. Petals suborbicular, c. 1 cm in diam., yellow. Staminodia not present. Stamens 3, alternating with the petals, epipetalous; anthers sessile, linearc. 4 x 1 mm, with a longitudinal dehiscence. Ovary obovate, c. 5.5 × 1.9 mm, brown. Style 3-branched, the branches capitate at the apex. Young fruit ovoid, 0.5 × 0.2 mm, brown, glabrous. Seeds ovoid 0.1 × 0.03 mm, brown, glabrous.

Distribution and ecology. – Xyris marojejyensis is known only from between 1300 to 2100 m in the Marojejy massif in north-eastern Madagascar, growing in ericoid shrubland on substrates derived from gneiss and quartzite ( Fig. 2 ).

Notes. – The large size of its leaves and bracts, and the shape of its scapes and flowers easily distinguished X. marojejyensis from its Malagasy congeners. The new species can be distinguished from the other larger species occurring in Madagascar, X. baronii and X. congensis , most easily in the case of the former by the shape of its scapes (terete vs. ovoidfusiform in X. baronii ) and dimensions of its bracts (c. 10 × 8 vs. 4-5 × 0.5 mm in X. baronii ), and from the latter by the broader leaves (0.6-0.8 vs. 0.15-0.3 cm in X. congensis ) and corolla (1 cm. in diam. vs. 0.35 cm in diam. in X. congensis ).

Conservation status. – With an EOO of 398 km ², and an AOO of 63 km ² and three known subpopulations all occurring in a Protected Area (Marojejy), X. marojejyensis is assigned a preliminary status of Least Concern [LC] due to its distribution at high elevation in a non-threatened habitat.

Paratypi. – MADAGASCAR. Prov. Antsiranana: Sommet du Marojejy, [14°25’48”S 49°43’48”E], 29.III.1947, Cours 3537 ( P [ P01640932 ], TAN); Vallée inférieure de l’Androranga , affluent de la Bemarivo (NE), aux env. d’Antongondriha , massif de Betsomanga , [14°15’30”S 49°44’00”E], 1300-1950 m, 17-20.XI.1950, Humbert & Capuron 24333 ( P [ P01640952 ]); Vallée de la Lokoho (NE) , Mt Beondroka au N de Maroambihy, [14°30’00”S 49°50’30”E], 1400-1450 m, 17-22.III.1949, Humbert & Capuron 23618 ( G, K, MO, P [ P00853045 ],); ibid. loc., Humbert & Capuron 23621 ( P [ P0073 0621]); Along the trail to the summit of Marojejy E , NW of Mandena , 14°26’S 49°43’E, 1900-2133 m, 15.II.1989, Miller & Lowry 4153 ( MO, P [ P00853038 ], TAN); Massif de Marojejy, [14°25’40”S 49°43’48”E], 2000-2137 m, XI.1972, Morat 4081 ( P [ P00853037 ]); ibid. loc., 10.5 km NW of Manantenina, along tributary at head of Andranomifototra river, 14°26’24”S 49°44’30”E, 1625 m, 4-13.XI. 1996, Rakotomalaza & al. 869 ( MO); ibid. loc., partie SW, 14°28’S- 14°37’S 49°33’E-49°42’E, 1295-1620 m, 12.V.1989, Randrianasolo 16 ( MO); ibid. loc., above Manentinina Village , 14°26’S 49°43’E, 1600-2137 m, 28.III.1990, Randrianasolo 139 ( MO, P [ P00730622 ], TAN); ibid. loc., 14°25’45”S 49°42’30”E, 1672 m, 9.III.1994, Rasoavimbahoaka & al. 161 ( MO, P [ P00730624 ], TAN); ibid. loc., au sommet de Marojejy, 14°26’50”S 49°43’57”E, 2132 m, 23- 24.III.1995, Rasoavimbahoaka & al. 520 ( MO, P [ P00730623 ], TAN).

Figures

Fig. 1. – Xyris marojejyensis Lock, Rakoton., Callm. & Phillipson. A. Whole plant growth habit; B. Infructescence; C. Inflorescence; D. Fruit with single lateral sepal showing toothed keel. [Humbert 22770, TAN] [Drawing: R. L. Andriamiarisoa]

Fig. 2. – Map showing the distribution of Xyris marojejyensis Lock, Rakoton., Callm. & Phillipson (stars) and Xyris labatii Rakoton., Callm. & Phillipson (circles) in Madagascar, plotted on the map of phytogeographical domains sensu HUMBERT (1955).