Xyris labatii 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 : 175

Xyris labatii Rakoton., Callm. & Phillipson , spec. nova ( Fig. 3 , 4 ).

Typus: MADAGASCAR. Prov. Antananarivo: Ambatofinandrahana, massif de l’Itremo , Atsirakambiaty , 20°35’22”S 46°34’01”E, 1680 m, 27.III.1999, fl., Labat 3050 (holo-: P [ P00160157 ]!; iso-: G [ G00341191 ]!, K, MO!, TAN! ).

Haec species a congeneris madagascariensibus caule e base tumida orto, foliis filiformibus, caulibus scapisque spiraliter tortis atque seminibus obovoideis distinguitur.

Clumped perennial herb, tufted (10-) 20-50 cm. Stem spirally twisted, from the bulbous base to the shoot. Leaves up to 23 × 0.1 cm; sheaths (0.4-) 1-5 cm long, ridged, ligule c. 1 mm, slightly acute, brown-hyaline; blades filiform and coriaceous, strigillose, symmetric and aristate at the apex, margins thickened. Scapes up to (1-)8-28 × 0.1 cm, terete. Inflorescences ellipsoid, c. 0.3-0.6 × (3-) 0.5-0.6 cm, red-brown. Sterile bracts, 2-6, obovate, glossy brown, rounded to acute at the apex; fertile bracts ovate-elliptic c. 0.6 × 0.3 cm, apex acute, concave, smooth glossy brown, hyaline towards the margins, sometimes erose. Flower with lateral sepals c. 1.3 × 0.4 cm, slightly curved, keeled, hyaline and darker on the keel, smooth. Petals obovate, c. 0.1 × 0.08 cm yellow. Stamens 3, anther sessile, linear-shaped, c. 1.2 × 0.2 mm, epipetalous. Ovary obovate c. 3 × 1.2 mm, brown. Style 3-branched, 1.2 mm long; stigma twisted, 2.4 mm long. Fruits obovate, 2 × 1.5 mm, glabrous, with a longitudinal dark-brown dehiscence groove. Seeds obovoid, 0.3 × 0.2 mm, dark brown

Distribution and ecology. – Xyris labatii is known from the central highlands of Madagascar, in the Amoron’i Mania, Vakinankaratra and Haute Matsiatra regions. It grows on rocky areas, often on quartzite from 1200 to 2500 m ( Fig. 2 ).

Etymology. – The species epithet honours our friend and colleague, Jean-Noël Labat (1959-2011) who disappeared too soon. Jean-Noël collected the type specimen and as is often the case, he made a useful photograph to accompany his excellent collection.

Notes. – Xyris labatii can be recognized by its bulbous stem bases and its twisted leaves and scapes. It is similar to X. humilis , which also occurs in the central highlands of Madagascar, but the new species can be distinguished by its filiform leaves (vs. very narrowly linear in X. humilis ) (8-23 × 0.1 cm vs. 3-5 × 0.1-0.2 cm).

Conservation status. – With an EOO of 12,460 km ², and an AOO of 153 km ² and eleven subpopulations, two of which are in the protected area network (Andringitra), X labatii is assigned a preliminary status of “Least Concern” (LC) following IUCN Red List Categories and Criteria ( IUCN, 2012)

Paratypi. – MADAGASCAR. Prov. Antananarivo: Mont Ibity , c. 27 km SW of Antsirabe, 20°05’24”S 47°00’23”E, 1840-1890 m, 15.III.2004, Almeda 8706 ( CAS, TAN); Antsirabe, Beapombo, à 400 m avant d’arriver au sommet d’Ibity, 20°04’58”S 47°00’37”E, 2170 m, 5.II.2003, Andriamihajarivo 103 ( MO, P [ P00853040 ], TAN); ibid. loc., 20°10’S 47°03’E, 1300-1800 m, 6.III.1985, Dorr & al. 3853 ( MO, P [ P01641000 ]); ibid. loc., 20°07’00”S 47°01’00”E, 24.XII.1965, Peltier 2127 ( P [ P01640947 ]); Mahasoa à Ambohimasina, Betafo , [19°50’S 46°51’E], III.1976, A. Rakotozafy 1736 ( TAN); Hauts-plateaux, env. à 15 km à l’W de Arivonimamo (entre Arivonimamo et Soamahamanina, 60 km à l’W de Antananarivo), 18°54’43”S 47°05’21”E, 1260 m, 23.I.2000, Raynal-Roques & Jérémie 24816 ( G, K, MO, P [ P00853043 ], TAN, WAG); ibid. loc, 20°05’33”S 47°00’14”E, 2080 m, 16.II.2003, Schatz & al. 4075 ( MO); ibid. loc., 20°04’10”S 47°00’16”E, 1700 m, 17.II.2003, Schatz & al. 4130 ( MO, P, TAN). Prov. Fianarantsoa: Sommet très rocheux (quartzitique) à l’E d’Antsirakambiaty , à l’W d’Ambatoandrano, 20°34’39”S 46°34’26”E, 1681 m, 18.IV.2003, Andriamihajarivo 179 ( MO, P, TAN); 10 km W of Ivato on route #35, [20°34’30”S 46°37’30”E], 1500-1685 m, 27.I.1975, Croat 29532 ( MO, P [ P01640906 ], TAN); Vicinity of col de Itremo , [20°34’30”S 46°37’30”E], 1500-1685 m, 27.I.1975, Croat 29830 ( MO, TAN); Env. d’Ambatofinandrahana , [20°33’S 46°48’E], 1600-1800 m, 19.II.1938, Decary 12993 ( P [ P00853042 ]) ; ibid. loc., Decary 13090 ( P [ P00853041 ]) ; Mt Boby , [22°11’S 46°53’E], 20. III.1945, Homolle 1209 ( P [ P01924015 ]) ; ibid. loc., Homolle 1201 ( P [ P01924014 ], TAN) ; Massif de l’Andringitra ( Iratsy ), vallées de la Riambava et de l’Antsifotra et montagnes environnante, [22°12’S 46°55’E], 2000- 2500 m, 27. XI.1924, Humbert 3890 ( P [ P01640921 , P01640957 ]) ; Massif de l’Itremo , W of Ambatofinandrahana: Montagnes à l’W ( W Betsileo), [20°34’30”S 46°37’30”E], 1500-1700 m, 17-22. I. & 18- 22.IV.1955, Humbert 28325 ( P [ P019524021 ]) ; ibid. loc., Humbert 29893 ( P [ P01640936 ]) ; ibid. loc., Humbert 29936 ( G, K, MO, P [ P00730639 , P00730641 ], TAN, WAG) ; Route Ambositra à Ambatofinandrahana sur rocher après l’embranchement d’Ivato, 20°33’S 46°48’E, III.1960, Keraudren 158 ( P [ P01640896 ]) ; Itremo mountain , c. 1 km below the highest point of the road, 20°36’S 46°35’E, 1600 m, fl., 17. III.1995, Lye, Arnstein & Ranaivojaona 20894 ( TAN) ; Itremo massif, W of Ambatofinandrahana, along road to Col d’Itremo, ca. 2 km before ( NE of) bridge over Ambalarangolana creek, 20°33’58”S 46°35’35”E, 1450 m, 10.XI.2002, Lowry & al. 5914 ( MO, TAN) ; ibid. loc., 20°40’S 46°35’E, 1600 m, fl., 23. III.1971, Mabberley 780 ( K, TAN) ; ibid. loc., [20°37’S 47°12’E], 24.XII.1965, Peltier 5612 ( P [ P0164927 ]) ; ibid. loc., 20°36’45”S 46°35’05”E, 1650 m, 14. III.1992, Phillipson, Clement & Rafamantananantsoa 3889 ( MO, TAN) ; ibid. loc., inselberg à 11,7 km d’Ivato vers la route d’Ambatofinandrahana, et c. 4 km avant le village d’Anjoman’ Ankona, 20°39’45”S 47°07’42”E, 1500 m, fl., 24. III.2010, Rakotoarivelo & al. 330 ( MO, P, TAN) ; ibid. loc., about 6 km NW of Itremo , 20°33’35”S 46°34’55”E, 1333 m, 9.II.2009, Rakotoarisoa 628 ( K, MO, P, TAN) .

Figures

Fig. 3. – Xyris labatii Rakoton., Callm. & Phillipson. A. Whole plant showing swollen bulbous base; B. Infructescence; C. Fruit; D. Fruit with sepal pair showing toothed keels; E. Seed; F. Inflorescence. [A-B, D-F: Labat 3050, TAN; C: ScHatz & al. 4130, TAN] [Drawing: R. L. Andriamiarisoa]

Fig. 4. – Type of Xyris labatii Rakoton., Callm. & Phillipson. Type collection (Labat 3050) in its natural habitat on Itremo. [Photo: J.-N. Labat]

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).