Rakotonirina, N., M. W. Callmander, P. B. Phillipson & J. M. Lock (2014). Two new species of Xyris L. (Xyridaceae) endemic to Madagascar with a key to the Malagasy species. Candollea 69: 171–178. In English, English and French abstracts.
A review of the available herbarium material and of the currently recorded species of the genus Xyris L. (Xyridaceae) from Madagascar in the context of the “Catalogue of the Vascular Plants of Madagascar” project has led us to identify two new species which are described here as: Xyris labatii Rakoton., Callm. & Phillipson and Xyris marojejyensis Lock, Rakoton., Callm. & Phillipson. This brings the total number of species that we recognize on the island to seven. A key to the Malagasy species of Xyris, illustrations of the new species and a discussion of their morphological affinities are provided, together with preliminary conservation status assessments following IUCN Red List Categories and Criteria.
Introduction
The family Xyridaceae is pantropical, and comprises c. 415 species (Campbell, 2014) in five genera, of which the genus Xyris L. is by far the largest, and contains all of the species occurring naturally in Africa and Madagascar (Lebrun & Stork, 2012). Species of Xyris consist of generally small herbs, usually less than 90 cm tall, with basal linear distichous leaves. The flowers are borne in dense cone-like inflorescences on elongated peduncles and have three delicate petals, usually yellow but sometimes white or blue (Lock, 2001). In his treatment for the “Flore de Madagascar et des Comores”, Perrier de la Bâthie (1946) recognized seven native species, all possessing yellow petals, and comprising the three endemic species: X. hildebrandtii L. A. Nilsson, X. madagascariensis Malme and X. humilis Kunth, and four others that were shared with continental Africa. Subsequent revisionary work for the continent by Lock (1998, 1999a, 1999b, 2010) has contributed to refining the taxonomy of Xyris, at least for those species shared with Madagascar. However it is clear that some species complexes are in need of further investigation throughout their distribution range, notably for those plants provisionally referred to X. anceps Lam. and X. capensis Thunb., which also occur in South America, and X. congensis Büttner (Lock, 1999b, 2001). Lock (1998: 889) stated sagely that: “The Madagascar species of Xyris are badly in need of revision”.
Lock's words cited above have been borne out by our taxonomic evaluation for the “Catalogue of Vascular Plants of Madagascar” (Madagascar Catalogue, 2014). Nevertheless we believe our investigations are a step towards an improved understanding of the diversity of Xyris in Madagascar. They have served to clarify the status of the known species and have highlighted the existence of two new species endemic to Madagascar that we describe in this article: X. marojejyensis Lock, Rakoton., Callm. & Phillip son and A. labatii Rakoton., Callm. & Phillipson. Our work is a step towards the full revision that is needed, but additional effort is certainly required to fully understand the three species complexes mentioned above.
Lock (1999a) also noted the possible occurrence of a fourth African species, X. angularis N. E. Br. in Madagascar, based on the Paris Herbarium sheet of Du Puy & al. M639 [P016760]. This material is mixed with X. congensis and no other material of X. angularis has been found among the Madagascar collections at the relevant herbaria. It is possible that the fragments of X. angularis are not part of Du Puy's gathering, and were mounted in error on the sheet, in which case it is possible that they may not even have originated from Madagascar. In the absence of further reports of this species in Madagascar we prefer to regard its presence in the country as doubtful.
We currently accept seven species of Xyris native to Madagascar, like Perrier de la Bâthie (1946), but we only retain two of them from the latter treatment, namely X. anceps and X. humilis. Most of the remaining material cited by Perrier de la Bâthie (1946) under his other five species: X. batokana N. E. Br., X. hildebrandtii, X. madagascariensis, X. semifuscata Baker and X. umbilonis L. A. Nilsson is best placed within either X. capensis or X. congensis as currently circumscribed. The notable exception is the type of X. baronii Malme (Scott-Elliot 2915) and (Humbert 5757), both from Taolognaro (Fort Dauphin) which Perrier de la Bâthie (1946) included in X. hildebrandtii. This species was subsequently subsumed under X. congensis (Lock, 1999b) together with its synonym X. baronii. While accepting the placement of X. hildebrandtii as a synonym of X. congensis, we believe that X. baronii should be resurrected, as a distinct species, for which a number of new collections are now available. This taxon occurs primarily in the South East of Madagascar at low elevations near Taolognaro, but there are also scattered collections from other localities near the east coast as far north as Nosy Boraha (Ile Sainte Marie). Xyris baronii differs from X. congensis by its longer leaves (c. 40–75 cm vs. 20–40 cm in X. congensis) ovoid- cylindrical (vs. ellipsoid) inflorescence and in its ovate (vs. elliptic) bracts.
In the present article we describe the two new Malagasy endemic species and provide a new identification key to the Malagasy species of Xyris. The new species are given preliminary risk assessments based on the IUCN Red List Categories and Criteria (IUCN, 2012). Calculations of the “Area of Occupancy” (AOO), “Extent of Occurrence” (EOO) and number of subpopulations were based on the methods presented in Callmander & al. (2007). A discussion of their morphological affinities is provided for each of the new species. Additional information for the other species from Madagascar and a complete synonymy for Xyris in Madagascar can be found in the Madagascar Catalogue (2014).
Key to the Malagasy species of Xyris
1 Keel of lateral sepals entire; bracts, leaf and stem bases pale or dark brown when dried 2
la. Keel of lateral sepals toothed, at least in the middle; bracts, leaf and stem bases always dark brown when dried 5
2 Scape spirally twisted, base swollen, bulbous; leaves filiform, c.l mm wide X. labatii
2a. Scape straight, not twisted, base not swollen; leaves linear, more than 2 mm wide 3
3. Bracts with a distinct sub-terminal, triangular or rhomboid mark; inflorescence broadly ovoid at anthesis, or rarely subspherical; plants perennial 4
3a. Bracts without a distinct sub-terminal, triangular or rhomboid mark; inflorescence sub-spherical at anthesis; plants usually annual X. capensis
4. Keel of lateral sepals not winged; bract apices conspicuously thickened, dark brown, somewhat recurved; plant less than 15 cm tall X humilis
4a. Keel of lateral sepals winged; bract apices not conspicuously thickened, light brown, not recurved; plant more than 25 cm tall X anceps
5. Leaves large (0.6–0.8 cm); inflorescence c. 10 mm in diam., broadly ovate-elliptic, not elongating with age X. marojejyensis
5a. Leaves narrow (< 0.3 cm); inflorescence < 6 mm in diam., sub-orbicular or ovate, becoming distinctly elongated with age 6
6. Leaves 40–75 × 0.3 cm; inflorescence ovoid-cylindrical, c. 2 cm long at anthesis X. baronii
6a. Leaves 20-40 × 0.15-0.2 cm; inflorescence ellipsoid, c. 1 cm long at anthesis X. congensis
Taxonomy
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 22 770 (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, lineare. 4×1 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 km2, and an AOO of 63 km2 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 [PO 1640952]); 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, 15.11.1989, 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).
Fig. 1. —
Xyris morojejyensis 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).
Xyris labatii Rakoton., Callm. & Phillipson, spec, nova (Fig. 3, 4).
Typus: Madagascar. Prov. Antananarivo: Ambatofinandrahana, massif de I'ltremo, Atsirakambiaty, 20°35′22″S 46°34′01″E, 1680 m, 27.III. 1999, fl., Labat 3050 (holo-: P [POO 160157]!; 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-)l–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 (l-)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 km2, and an AOO of 153 km2 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 [PO 1641000]); 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, 23.1.2000, Raynal-Roques & Jérémie 24816 (G, K, MO, P [P00853043], TAN, WAG); ibid, loc, 20°05′33″S 47°00′ 14″E, 2080 m, 16.11.2003, Schatz & al. 4075 (MO); ibid, loc., 20°04′10″S 47°00′16″E, 1700 m, 17.11.2003, 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, 27.1.1975, Croat 29532 (MO, P [P01640906], TAN); Vicinity of col de Itremo, [20°34′30″S 46°37′30″E], 1500–1685 m, 27.1.1975, Croat 29830 (MO, TAN); Env. d'Ambatofinandrahana, [20°33′S 46°48′E], 1600–1800 m, 19.11.1938, 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'ltremo, W of Ambatofinandrahana: Montagnes à l'W (W Betsileo), [20°34′30″S 46°37′30″E], 1500–1700 m, 17–22.1. & 18-22.IV.1955, Humbert 28325 (P [PO19524021]); ibid, loc., Humbert 29893 (P [PO1640936]); 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 [PO1640896]); 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 Ambatofmandrahana, along road to Col d'ltremo, 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'Ambatofmandrahana, 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, 9.11.2009, Rakotoarisoa 628 (K, MO, P, TAN).
Acknowledgments
The authors thank the Parc Botanique et Zoologique de Tsimbazaza and the Missouri Botanical Garden staff in Antananarivo for help and support in this study. We thank Roger Lala Andriamiarisoa for his fine illustrations and Lisa Campbell and Fred Stauffer for their very helpful review of an early version of this manuscript. We are also grateful to the curators of the following herbaria for access to their collections: G, K, MO, P, TAN and TEF. Financial support was by grants from the Andrew W. Mellon Foundation.
