Phytotaxa 159 (3): 221–235 www.mapress.com / phytotaxa / Copyright © 2014 Magnolia Press ISSN 1179-3155 (print edition) Article PHYTOTAXA ISSN 1179-3163 (online edition) http://dx.doi.org/10.11646/phytotaxa.159.3.5 Taxonomic revision of the Malagasy endemic and enigmatic Euphorbia section Pachysanthae (Euphorbiaceae) XAVIER AUBRIOT1, 2, PORTER P. LOWRY II1, 3 & THOMAS HAEVERMANS1 ISYEB, Institut de Systématique, Évolution, Biodiversité (UMR 7205 CNRS, MNHN, EPHE, UPMC), Muséum national d’histoire naturelle, National Herbarium, CP 39, 57 rue Cuvier, 75231 Paris CEDEX 05, France. E-mail: aubriot@mnhn.fr; lowry@mnhn.fr; haever@mnhn.fr 2 Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, England, UK. E-mail: x.aubriot@nhm.ac.uk (corresponding author) 3 Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166-0299, USA. E-mail: pete.lowry@mobot.org 1 Abstract Among the more than 170 species of Euphorbia (Euphorbiaceae, Malpighiales) that occur in Madagascar, some remain poorly known and dramatically under-collected, and are based on vague and incomplete descriptions. As part of an ongoing study of the genus in Madagascar, a revision is presented of E. section Pachysanthae, which comprises six species endemic to this island that show clear morphological affinities to one another. Expanded descriptions are provided for the four species already named, and the two others are described as new (Euphorbia haevermansii and Euphorbia nusbaumeri), both from the Daraina region in north-eastern Madagascar. An identification key is provided to the species, which are characterized by having developed leaves, unarmed twigs (unlike most of Malagasy Euphorbia), leafy deciduous cyathophylls, and ecarunculate seeds. Members of the section differ from one another in their geographical distribution, habit, and the shape and the size of their leaves, glands, cyathia and cyathophylls, as well as the size, surface and number of locules of the fruits. The morphological affinities of these six species are discussed and preliminary conservation assessments are provided. Introduction The genus Euphorbia Linnaeus (1753: 450) (Euphorbiaceae, Malpighiales) is a giant among flowering plants: it has a worldwide distribution and comprises about 2000 species and infraspecific taxa (Haevermans 2003, Mabberley 2008). The island of Madagascar, with at least 170 taxa of Euphorbia, almost all endemic (Haevermans 2003), stands out as one of the main hotspots of the genus. Despite this remarkable diversity, the most recent global revision of the genus dates from the 19th century (Boissier 1862). Results from recent molecular phylogenetic analyses, based on both nuclear and plastid markers, have revealed many monophyletic groups and shown that traditional infrageneric systems of classification in large part fail to reflect evolutionary relationships (Steinmann & Porter 2002, Haevermans 2003, Bruyns et al. 2006, Zimmermann et al. 2010, Dorsey et al. 2013). These phylogenetic studies, however, provide a framework for an ongoing series of taxonomic revisions of well supported, monophyletic groups. The present paper focuses on a distinctive clade endemic to Madagascar, E. section Pachysanthae X.Aubriot & Haev. in Dorsey et al. (2013: 309). Although poorly sampled in the abovementioned phylogenetic studies, this clade nevertheless forms a coherent group, both morphologically and geographically. It comprises four described species of trees [viz. E. elastica Jumelle (1905a: 1047), E. mananarensis Leandri (1945: 69), E. mandravioky Leandri (1957: 499) and E. pachysantha Baillon (1886: 624)] that share several features, including more or less pachycaul trunks, developed leaves, unarmed twigs, leafy deciduous cyathophylls and ecarunculate seeds. When Baillon described Euphorbia pachysantha in 1886, he placed it in the highly heterogeneous group E. section Goniostema Baill. ex Boissier (1862: 10). This section, lectotypified a posteriori with E. lophogona Accepted by Hans-Joachim Esser: 15 Dec. 2013; published: 14 Feb. 2014 221 Lamarck (1788: 417) (see Wheeler 1943), initially included all Malagasy species with well developed leaves and thus resulted in a “catch-all” group. Boissier (1862 and supplement in 1866) and Baillon (1886) expanded the section with the addition of numerous unarmed species. Bentham & Hooker (1880) later reduced this group to subsectional rank, placing it within section Euphorbium Bentham & Hooker (1880: 260), and subsequently Denis (1921) added the newly discovered E. elastica. In the same paper, Denis also proposed that four taxa with stipules forming laciniate ridges be transferred to E. subsect. Diacanthium (Boissier 1862: 10) Bentham & Hooker (1880: 260), which included all spiny Euphorbia from throughout the world. In 1945, Leandri, following Denis, excluded the species with stipules forming laciniate ridges and, without proposing a new name for the former subsect. Goniostema (Baill. ex Boiss.) Bentham & Hooker (1880: 260), included in it the newly discovered E. mananarensis. Subsequently, Leandri formally published a new name for the group: E. subsect. Denisophorbia Leandri (1957: 500), designating E. pyrifolia Lamarck (1788: 419) as the type. At the same time he described a new species, E. mandravioky, which he also placed in the subsection. In a recent phylogenetic study based on molecular sequence data, Bruyns et al. (2006) proposed a new infrageneric classification for Euphorbia in southern Africa in which they expanded E. sect. Goniostema to include all of the species formally placed in subsects. Goniostema, Diacanthium, Denisophorbia and Deuterocalli Croizat (1972: 179). Several other studies have, however, shown that adopting such a broad circumscription results in a polyphyletic group (Horn et al. 2012, Aubriot 2012, Dorsey et al. 2013). In particular, E. pachysantha and its relatives, none of which was included in the sampling used by Bruyns et al. (2006), do not show a close affinity to the taxa assigned to the expanded sect. Goniostema, which are themselves intimately related to the spiny AfroAsian species (sect. Euphorbia sensu Dorsey et al. 2013) and to the taxa heretofore placed in the genus Monadenium Pax (1894: 126) [sect. Monadenium (Pax) Bruyns (2006: 411) sensu Dorsey et al. 2013]. Notwithstanding these taxonomic inconsistencies based on sampling issues, all recent molecular phylogenetic studies that included more than one member of Euphorbia sect. Pachysanthae indicate that they form a distinct clade, separate from all other Malagasy taxa (Aubriot 2012, unpubl. data). Based on these studies and on the fact that E. sect. Pachysanthae forms a morphologically sound and coherent group, we present here a comprehensive taxonomic revision in which a total of six species are recognized, two of which are described as new. Each of the four previously described taxa was originally based on a very limited number of often fragmentary specimens, without illustrations or photos, and their protologues thus lacked clarity and accuracy. By using additional material collected during fieldwork in Madagascar conducted over the last decade, we have been able to standardize and amend the descriptions for these four species, two of which, E. pachysantha and E. elastica, are also lectotypified. The two new species, both collected within the last few years in the Loky-Manambato (Daraina) region of northeastern Madagascar, are described and illustrated. All six members of E. sect. Pachysanthae are assigned a preliminary conservation status. Material and Methods Morphological measurements were made on exsiccatae and alcohol-preserved material available in the herbaria in Geneva (G), Kew (K), University of Michigan (MICH), Saint Louis (MO), Paris (P), and Antananarivo (TAN). When historical collections lacked geographic coordinates, post-facto georeferencing (indicated in square brackets) was done using the “Gazetteer to Malagasy Botanical Collecting Localities” (Schatz & Lescot 2005) and other sources. Preliminary risk of extinction assessments were based on the calculations of the area of occupancy (AOO) and extent of occurrence (EOO), which were performed using the methods of Callmander et al. (2007). Conservation statuses were assigned using the IUCN Red List Categories and Criteria (IUCN 2012). Digital images of all type specimens in the Paris herbarium are available via the Sonnerat/BryoMyco database (Sonnerat/BryoMyco 2013) and some images of the material in the Geneva herbarium can be accessed through the Catalogue des Herbiers de Genève (CHG 2013). 222 • Phytotaxa 159 (3) © 2014 Magnolia Press AUBRIOT ET AL. Results Characterization and circumscription of Euphorbia sect. Pachysanthae Euphorbia sect. Pachysanthae X.Aubriot & Haev. in Dorsey et al. (2013: 309). Type: Euphorbia pachysantha Baill. Small to medium-sized trees, 3–20 m tall; bark gray, smooth to wrinkled; trunk “bottle-shaped” and unbranched at the base [resembling Adansonia spp. (Malvaceae)], stems succulent, grouped at the top; leaves spirally arranged toward the ends of the twigs, blade obovate to lanceolate, more or less shiny and succulent, apex acuminate to mucronate, sometimes retuse, petioles more or less developed with two small stipular glands at the base. Sexual system difficult to determine given the fragmentary record of flowering stages, but apparently monoecious in most species with the cyathia bisexual and functionally protandrous. Inflorescences sub-terminal, cyathia solitary or grouped by 2 to 4 at the ends of the twigs, cyathophylls usually 2, developed, leafy, deciduous, glands and interglandular bracts 5. Capsules erect or pendant, very variable in size, sometimes trilocular but more often 2- or 1-locular by abortion, green when young, smooth to weakly wrinkled; 1- to 3-seeded, testa smooth, lacking a caruncle. Key to the species of Euphorbia sect. Pachysanthae 1. 2. 3. 4. 5. - Small tree to 6 m tall, leaves small (2–3 × 1–1.5 cm), obovate, succulent; cyathia usually small (6–7 mm in diameter). Xeric bushland, south-eastern Madagascar (near Fort-Dauphin)...................................................................E. mananarensis Small tree to tree (3–30 m tall), leaves large (generally >5 cm long), shape variable, from obovate to elliptic, more or less succulent; cyathia large (>8 mm in diameter). Deciduous or humid forest, northern, western and eastern Madagascar … 2. Cyathium glands crescent-shaped, bearing appendices recurved towards the cyathium cup, glands attached to the cyathium cup by a short stalk (2 mm long), cyathium divided into 5 units separated by bracteoles, peduncle of cyathium 2–4 mm long; trees 3–6 m tall, humid forests, eastern Madagascar .............................................................................E. pachysantha Cyathium glands circular to reniform, never crescent-shaped, directly inserted on the cyathium cup, peduncle of cyathium 6–15 mm long; trees 3–30 m tall. Deciduous and semi-deciduous forests of northern and western Madagascar................ 3. Leaves succulent; fruit unilocular or bilocular, large (2.5–4 cm in diameter), pendulous when ripe ............. E. mandravioky Leaves not succulent or only slightly so; fruit unilocular to trilocular, never exceeding 2 cm in diameter when mature, erect when ripe .............................................................................................................................................................................. 4. Fruits trilocular, spherical, surface smooth; bark thick, strongly desquamating (as in some species of Prunus L.); trees to 20(–30) m tall. Relictual forests, Ambongo plateau SE of Mahajanga (western Madagascar) ..............................E. elastica Fruits unilocular or trilocular, trigonous or spherical, surface smooth or sulcate; bark smooth; trees 6–11 m tall. Semideciduous forests, north eastern Madagascar ....................................................................................................................... 5. Fruits trilocular, trigonous, surface sulcate, solitary or borne in pairs, ca. 2 cm in diameter when mature; leaves large (generally >7 cm long) ......................................................................................................................................... E. haevermansii Fruits unilocular, spherical, surface smooth, usually 2 to 4 borne together, ca. 1 cm in diameter when mature; leaves small (generally <6 cm long) .................................................................................................................................... E. nusbaumeri Euphorbia elastica Jumelle (1905a: 1047) (Figure 1). [non Euphorbia elastica Poisson & Pax (1902: 60), nom. prov. inval., non Euphorbia elastica Altamirano & Rose (1905: 323), nom. illeg., non Euphorbia elastica Marloth (1912: 37), nom. illeg.]—Euphorbia pirahazo Jumelle (1905b: 207), nom. illeg. superfl. Lectotype (designated here):—MADAGASCAR. Mahajanga Province: Environs d'Antsirabe près Andranomavo (Ambongo), [16°50’S, 45°39’E], November 1904, fl., Perrier de la Bâthie 1664 (lectotype P [P00169658]!; isolectotypes K [K000185254]!, P [P00169657]!, [P00751346]!). Trees 10–20(–30) m tall, monoecious, deciduous, pachycaulous, trunk straight, rounded at the unbranched base, to 30(–60) cm in diameter, weakly branched at the top; bark whitish-gray, exfoliating longitudinally by rolling into cylinders as in some Prunus spp., with large corky lenticels 0.8–2 cm in diameter; secondary branches slender, small. White latex present in all organs, having the consistence of rubber at the base of the trunk. Leaves simple, alternate, grouped at the ends of the twigs, blade light green abaxially, dark green adaxially, thin, obovate to spatulate, (7–)8–10(–11) × 4–5 cm, glabrous, primary and secondary veins light green to white, well impressed adaxially, base attenuate, margin entire, apex wide, strongly acuminate to mucronate; petioles 1(–1.5) cm long, light green to white, glabrous; stipules 2, gland-like. Cyathia pseudoterminal, solitary or 2 or 3 grouped at the top MALAGASY EUPHORBIA SECTION PACHYSANTHAE Phytotaxa 159 (3) © 2014 Magnolia Press • 223 FIGURE 1. Euphorbia elastica. A, B. Leaves. C. Bark. D. Detail of a terminal cyathium. E. Cyathophyll. F. Female flower. G. Detail of a fertile branch showing a terminal young fruit. H. Fruit. A–B, D–E after Perrier de la Bâthie 1664 (P), C, H after Bollinger et al. RFB 255 (G), F after Gautier et al. LG 5701 (G), G after Perrier de la Bâthie 9756 (P). 224 • Phytotaxa 159 (3) © 2014 Magnolia Press AUBRIOT ET AL. of the twigs, functionally protandrous, cupuliform, 1–1.8 cm in diameter when dry (including the glands), glabrous. Cyathia borne on peduncle 0.6–1.5 cm long; cyathophylls 2, deciduous, glabrous, spatulate to obovate, 1.5–2 × 0.9–1.1 cm, apex mucronate, inserted at the base of the peduncle (male phase cyathia) or ¾ of the distance from the base of the peduncle (female phase cyathia), subopposite. Glands 5, fleshy, contiguous to slightly overlapping one another, almost twice as long as wide (5–6 × 2.5–4 mm), elliptic, strongly bilabiate, glabrous, gland margins minutely fimbriate. Interglandular bracts straight, orbicular (3 × 3 mm), greenish-yellow, with deeply laciniate margins. Staminate flowers numerous, borne on pedicels 3–8 mm long, filaments very small to absent, anthers 1 mm in diameter; bracteoles hyaline, numerous, filamentous, lingulate. Pistillate flower erect, inserted in the center of the cyathium, tricarpellate, glabrous, styles 4 mm long, connate from the base to the middle, curved at the top, stigmas 3, bifid, brown. Young fruit solitary, erect, peduncle green, ribbed, 1–2.7 cm long; fruit green when fresh, bilocular by abortion, globular, 1–1.5 cm in diameter, stigmas persistent, recurved at the top, exocarp smooth, glabrous, covered by more or less prominent wrinkles. All known fruits aborted, seeds thus unknown. Distribution and ecology:—Long considered possibly extinct, this species has been collected only four times, twice by Perrier de la Bâthie in 1904 (the type collection) and 1910 in relict High Plateau forest near Adranomavo (between 50 and 600 m elevation), in the vicinity of Antsirabe (southeast of Mahajanga), in central-western Madagascar, and then in 2011 and 2012 during expeditions to the dry forest of Beanka (in the vicinity of Bemaraha reserve), in central-western Madagascar, where it was collected on tsingy between 284 and 355 m elevation. Additional specimens examined:—MADAGASCAR. Province de Majunga/Mahajanga: Beanka, partie sud, Sarodrano, 18°03’06”S, 44°32’06”E, 355 m, 25 February 2012, fr., Bollinger et al. RFB 255 (G); Province de Majunga/Mahajanga, Beanka, partie sud, Sarodrano, 18°03’45”S, 44°31’30”E, 284 m, 22 November 2011, fl., Gautier et al. LG 5701 (G); Ankissompo[b?]e près d’Ambatonhikina (Bemarivo) [unreadable and unobtainable locality], December 1910, fr., Perrier de la Bâthie 9756 (P). Conservation status:—With an Area of Occupancy (AOO) of 18 km2, just four known collections (one of them without interpretable locality data) and two subpopulations (one of which occurs within the tsingy forest of Beanka, an area targeted for protection by Biodiversity Conservation Madagascar), we have assigned Euphorbia elastica a preliminary status of “Critically Endangered” [CR C2a(i)+D] based on the IUCN Red List Categories and Criteria (IUCN 2012). Euphorbia haevermansii X.Aubriot & Lowry, sp. nov. (Figure 2). E. elasticae et E. pachysanthae affinis est, sed prima cortice laevi, atque secunda capsula 3-seminali, trigona, profunde sulcata, glandibus ellipticis in cyathio sessilibus differt. Type:—MADAGASCAR. Province de Diego-Suarez/Antsiranana: Sous-préfecture de Vohemar, commune rurale de Daraina, forêt d’Ankaramy, 13°18’S, 49°40’E, 640 m, 19 December 2005, fl., Ranirison & Nusbaumer PR 1035 (holotype P [P00751343]!; isotypes G [G00090464]!, TEF). Small to medium-sized trees to 11 m tall, sexual system unclear; trunk to 14 cm in diameter, unbranched at the base; bark smooth, lenticelate; secondary branches slender and numerous, forming a crown at the ends of the twigs, young branches rounded, green. White latex present in all organs. Leaves simple, alternate, grouped at the ends of the twigs, blade shiny, light green abaxially, dark green adaxially, fleshy, obovate to spatulate, about twice as long as wide, (5–)7–8(–11) × 3–4(–5) cm, glabrous, primary vein light green, well impressed adaxially, secondary veins numerous, inconspicuous, base attenuate, margin entire, smoothly revolute, apex finely acuminate to mucronate; petiole (1–)1.5–1.7(–2) cm long, light green, glabrous; stipules 2, gland-like. Cyathia pseudo-terminal, solitary, less often in pairs, obconical and broadly spreading, 1 cm in diameter when dry (including the glands), glabrous. Cyathia at male phase borne on peduncles 4 mm long; cyathophylls 2, deciduous, glabrous, spatulate, 1 × 0.5–0.7 cm, apex mucronate, inserted at the base of the peduncle, borne on petioles 5 mm long. Glands 5, fleshy, thick, contiguous, 5 × 3 mm, elliptic to reniform, slightly bilabiate, outstreched, glabrous; surface light green, weakly dotted; margin yellow green, thickened, slightly revolute. Interglandular bracts upright, orbicular (3 × 3 mm), glabrous, green, margin laciniate. Staminate flowers numerous, organized in 5 cymes, surrounded by a network of numerous bracteoles, filamentous, lingulate, hyaline. Staminate flowers well exserted from the cyathium cup at maturity, each borne on a pedicel 6 mm long, filaments thin, 3 mm long, anthers light-green, 0.5 mm in diameter. Cyathia at female phase solitary or in pairs, peduncles 1.2 cm long; cyathophylls 2, deciduous, inserted at the base of the cup. Female flower unknown. Mature fruit 1(or 2) borne at the ends of the fertile twigs, erect, peduncle MALAGASY EUPHORBIA SECTION PACHYSANTHAE Phytotaxa 159 (3) © 2014 Magnolia Press • 225 green, ribbed, 1.2 cm long, green when fresh, trilocular, 3-angled, sulcate, glabrous, 2 cm in diameter, stigmas 3, persistent, straight, borne at the apex of the fruit. Seeds 3, 3-angled, 1.2 × 1.2 cm, 2-lobed with a persistent hilum at maturity, testa smooth, brown, glabrous. FIGURE 2. Euphorbia haevermansii. A. Habit. B. Leaf. C. Cyathium with cyathophylls. D. Cyathophyll. E. Detail of a fertile branch showing two terminal mature fruits. F. Fruits, the one on the left cut open to show the three locules and three seeds inside. G. Ventral, lateral and dorsal views of a seed. A–D after Ranirison & Nusbaumer PR 1035 (G, P), E–G after Nusbaumer LN 865 (G). 226 • Phytotaxa 159 (3) © 2014 Magnolia Press AUBRIOT ET AL. Etymology:—This new species is named in honor of our friend and colleague Thomas Haevermans as a mark of recognition for his invaluable contribution to improving our understanding of Malagasy Euphorbia. Thomas’ studies have opened the way for developing an improved classification of the group, and his research has been important in strengthening our understanding of the processes responsible for plants diversification in Madagascar. Distribution and ecology:—Deciduous and semi-deciduous forests in the Daraina region of northeastern Madagascar, at 600–700 m elevation. Additional specimens examined (paratypes):—MADAGASCAR. Province de Diego-Suarez/Antsiranana: Sous-préfecture de Vohemar, commune rurale de Daraina, forêt de Binara, 13°15’S, 49°37’E, 715 m, 21 December 2003, fr., Nusbaumer LN 865 (G, K, P); Sous-préfecture de Vohemar, commune rurale de Daraina, forêt d’Ankaramy, 13°18’S, 49°40’E, 23 February 2004, fr., Ranirison & Nusbaumer PR 464 (G); Antsiranana: Ambilobe, Betsiaka, forêt d'Andavakoera, 8 km au nord de Betsiaka, Dilan'Antemoro, 13°7’47”S, 49°13’42”E, 508 m, 11 January 2006, fl., Razafitsalama et al. 900 (CNARP, MO, P, TAN). Conservation status:—Euphorbia haevermansii has an Extent of Occurrence (EOO) of ca. 20 km2, an Area of Occupancy (AOO) of 27 km 2, and is known from two subpopulations (one of which occurs within the Loky Manambato protected area). Consequently, we assign E. haevermansii a preliminary status of “Endangered” [EN B1ab(i,ii,iii)+2ab(i,ii,iii)] based on the IUCN Red List Categories and Criteria (IUCN 2012). Notes:—Euphorbia haevermansii closely resembles to E. pachysantha and E. elastica. It differs from E. elastica, however, by several morphological characters: it is a small tree (up to ca. 10 m tall) with a smooth bark and trilocular fruits, whereas E. elastica is a large tree (20 m tall) with the bark rolled into cylinders (as in some species of Prunus) and has bilocular fruits (by abortion). Euphorbia haevermansii differs from E. pachysantha in having cyathium glands that are elliptic to reniform and directly inserted on the cyathium cup, rather than crescent shaped and borne on a stalk. Euphorbia haevermansii is known only from forests in the area near the LokyManambato reserve in northern Madagascar, whereas E. elastica grows in remnant dry, deciduous forest in western Madagascar and E. pachysantha occurs in rainforest in eastern Madagascar. Euphorbia mananarensis Leandri (1945: 69) (Figure 3). Type:—MADAGASCAR. Toliara Province: Vallée de la haute Mananara (limite orientale de l’Androy), pente gneissique, [24°49’S, 46°37’E], 25 November 1931, fl., Decary 9413 (holotype P [P00078031]!; isotypes K [K000185028]!, P [P00078032]!, TAN [TAN000553]!). Small trees to 6 m tall, monoecious, pachycaulous, trunk rounded at the base, to 40 cm in diameter, unbranched at the base; bark brown, slightly wrinkled; branches slender, small, pseudodichotomous, with blackish bark. Abundant white latex present in all organs. Leaves simple, alternate, grouped at the ends of the twigs, blade shiny, light green abaxially, dark green adaxially, thick, fleshy, elliptic to obovate, (0.9–)2–3(–4.3) × (0.8–)1–1.5(–2.3) cm, glabrous, primary and secondary veins forming light green dots, inconspicuous, secondary veins ca. 3 to 6 per side, base attenuate, margin entire, minutely revolute, apex wide and usually almost flat, acumen more or less developed (rarely absent); petiole very short (1–5 mm long) to absent (leaves sessile), light-green to white, glabrous; stipules 2, minute, gland-like. Cyathia pseudoterminal, solitary, functionally protandrous, cupuliform to obconical, (0.4–)0.6–0.7(–0.8) cm in diameter when dry (including the glands), glabrous. Cyathia at male phase borne on peduncles 2–4 mm long; cyathophylls not developed. Glands 5, fleshy, contiguous, almost as long as wide (4 × 3 mm), reniform to ovate, glabrous, gland margins smooth, revolute. Interglandular bracts 5, as long as wide (2 × 2 mm), orbicular, glabrous, with filamentous margins; staminate flowers numerous, divided into 5 clearly distinguishable cymes, pedicels 2 mm long, filaments thick, very small, 0.5 mm long, anthers 1 mm in diameter; staminate flowers weakly exserted from the cyathium cup at maturity, hyaline bracteoles numerous, united to the base of the staminate flowers, filamentous, lingulate. Cyathia at female phase with peduncle (4.5–)6–7(–8.5) mm long; cyathophylls 2, deciduous, glabrous, lingulate, 5 × 3 mm, inserted ¾ of the distance from the base of the peduncle, subopposite; pistillate flower erect, in the center of the cyathium, bicarpellate, glabrous, style very short, stigmas 2, bifid, brown. Mature fruit solitary, erect, peduncle green, smooth, 0.7–1 cm long; fruit green when fresh, usually unilocular (sometimes bilocular), comprising a large globular lobe 1.3–1.6 cm in diameter when dry plus an aborted lobe, conical to hemispherical, <7 mm high; exocarp hard, smooth, glabrous, covered by more or less prominent wrinkles, a sclerotic crest visible in longitudinal section. Seed 1(or 2), globular, smooth, brown, glabrous, 1.4 cm in diameter. MALAGASY EUPHORBIA SECTION PACHYSANTHAE Phytotaxa 159 (3) © 2014 Magnolia Press • 227 Distribution and ecology:—Euphorbia mananarensis grows in xeric bushland in southeastern Madagascar, near Fort-Dauphin (Tolagnaro), at 100–900 m elevation. FIGURE 3. Euphorbia mananarensis. A. Habit. B. Bark. C. Leaves. D. Detail of a cyathium. E. Cyathophylls. F. Young female flower. G. Front and side views of two fruits. H. Front view of a seed. I. Cross section of the fruit and the seed. A–C, G–I after Aubriot et al. 55 (P), D–F after Service Forestier (Capuron) 18692 (P). 228 • Phytotaxa 159 (3) © 2014 Magnolia Press AUBRIOT ET AL. Additional specimens examined:—MADAGASCAR. Toliara Province. Flanc de colline, dans la forêt sèche, à 32 km au nord-est d'Amboasary, 24°53’15”S, 46°39’24”E, 457 m, 29 November 2009, fr., Aubriot et al. 55 (G, K, MICH, MO, P, TAN); Sud-ouest: Crête et flanc Sud-Est du massif du Vohimena, au S.W. d'Antamimora, [24°52’S, 45°32’E], 7 July 1958, fl., Service Forestier (Capuron) 18692 (P); Toliara: Préfecture de Fort-Dauphin; forêt sèche de Vinanibe; bush, [25°3’20”S, 46°52’12”E], 100 m, 17 October 1990, fl., Dumetz 1303 (P, TAN); Vallée de la Manambolo, rive droite (Bassin du Mandrare) aux environs d'Isomonony (confluent de la Sakamalio), [24°31’S, 46°37’E], 400–900 m, December 1933, fr., Humbert 13072 (P); Fort-Dauphin, Ambatoabo, Savoa, 2.5 km est d’Imonty, 24°47’48”S, 46°42’16”E, 200 m, 27 November 2009, fr., Ratovoson 1548 (P, TAN). Conservation status:—Euphorbia mananarensis has an Extent of Occurrence (EOO) of ca. 3770 km2, an Area of Occupancy (AOO) of 54 km2, and is known from four separate subpopulations (only one of which occurs within a protected area, i.e. Andohahela National Park). Consequently, we have assigned a preliminary status of “Endangered” [EN B1ab(i,ii,iii)+2ab(i,ii,iii)] based on the IUCN Red List Categories and Criteria (IUCN 2012). Euphorbia mandravioky Leandri (1957: 499) (Figure 4). Euphorbia capuronii Leandri (1956: 608), nom. illeg., non Euphorbia capuronii Ursch & Leandri (1954: 170). Type:— MADAGASCAR. Antsiranana Province: Ouest (Nord) Plateau de l’Ankarana: sur les calcaires, aux environs d’Ambondromifehy, [15°53’S, 49°13’E], 4 October 1954, fl., Service Forestier (Capuron) 11254 (holotype P [P00078036]!; isotypes P [P00078037]!, [P00078038]!). Trees 12–20 m tall, monoecious, deciduous, pachycaulous, trunk straight, rounded at the base, similar to that of Adansonia spp., to 1 m in diameter at the unbranched base, weakly branched at the top; bark gray, smooth, with large corky lenticels >2 cm in diameter, these sometimes contiguous, forming transversal wrinkles round the trunk. White latex present in all organs. Leaves simple, alternate, usually arranged spirally at the ends of the twigs, blade light green abaxially, shiny green adaxially, thick, fleshy, obovate to obcordate, about twice as long as wide, (3.6–)5.8– 7.5(–9.6) × (1.9–)3.2–4.1(–5) cm, glabrous, primary vein weakly impressed adaxially, secondary veins inconspicuous, ca. 7 per side, base attenuate, margin entire, smoothly revolute, apex wide, strongly acuminate or retuse; petioles 1(–1.5) cm long, light-green to white, glabrous; stipules 2, gland-like (0.5 mm in diameter). Cyathia pseudoterminal, solitary or paired, functionally protandrous, cupuliform to obconical with a broadly spreading base, 0.7–0.8(–1) cm in diameter when dry (including the glands), glabrous, peduncles (1–)1.3–1.5 cm long; cyathophylls 2, deciduous, glabrous, spatulate, 6 × 3 mm, inserted ¾ of the distance from the base of the peduncles, subopposite. Glands 5, fleshy, thick, contiguous, in general two times longer than wide, 3–6 × 1.5–3 mm, distinctly reniform, strongly bilabiate, glabrous, gland margins undulate, slightly revolute, with inconspicuous appendices recurved towards the cyathium cup. Interglandular bracts straight, almost as long as wide (3 × 2 mm), orbicular to spatulate, margins fimbriate. Staminate flowers numerous, divided into 5 clearly distinguishable cymes, separated by a net of small hyaline bracteoles. Staminate flowers weakly exserted from the cyathium cup at maturity, pedicel 4 mm long, filaments thick, small, 1 mm long, anther 1 mm in diameter. Pistillate flower erect, inserted in the centre of the cyathium, bicarpellate, glabrous, style very short, stigmas 2, bifid, brown. Mature fruit solitary, pendulous, peduncle gray, woody, 1.7–2 cm long; green when fresh, unilocular or bilocular, globular, 2.5–4 cm in diameter when dry, coriaceous, exocarp slightly wrinkled, glabrous, with prominent longitudinal ridges. Seed 1, ovoid, smooth, brown, glabrous, 3 × 2.5 cm. Distribution and ecology:—Deciduous and semi-deciduous forests of northern Madagascar (calcareous plateau of the Ankarana reserve, Montagne des Français near Diego Suarez, and the Daraina region), at 50–600 m elevation. Additional specimens examined:—MADAGASCAR. Antsiranana Province, forêt de Bekaraoka, près du Camp Tattersalli, à 6 km au nord-est de Daraina, 13°10’00”S, 49°42’26”E, 185 m, 14 May 2010, st., Aubriot et al. 107 (MO, P, TAN) and Aubriot et al. 108 (P, TAN); Montagne des Français, à 8 km au sud-est de Antsiranana (Diego-Suarez), 12°22’33”S, 49°20’27”E, 376 m, 20 May 2010, st., Aubriot et al. 134 (G, P, TAN); Antsiranana, sous préfecture de Vohemar, commune rurale de Daraina, fokontany d'Ankijabe, forêt de Binara, camp I, 13°15’S, 49°37’E, 500 m, 6 November 2001, fr., Gautier & Ravelonarivo 4078 (K, P); Antsiranana, Vohemar, Ampisikinana, Tsaratanana, forêt Ampondrabe, 12°58’12”S, 49°41’42”E, 320 m, 7 November 2005, fl., Guittou et al. 204 (P, TAN); Antsiranana II, Ramena, Andavakoera, forêt sèche sur tsingy, 12°20’25”S, 49°21’11”E, 233 m, 19 February 2007, fr., Guittou et al. 324 (P, TAN); Province de Diégo-Suarez [sic], montagne d'Ambre, ferme vétérinaire de Normandie, [dubious locality], 16–17 November 1944, st., Homolle 425 (P); Collines et plateaux calcaires de l'Ankarana (province de Diego-Suarez), [12°53’40”S, 49°11’18”E], December 1937–January 1938, MALAGASY EUPHORBIA SECTION PACHYSANTHAE Phytotaxa 159 (3) © 2014 Magnolia Press • 229 FIGURE 4. Euphorbia mandravioky. A. Habit. B. Bark. C. Leaves. D. Detail of a fertile branch showing two terminal cyathia without cyathophylls. E. Detail of a cyathium. F. Adaxial and abaxial views of cyathophylls. G. Young fruits. H. Mature fruit (note hanging position). I. Cross section of the fruit and the seed. A after Aubriot et al. 134 (P) and Aubriot et al. 108 (P), B–C after Aubriot et al. 107 (P), D–F after Service Forestier (Capuron) 11254 (P), G after Razafitsalama et al. 628 (P), H–I after Ratovoson 1244 (MO). st., Humbert 18919 bis (P); Plateau calcaire de l'Ankarana du nord entre Ambilobe et Anivorano, [12°52’10”S, 49°13’43”E], 200–350 m, 4–9 March 1951, fl., Humbert 25539 bis (P); Collines et plateaux calcaires de l'Ankarana du nord, [12°50’32”S, 49°14’38”E], 30–350 m, 24 January–29 February 1960, st., Humbert 32456 (P); SAVA, Daraina, village plus proche Tsaratanana, forêt d'Ampondrabe à 3 km au nord de Tsaratanana, 12°57’42”S, 230 • Phytotaxa 159 (3) © 2014 Magnolia Press AUBRIOT ET AL. 49°42’19”E, 23 September 2007, fl., fr., Randrianaivo 1483 (P, TAN); Montagne des Français, forêt d'Antaolanaomby, forêt sèche, 12°22’25”S, 49°21’11”E, 385 m, 22 March 2007, fr., Ratovoson 1244 (MO, P, TAN); Ramena, Andavakoera, forêt d'Andranonakomba, à 4 km au sud-est d'Andavakoera, 12°21’03”S, 49°21’29”E, 50 m, 5 December 2007, fr., Ratovoson et al. 1435 (P, TAN); Anstiranana, Ramena, Montagne des Français, partie Andavakoera, 12°20’44”S, 49°21’9”E, 214 m, 13 August 2004, fr., Razafitsalama et al. 628 (K, P, TAN); Pic des Orchidées, village le plus proche Andranomanity, canton de Mahavanona, [12°22’12”S, 49°21’E], 600 m, 13 September 1963, st., Service des Eaux et Forêts 718R64 (P). Conservation status:—With an Extent of Occurrence (EOO) of ca. 2850 km2, an Area of Occupancy (AOO) of 99 km2, and five severely fragmented subpopulations (one of which occurs within the Loky-Manambato protected area), Euphorbia mandravioky is assigned a preliminary status of “Endangered” [EN B1ab(i,ii,iii)+2ab(i,ii,iii)] based on the IUCN Red List Categories and Criteria (IUCN 2012). Euphorbia nusbaumeri X.Aubriot & Lowry, sp. nov. (Figure 5). E. haevermansii affinis est, sed cyathiis pedunculis longioribus, capsula sphaerica 1-seminali et laevi, semine pisiformi differt. Type:—MADAGASCAR. Province de Diego-Suarez/Antsiranana, sous-préfecture de Vohemar, commune rurale de Daraina, forêt d’Ambilondomba, 13°10’S, 49°39’E, 470 m, 27 January 2004, fr., Ranirison, Wohlhauser & Nusbaumer PR 321 (holotype P [P00751341]!; isotypes G [G00028186]!, K [K000014519]!, MO, TEF). Shrubs to small trees, to 6 m tall, monoecious; trunk to 18 cm in diameter, unbranched at the base; bark smooth, brown; secondary branches slender, forming a crown at the top of the trunk. White latex present in all organs. Leaves simple, alternate, grouped at the ends of the twigs, blade shiny, light green abaxially, dark green adaxially, fleshy, morphology very variable, elliptic to obovate, (4–)5–6(–8.5) × 2–3(–4), glabrous, primary vein light green, well impressed adaxially, secondary veins numerous, inconspicuous, base attenuate, margin entire, minutely serrate when young, thickened, undulate, apex mucronate; petiole small, (4–)6–8(–10) mm, light green to white, glabrous; stipules 2, gland-like. Cyathia pseudoterminal, 2 to 4 grouped together, less often solitary, functionally protandrous, cupuliform, slightly spreading, 0.6 cm in diameter when dry (including the glands), glabrous, peduncles 6–7 mm long; cyathophylls 2, deciduous, glabrous, spatulate, 0.6 × 0.4 cm, apex mucronate, subopposite (<0.5 mm from one another), inserted at the base of the cup. Glands 5, fleshy, contiguous, 3 × 2 mm, elliptic, recurved towards the cup, glabrous; surface light-green, weakly dotted when young, orange to reddish when mature; margin yellow-green, undulate. Interglandular bracts covering the cyathium cup when young, orbicular (2 × 2 mm), glabrous, green, margin laciniate. Staminate flowers numerous, grouped into 5 cymes, bracteoles numerous, filamentous, hyaline. Staminate flowers weakly exserted from the cyathium cup at maturity, pedicel 2 mm long, filaments thin, 1 mm long, anthers ca. 1 mm in diameter. Pistillate flower erect, inserted in the center of the cyathium, glabrous, style very short, stigmas 3, bifid, more or less recurved. Mature fruit (1 or)2–4 at the ends of the twigs, erect, peduncle green, ribbed; shiny green, unilocular, spherical, smooth, glabrous, ca. 1 cm in diameter, stigmas 3, persistent, minutely recurved, at the apex of the fruit. Seeds 1, pea-shaped, with two rounded basal lobes, 8 × 8 × 6 mm, apex pointed, testa smooth, green. Etymology:—This new species is named in honour of Louis Nusbaumer, who contributed greatly to the inventory project of the once poorly-collected Loky-Manambato region. His constant help to the first author while making preparations for fieldwork conducted in Madagascar, especially in the northeastern part of the island, was invaluable. Distribution and ecology:—Deciduous and semi-deciduous forests in the Daraina region of northeastern Madagascar, at 230–1000 m elevation. Additional specimens examined (paratypes):—MADAGASCAR. Forêt de Sahafary S./P. Diégo-Suarez, [12°34’S, 49°26’E], 2 December 1970, fl., Debray 1558-D (P); Province de Diego-Suarez/Antsiranana: Souspréfecture de Vohemar, commune rurale de Daraina, forêt de Solaniampilana-Maroadabo, 13°6’S, 49°35’E, 541 m, 5 February 2006, fr., Nusbaumer & Ranirison LN 2173 (G); Sous-préfecture de Vohemar, commune rurale de Daraina, forêt de Bekaraoka, partie nord, 13°6’S, 49°42’E, 230 m, 12 February 2004, fr., Nusbaumer & Ranirison LN 1156 (G, K, P); Sous-préfecture de Vohemar, commune rurale de Daraina, forêt de Solaniampilana-Maroadabo, 13°6’S, 49°35’E, 562 m, 2 February 2006, fr., Nusbaumer & Ranirison LN 1994 (G, P); SAVA, Vohemar, Andrafainkona, Ampisarahina, forêt dense sub-humide de moyenne altitude de Maromaniry, située à 5 km au nord d'Ampisarahina, 13°38’38”S, 49°32’51”E, 1090 m, 10 November 2007, fl., Randriambololomamonjy et al. 392 (MO, P, TAN). MALAGASY EUPHORBIA SECTION PACHYSANTHAE Phytotaxa 159 (3) © 2014 Magnolia Press • 231 FIGURE 5. Euphorbia nusbaumeri. A. Detail of a fertile branch showing four terminal cyathia. B. Leaves. C. Young cyathium with two cyathophylls seen from above. D. One of a pair of cyathophylls. E. Detail of a young cyathium and cyathophylls with the female flower still half included in the cyathium cup. F. Detail of a fertile branch showing three terminal mature fruits. G. Front view of a fruit and of a seed enclosed in the fruit. H. Ventral, lateral and dorsal views of a seed. A, C after Randriambololomamonjy et al. 392 (MO, P, TAN), B, F–H after Ranirison et al. PR 321 (G, P), D–E after Debray 1558-D (P). 232 • Phytotaxa 159 (3) © 2014 Magnolia Press AUBRIOT ET AL. Conservation status:—Euphorbia nusbaumeri, with an Extent of Occurrence (EOO) <500 km2, an Area of Occupancy (AOO) of 45 km 2, and 3 severely fragmented subpopulations (one of which occurs within the Loky Manambato protected area), is assigned a provisional status of “Endangered” [EN B1ab(i,ii,iii)+2ab(i,ii,iii)] based on the IUCN Red List Criteria (IUCN 2012). Notes:—Euphorbia nusbaumeri most closely resembles to E. haevermansii, but differs in having 1-seeded, unilocular fruits that are smooth and borne in groups of 2 to 4, whereas E. haevermansii bears 3-seeded, trilocular fruits that are deeply sulcate and solitary or borne in pairs. Moreover, the seeds of E. nusbaumeri are pea-shaped, whereas those of E. haevermansii are 3-angled, and the cyathia of E. nusbaumeri are borne on peduncles 6–7 mm long, whereas E. haevermansii has peduncles 4 mm long. Finally, the cyathophylls of E. nusbaumeri are directly inserted at the base of the cyathium cup, whereas those of E. haevermansii are inserted at the base of the peduncle (no cyathophylls or insertion traces are visible on the peduncle). Euphorbia pachysantha Baillon (1886: 624). Euphorbia monocephala Baker ex Denis (1921: 43), nom. illeg. Lectotype (designated here):—MADAGASCAR. Central Madagascar, without precise locality, fl., Baron 4437 (lectotype P [P00078061]!; isolectotypes K [K000185237]!, P [P00078062]!, [P00078063]!). Small to medium sized trees, 3–6(–15) m tall, monoecious, deciduous, pachycaulous, trunk to 50 cm in diameter, unbranched at the base; bark smooth; secondary branches slender and numerous, forming a crown at the top of the trunk, young branches rounded, greenish brown. White latex present in all organs. Leaves simple, alternate, grouped at the ends of the twigs, light green abaxially, blade dark green to glaucous adaxially, thin, usually lanceolate to elliptic (very variable in shape), always 2–3 times longer than wide, (4–)6–10(–14) × 2–3.5(–5) cm, glabrous, primary vein light green, well impressed adaxially, secondary veins light green, numerous, usually almost perpendicular to the primary vein, base attenuate, margin entire, thickened, apex strongly acuminate, rarely retuse; petiole (0.5–)1–1.5(–2) cm long, light-green, glabrous; stipules 2, gland-like. Cyathia pseudoterminal, usually solitary, sometimes 2 or 3 grouped at the top of the fertile twigs, functionally protandrous, broadly obconical, 0.8– 1 cm in diameter when dry (including the glands), glabrous, peduncles 2–4 mm long; cyathophylls 2 to 4, whitishgreen, deciduous, glabrous, elliptic to obovate, very variable in size, inserted at the base of the cyathium peduncle. Glands (4 or)5, stalk short (2 × 2 mm), fleshy, not touching one another, 3.5–5 × 1 mm (dry and excluding the stalk), crescent-shaped, with appendices recurved towards the cyathium cup, gland margins smooth. Interglandular bracts curved towards the cyathium cup, as long as wide (about 2 × 2 mm), circular, glabrous, greenish-yellow, fimbriate on the upper side. Staminate flowers numerous, divided into 5 cymes subtended and covered by interglandular bracts; cymes separated completely from one another by one (or more) encircling bracteoles. Staminate flowers well exserted from the cyathium cup at maturity, pedicels 2 mm long, filaments thin, 2 mm long, anthers <1 mm in diameter. Pistillate flower erect, inserted in the center of the cyathium, tricarpellate, stigmas 3, bifid, short, thin, recurved and brown. Mature fruit solitary, erect, glabrous, smooth; fruit unilocular or bilocular, with an evident globular lobe 1.4 cm in diameter when dry plus a smaller aborted lobe, hemispherical, less than 7 mm in diameter. Seeds unknown. Distribution and ecology:—Euphorbia pachysantha grows on soils derived from gneiss in humid forests and ravines in eastern Madagascar, in the vicinity of Lac Alaotra, near Toamasina, and south of Vatomandry, at 400– 800 m elevation. Additional specimens examined:—MADAGASCAR. Toamasina Province. Centre: Escarpements rocheux de la Mandraka, à la sortie des gorges (P.K. 70 de la route de Tananarive à Moramanga), [18°55’S, 47°50’5”E], 8 November 1957, fl., fr., Service Forestier (Capuron) 18409 (P); Menaloha (MEN-154), District d'Ambatondrazaka, [17°44’S, 48°28’E], September 1938, fl., fr., Cours 770 (P); Pentes à l'est du lac Alaotra, [17°33’25”S, 48°33’56”E], 800 m, October 1937, fl., Humbert 17573 (P); Anosivola (Manjobo) [Nosivolo (Mangoro)], [20°3’S, 48°8’E], 700 m, November 1911, fl., fr., Perrier de la Bâthie 9658 (K, P); Fianarantsoa Province. Mananjary, [21°14’18”S, 48°19’3”E], 400 m, December 1911, fr., Perrier de la Bâthie 9689 (P); Forêt orientale, près de Sevazy au S.W. de Vatomandry, [19°39’45”S, 48°31’59”E], December 1921, fl., Perrier de la Bâthie 14160 (P). MALAGASY EUPHORBIA SECTION PACHYSANTHAE Phytotaxa 159 (3) © 2014 Magnolia Press • 233 Conservation status:—Euphorbia pachysantha has an Extent of Occurrence (EOO) of ca. 16,100 km 2, an Area of Occupancy (AOO) of 54 km2, and is known from six fragmented subpopulations (none of which occurs within the protected area network). This species has not been collected in 50 years. Consequently, we have assigned a preliminary status of “Endangered” [(EN B2ab(i,ii,iii)] based on the IUCN Red List Categories and Criteria (IUCN 2012). Notes:—Considering that Rauh (1996) recently published detailed photos of a living specimen of Euphorbia pachysantha, we have refrained from including a line drawing as it would not have provided any new information. Acknowledgments The authors wish to thank the CNRE (Centre National de Recherche sur l’Environnement, Antananarivo, Madagascar), MNP (Madagascar National Parks) and the local office of the Missouri Botanical Garden (MO) in Antananarivo for assistance during fieldwork and for help with obtaining permits. We are much indebted to Louis Nusbaumer (G) and Laurent Gautier (G) for their advice and assistance in preparing fieldwork in northern Madagascar. We also wish to thank Agathe Haevermans (P) for the fine drawings and Zachary Rogers (MO) for performing some fruit dissections. Paul Berry is acknowledged for his invaluable advice and recommendations. We are grateful to the curators of the following herbaria for access to their collection: G, K, MICH, MO, P, TAN. Financial support for fieldwork was provided by the PPF MNHN “Taxonomie moléculaire: DNA Barcode & gestion durable des collections”, Sud-Expert-Plantes Programme # 382, and an ANR EVORANGE 6ème extinction grant (ANR-09-PEXT-011). 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