Wahlert, G. A., P. B. Phillipson, L. Nusbaumer & L. Gautier (2012). Cyphostemma darainense Wahlert & Phillipson (Vitaceae), a new species from northeastern Madagascar. Candollea 67: 277–283. In English, English and French abstracts.
Cyphostemma darainense Wahlert & Phillipson (Vitaceae), a new species from northeastern Madagascar, is described and illustrated. Recent floristic inventories in the Loky-Manambato region of northeastern Madagascar have highlighted the area as an important area of local endemism for plants. The new species was identified after survey of the collections for this genus in the Geneva herbarium and latter confirmed during the preparation of the treatment of Vitaceae for the “Catalogue of the Vascular Plants of Madagascar”. Observations about its ecology are also provided, its potential range is modeled using the statistical package “BIOMOD”, and its preliminary IUCN conservation status is given.
Introduction
The genera and species of Vitaceae of Madagascar were last treated by Descoings (1967). A recent taxonomic treatment of the Vitaceae for Madagascar Catalogue (2011) has shown northern Madagascar to be a center of diversity for the family, with 26 of the 53 native species occurring within the Antsiranana Province. While evaluating the species diversity of Cyphostemma (Planch.) Alston for this project, several specimens from the Daraina region were examined that did not fit the description of any of the known species from Madagascar.
Over the course of several years, intensive botanical exploration and vegetation studies of the patchwork of forests in the Daraina region, notably by the Conservatoire et Jardin botaniques de la Ville de Genève, in partnership with DBEV, Antananarivo University and Fanamby NGO, have resulted in the discovery of many new plant species in diverse families, (see list in Nusbaumer & al., 2010, and additional descriptions in Rakotoarinivo & Dransfield, 2010; Skema & Dorr, 2010; Callmander & Phillipson, 2011; Callmander & al., 2011; Jongkind & Gautier, 2011). The Daraina region was recently protected with a provisional and official status of Loky-Manambato Multiple Usage Forest Station (Station Forestière à usages Multiples = SFUM).
In addition to the taxonomic novelties resulting from botanical inventories, vegetation and ecological studies conducted in the Loky-Manambato region has provided a dataset enabling to predict species distribution. In particular, the potential distribution and environmental optimum of the new species described here was modeled using the “BIOMOD” statistical package (Thuiller, 2003; Thuiller & al., 2009). “BIOMOD” is a conservation management and climate change measurement tool which is largely used for predicting species distributions at a local to continental scale (Guisan & Thuiller, 2005; Lobo & al., 2010; Keenan & al., 2011; McMahon & al., 2011). “BIOMOD” allows the use of different statistical models resulting in a consensus prediction of distribution, potential niche, and the probability of presence of the species on a delimited surface (Thuiller & al., 2009). Data were obtained by recording plant occurrences along transects with measurements taken every 10 m across the ten main forest blocks of the Loky-Manambato region. In addition to recording the taxa, satellite images and a digital elevation model were used to compute the following environmental variables at a small scale: annual mean temperature, potential solar radiation, cloud cover during the dry season (April–November) and the wet season (December–March), slope, curvature, and distance to rivers. These data and the “BIOMOD” platform were used to generate predicted distribution and to evaluate the most important environmental variables influencing the distribution of a species in the area.
Cyphostemma darainense Wahlert & Phillipson, spec. nova(Fig. 1–4).
Typus: Madagascar. Prov. Antsiranana: Vohemar, Daraina, forêt d'Andranotsimaty, à 10 km au Nord-est de Daraina, 13°11′04″S 049°42′24″E, 182 m, 14.XI.2005, fr., Randrianaivo & al. 1308 (holo-: P; iso-: CNARP, MO [6028348], TAN).
Cyphostemma darainense Wahlert & Phillipson is similar to C. echinocarpa Desc., but differs by the acute apex of the stipule, the obovate leaflets with rounded or mucronate apices, and the shorter peduncle.
Plant a pachycaul, with a swollen, semi-succulent, bottleshaped trunk up to 2 m tall, with 1-few lianescent stems growing from the apex of the trunk. Stems up to 6 m long, subwoody, young stems sparsely pubescent; nodes slightly swollen, pubescent; stipules caducous, narrowly triangular, 3.5–5 × 0.7–1.1 mm, pubescent, margin ciliate, apex acute; young tendrils sparsely pubescent, apex bifid, subpersistent; mature tendrils becoming glabrous. Leaf compound, imparipinnate with (2-)3 pairs of lateral leaflets, 13–25 cm long (including petiole), 7–11 cm wide; rachis pubescent when young, becoming sparsely pubescent, extending 2–3 cm beyond the upper pair of lateral leaflets; petiole 4.5–8 cm long; lateral and terminal leaflets similar, obovate or rarely ovate or sub orbicular, 3–5.8 cm long, 2.2–4.2 cm wide, base cuneate, rounded, or truncate, apex rounded or obtuse, mucronate, mucro 1–3 mm long, margin finely denticulate, ciliate, young leaves densely pubescent, becoming sparsely pubescent or glabrous; petiolules 1–4 mm long, pubescent; primary vein visible on both surfaces, sparsely pubescent on lower surface, minutely pubescent on upper surface towards the base; secondary veins visible on lower surface, not clearly visible on upper surface, sparsely pubescent on lower surface, tertiary venation reticulate. Inflorescence a leaf-opposed, compound dichasial cyme, open, flat-topped, c. 7–10 cm wide, rachis sparsely pubescent, peduncle 3.5–7.5 cm long, bracteoles ovate to broadly triangular, c. 0.3 × 0.3 mm, margin ciliate. Flower bud cylindrical and slightly constricted near the middle, 1.8–2.5 mm long, 1.4–2 mm wide at the base, glabrous; pedicel 4–12 mm long, thickened near the calyx, sparsely pubescent to glabrous. Calyx a fused membranous flange, 0.4–0.6 mm tall, ciliate at the summit. Corolla pale yellow, petals four, linguiform, glabrous, 3–3.5 mm long, 1–1.5 mm wide at the base, 0.8–1, apex rounded, ± hooded, margin entire, with 6–10 parallel veins. Stamens four, oppositipetalous, 1.8–3.8 mm long, filament 1.7–2.1 mm long, anther dorsifixed, oblate, 0.5–0.7 × 0.5–0.7 mm; nectary glands four, alternipetalous, square to rectangular, 0.6–0.8 × 0.7–1.1 mm, fused to the base of the ovary. Ovary ovoid, 0.8–0.9 × 0.7–0.8 mm, glabrous, style cylindrical, glabrous, c. 0.6 mm long. Fruit a berry, subspheroid, green, c. 2 × 1.5 cm, glabrous. Seed reniform-obovoid, beaked, with a raphe, c. 13 × 7 mm.
Etymology. — The specific epithet refers to the locality of Daraina in the central part of the Loky-Manambato region which is the only known region of occurrence for the new species.
Distribution. — The species is only known from the forests of Loky-Manambato. Fifty-eight individuals were observed among more than 54,000 plant occurrences identified during a vegetation study of the region. It is frequent in several forests subareas of this region, including: Ampondrabe, Bekaraoka, and Solianampilana, and less frequently in Ankaramy, Bobankora, and Antsahabe.
Habitat and ecology. — Cyphostemma darainense grows primarily in dry forests or in ripicolous vegetation within dry forests, and uncommonly to rarely in mesophyllous, arbustive saxicolous, or sclerophyllous forest types. It occurs on thin substrates, generally among stones or on rocky outcrops. The species was observed at low elevations, between 100 and 550 m, on level ground or slopes, but never on ridge crests. The species does not grow in sites that do not provide stability for the swollen, semi-succulent trunk. The absence of the species from crests and steep slopes may indicate that it is susceptible to windthrow. Cyphostemma darainense grows in forests with canopies reaching 8 to 10 m, with emergent trees reaching 10 to 14(-18) m, with a sparse arbustive strata 2 to 4.5 m high, and a sparse suffrutescent strata less than 1 m high.
The most frequent species recorded together with C. darainense in vegetation surveys are, in decreasing abundance: Drypetes perrieri Leandri, Cynometra commersoniana Baill., Dialium occidentale subsp. septentrionale Du Puy & R. Rabev., Grevea madagascariensis Baill., Dracaena reflexa Lam., Strychnos decussata (Pappe) Gilg, Ehretia cymosa Thonn., Baudouinia sollyaeformis Baill., Dracaena xiphophylla Baker, Droceloncia rigidifolia (Baill.) J. Léonard, Mallotus oppositifolius (Geiseler) Müll. Arg., and Gyrocarpus americanus subsp. tomentosus Kubitzki.
Potential distribution. — Results from modeling the potential distribution of Cyphostemma darainense show the species to have an affinity with the environmental conditions present in the eastern forests of Loky-Manambato (Fig. 5). The three most important environmental variables that appear to delimit its distribution are: a) annual mean temperature less than 19°C, b) slopes greater than 28° (at higher temperatures), and c) cloud cover less than 20% during the dry season.
Conservation status. — With an “Extent Of Occurrence” (EOO) of 551 km2, an “Area Of Occupancy” (AOO) of 76 km2, and 8 subpopulations, 5 of which are in the Loky-Manambato protected area, C. darainense is assigned a preliminary status of “Endangered” (EN) following IUCN (2001) (calculation following Moat, 2007, and Callmander & al., 2007).
Paratypi. — Madagascar: Antsiranana Province, Vohemar District, Daraina, Mahatsara, Ambilondambo (Ambilondamba) à 8 km au Nord de Daraina, 13°09′45″S 049°38′49″E, 326 m, 17.XI.2005, fr., Be & al. 292 (CNARP, G, MO, P[2 sheets], TAN); Ampisikina, Tsaratanana, forêt d'Ampondrabe, à 1 km au Nord ouest du village d'Ambaribe, 12°58′18″S 049°41′57″E, 200 m, 4.XI.2005, fr., Rakotonandrasana & al. 968 (CNARP, MO, P, TAN); Daraina, Befarafara, forêt de Solanampilana, Ankoakala, à 2 km au Sud de Befarafara, 13°05′26″S 049°34′ 32″E, 100 m, 15.XI.2005, fr., Rakotonandrasana & al. 987 (CNARP, G, MO, P, TAN); Ampisikina (Ampisikinana) Soatanana, Ambarilao, forêt d'Ampondrabe, 12°57′39″S 049°42′ 31″E, 175 m, 5.XI.2005, fl., Ratovoson & al. 1060 (MO, P, TAN); Daraina, forêt d'Ankaramy, à 1330 m du point côté 215, au 123°, 13°17′30″S 49°40′47″E, 330 m, 21.XII.2005, fr., Ranirison & Nusbaumer 1037 (G, K, MO, P, TEF).
Fig. 1.
Cyphostemma darainense Wahlert & Phillipson. A. Inflorescence; B. Flower showing corolla and fused, flange-like calyx; C. Stamen and nectary glands; D. Fruit; E. Ovary; F. Petal ; G. Immature leaflet ; H. Node and stipules.
[Ratovoson & al. 1060, MO] [Drawn by R. L. Andriamiarisoa]
Fig. 2.
Cyphostemma darainense Wahlert & Phillipson. A. Dried fruit ; B. Leaflet ; C. Infructescence.
[Be & al. 292, CNARP] [Drawn by R. L. Andriamiarisoa]
Fig. 3.
Field photograph showing fresh leaves and mature fruits of Cyphostemma darainense Wahlert & Phillipson.
[Ranirison & Nusbaumer 1037, G] [Photo : L. Nussbaumer]
Fig. 4.
Field photograph showing pachycaulous habit of the trunk of Cyphostemma darainense Wahlert & Phillipson.
[Ranirison & Nusbaumer 1037, G] [Photo : L. Nussbaumer]
Fig. 5.
Map of Loky-Manambato area showing actual distribution of Cyphostemma darainense Wahlert & Phillipson (red dots), potential distribution (black shading), and area not predicted for its distribution (white). [Forest acronyms: Abd: Ambilondamba, Ank: Ankaramy, Apb: Ampondrabe, Atb: Antsahabe, Atd: Ambohitsitondroina, Atg: Antsaharaingy, Bek : Bekaraoka, Bin : Binara, Sol : Solaniampilana].
Table 1.
Main differences between Cyphostemma darainense Wahlert & Phillipson and C. echinocarpa Desc.
Acknowledgements
We are grateful to the curators of the following herbaria for access to their collections: G, MO, P, and TAN. We also thank Roger Lala Andriamiarisoa (Antananarivo, Madagascar) for providing the illustrations. Two anonymous reviewers provided valuable comments that improved the manuscript. We appreciate the comments of Roy Gereau (MO) that improved the diagnosis. Financial support was provided to GAW and PBP through a grant from the U.S. National Science Foundation (0743355). Support to LN and LG was provided by the Conservatoire et Jardin botaniques de la Ville de Genève, the University of Geneva, Conservation International (CBC fund), the Malagasy NGO Fanamby, the Fondation Jean-Marcel Aubert, and the Vontobel Stiftung; we would like to thank all collaborators of these institutions.
