A revision of Ventilago (Rhamnaceae) in New Caledonia and Vanuatu with notes on dyeing properties

: The climbing genus Ventilago Gaertn. ( Rhamnaceae ) is revised in New Caledonia and Vanuatu. The de- scription of V. pseudcalyculata Guillaumin was based on four gatherings (syntypes). The name is lectotypified with a specimen from Lifou, and the species is now considered to be restricted to the Loyalty Islands, while the specimens from Grande Terre (the main island of New Caledonia) are treated as a new species, V. tinctoria Cahen, Toussirot & Pillon. A total of four endemic species are therefore recognized in New Caledonia: V. buxoides Baill., V. neo­ caledonica Schltr. and V. tinctoria from Grande Terre and V. pseudocalyculata from the Loyalty Islands. The plants from Vanuatu, often identified as V. neocaledonica , are treated here as a new species, V. vanuatuana Cahen, Toussirot & Pillon, endemic to that archipelago.


Introduction
Rhamnaceae are represented by about ten species in seven genera in New Caledonia . The most complete overview for New Caledonia is a short summary of the family with identification keys and description of new species by Guillaumin (1926). A short description of the family and a key to species was also included in Flore analy tique et synoptique de la NouvelleCalédonie (Guillamin 1948a). Recent work has included the lectotypification of Emmenosperma pancherianum Baill., a species once thought to be endemic to New Caledonia and discovered in 2005 in Queensland (Bean 2013). A molecular phylogenetic study (Hopkins & al. 2015) has indicated that Alphitonia erubescens Baill. and A. xerocarpa Baill. were misplaced in the genus Alphitonia Reissek ex Engl. and were accommodated in a newly described genus Jaffrea H. C. Hopkins & Pillon, endemic to New Caledonia. This study also included the lectotypification of these two species names, along with A. neo caledonica Schltr. A phylogenetic and biogeographic  Cahen & al.: A revision of Ventilago in New Caledonia and Vanuatu analysis of Alphitonia and of related Emmenosperma F. Muell., Granitites Rye and Jaffrea supports the currently applied taxonomy in these genera (Hauenschild & al. 2018). The genera Colubrina Rich. ex Brongn. (Johnston 1971) and Rhamnella Miq. (= Dallachya F. Muell.;Smith 1943) are each represented by a single non-endemic species: Colubrina asiatica (L.) Brongn. and Rhamnella vitiensis (Benth.) A. C. Sm.
No taxonomic treatment of Ventilago Gaertn. or Goua nia Jacq. in New Caledonia has been published since Guillaumin (1926Guillaumin ( , 1948a. However, recent work on Ventilago in neighbouring regions was published (Cahen & Utteridge 2017), and the closely related genus Smythea Seem., which occurs in Vanuatu, was revised (Cahen & Utteridge 2018). Ventilago and Smythea are the only members of tribe Ven tilagineae Hook. f., unique in Rhamnaceae in its members' fruits having a pronounced apical appendage. Generic delimitation between Ventilago and Smythea is based on the shape of the seed chamber of the fruit: conspicuously globose and clearly differentiated from the wing in Ventilago, compressed and gradually flattened into the wing (when present) in Smythea (Cahen & Utteridge 2018). Ventilago is a genus of about 30 species of tropical climbing shrubs, lianas and, rarely, small trees, absent from the Neotropics, easily recognized by their fruits having the combination of an oblong wing-like apical appendage and a conspicuously globose seed chamber (Suessenguth 1953;Medan & Schirarend 2004;Cahen & Utteridge 2018). The traditional use of Ventilago plants as a source of dyes in New Caledonia and Vanuatu and potential further uses were documented in Blanc (2008), Cardon (2007) and Cardon & al. (2010). Three species of Ventilago were considered to be native to New Caledonia : V. buxoides Baill., V. neo caledonica Schltr. and V. pseudocalyculata Guillaumin. An additional species, V. tinctoria Cahen, Toussirot & Pillon is recognized here. The abundance of ultramafic soils in New Caledonia, which cover one-third of the surface of Grande Terre (the main island) acts as an ecological filter affecting species composition, with plants having to face high Mg:Ca ratios, high metal concentrations, poor fertility and often limited water availability (Pillon & al 2010). Despite this, species of Ventilago appear to grow indiscriminately on both ultramafic and non-ultramafic substrates in New Caledonia.
The genus is also present in Vanuatu, where the material has often been determined as Ventilago neocaledonica (e.g. Guillaumin 1948b), but is identified here as belonging to a distinct endemic species: V. vanuatuana Cahen, Toussirot & Pillon (see Remarks for V. vanuatuana and Notes on dyeing properties). Other Rhamnaceae genera reported to occur in Vanuatu are Colubrina, Gouania, Rhamnella and Smythea (Wheatley 1992). While some species in these genera were enumerated or described by Guillaumin (1931), Wheatley (1992) and Ramon & Sam (2015), no comprehensive taxonomic treatment of Rham naceae has been published for Vanuatu. The archipelago is located very near New Caledonia, with Aneityum just over 200 km northeast of the Loyalty Islands and 350 km from Grande Terre, and in some cases phytogeographic relationships between the two archipelagos are strong (Lowry 1989), despite most plants possibly coming to Vanuatu from the northwest from Malesia via New Guinea and the Solomons, and from Fiji (Ramon & Sam 2015). Given their geographic proximity and because of previous misidentifications of Vanuatu material as V. neo caledonica, the genus is advantageously studied for both areas together and its taxonomy is revised here for both New Caledonia and Vanuatu.

Material and methods
Herbarium specimens from CANB, K, L, MPU, NOU, P and Z were studied; an exclamation mark (!) is used to show that a specimen has been seen, whereas "image!" is used to show that an image of the specimen has been seen. Hair density terms are defined as follows: sparse when hairs are scattered enough not to touch when pressed toward each other, abundant when hairs are close enough to touch if pressed toward each other, dense when hairs are so close to each other that they hide the surface of the organ they grow on. Leaf anatomy terms used are from Hickey (1979) and other morphology terms follow Beentje (2010). GeoCat (Bachman & al. 2011) was used to calculate Extent of Occurrence (EOO). All examined specimens appear in the Appendix (see Supplemental content online), sorted alphabetically first by species and then by collector's name.

Notes on dyeing properties
Natural dyes are an integral component of cultural heritage worldwide, and the use of plant-derived dyes in the Pacific Ocean is the subject of ongoing research (e.g. Cardon 2007;Cardon & al. 2010: Toussirot & al. 2012, 2014. The phytochemical study of Ventilago species shows that the colours obtained from them are often due to a rich mixture of quinones (Cardon & al. 2010). Three anthraquinones in particular, emodin, physcion and chrysophanol, are found in the bark and roots (Blanc 2008;Toussirot 2014).
Studies conducted with the University of New Caledonia examined the dyeing and biological properties of the Ventilago species present in New Caledonia and Vanuatu (Blanc 2008;Cardon & al. 2010;Toussirot 2014). A climber from Vanuatu, named laba (Apma language, central Pentecost) is of great cultural significance in some islands of north-central Vanuatu, where the bark of its root is used to prepare the red dye of ceremonial mats. Bourdy & Walter (1986) described its use in Pentecost and had already noted the need for an in-depth taxonomic as well as ethnological study of this plant. The laba climber was at Willdenowia 50 -2020 the time identified as V. neocaledonica. However, significant colour differences were observed following dyeing tests carried out with different species (including among the species from New Caledonia, Fig. 8). The experimental protocols of these tests, including the mordanting methods and types of fibres used, as well as colorimetric and colour absorption measurements, are documented by Blanc (2008). Furthermore, subsequent analyses of the chemical profile of the specimens revealed qualitative and quantitative differences in their anthraquinone composition (Blanc 2008). The differences in colour and in quinone composition suggested that laba and V. neocale donica could be different species of Ventilago, and at this stage it was hypothesized that laba was V. vitiensis A. Gray rather than V. neocaledonica (Blanc 2008;Cardon & al. 2010). The taxonomic work presented here shows that laba is actually morphologically different from both V. neocaledonica and V. vitiensis and represents a distinct, hitherto undescribed species: V. vanuatuana.
This shows the potential benefits of interdisciplinary scientific research allowing analyses to complement one another. In this case, the study of the traditional use of dyes eventually led to the hypothesis of an undescribed species, which was confirmed here by study of herbarium specimens. Alternatively, improved taxonomic knowledge could refine studies of the traditional uses of these plants, for example by determining whether separate species previously believed to be the same have slightly different properties and therefore uses.

Key morphological characters
All species of Ventilago in New Caledonia and Vanuatu are woody climbers, sometimes growing as scandent shrubs, and are easily recognized when in fruit, as the fruits have a distinct wing-like apical appendage and a conspicuous, globose basal portion enclosing the seed chamber ( Fig. 4A, K; Fig. 6A, K). These characters help distinguish Ventilago species from all other Rhamnaceae genera occurring in the region: species of Alphitonia in New Caledonia and Vanuatu are all trees or shrubs with unwinged capsular fruits; Emmenosperma pancherianum is a shrub with capsular fruits and red seeds persisting on the pedicel after the pericarp has fallen; species of Jaffrea are trees and shrubs with conical flowers and late-dehiscent beaked fruits; Rhamnella vitiensis is a shrub with flowers in umbel-like cymes, and drupaceous fruits. Among the climbing genera, Colubrina asiatica (occasionally scandent) is distinct in the 3-seeded capsules with the outer pericarp irregularly breaking away and leaves with only 2 or 3 secondary veins (vs 4 -8 in Ventilago); Gouania is distinct in the presence of tendrils and fruits that are 3-winged schizocarps; Smythea lanceata is distinct in the crustaceous inflated wingless fruits (see Remarks for V. vanuatuana for further distinguishing characters). Morphological differences between Alphitonia, Emmenosperma and Jaffrea are discussed in Hopkins & al (2015) and genus-level morphological descriptions in Rhamnaceae are available in Medan & Schirarend (2004).

Inflorescences and flowers
In New Caledonia and Vanuatu, Ventilago flowers are arranged in cymes congested into fascicles ( Ventilago neocale donica can be distinguished from V. pseudo calyculata, V. tinctoria and V. vanuatuana in the inflorescence rachis, pedicels and abaxial surface of the calyx being glabrous to densely hairy (the hairs may be close enough to touch each other but are usually not so close as to hide the surface they grow on) vs almost always densely hairy (the hairs are so close to each other that they hide the surface they grow on). Ven tilago vanuatuana differs from V. pseudocalyculata and V. tinctoria in the indumentum of mostly spreading hairs on most parts of the plant, including the inflorescence rachis, pedicels and abaxial surface of the calyx ( . The dimensions of the wing are quite homogenous among species of the area (from c. 3 × 0.7 cm in V. buxoides to c. 3.5 × 0.8 cm in V. neocaledonica and V. pseudocalyculata). The only species with glabrous fruits are V. buxoides and V. neocaledonica, which are distinguished from each other in leaf and inflorescence characters (see above). All other species have densely hairy fruits, and V. vanuatuana is recognized in the hairs being mostly spreading (vs mostly appressed antrorse in V. pseudocalyculata and V. tinctoria). The fruit wing of V. pseudocalyculata is usually slightly curved and often ± trullate, distinctly narrower at the base, vs oblong in all other Ventilago species in the area. The species is further distinguished from V. tinctoria in the pedicel being usually swollen in fruit, gradually widening into the calyx, vs remaining slender in fruit, suddenly expanding into the calyx (Fig. 4K).  Guillaumin (1926).

The species of Ventilago in New Caledonia and Vanuatu
Description -Woody climber, to at least 4 m long. In dumentum sparse at base of branchlets, dense at distal end of branchlets and inflorescence rachis, hairs mostly whitish to sometimes fulvous, straight to slightly curved, mostly spreading. Branches slender, terete, smooth; branchlets often deeply ridged. Stipules fugaceous, though often persisting past flowering at distal end of branchlets, c. 1 mm long, narrowly deltoid to subulate. Leaves: petiole 1 -2 mm long, densely hairy; lamina dark green, shiny adaxially, broadly to narrowly ovate, 0.5 -3.5 × 0.3 -2 cm, subcoriaceous, subglabrous, sparsely hairy abaxially along primary vein, base usually slightly asymmetric, rounded to cordate, margin entire or broadly crenate to serrate, obscurely near base, serrations topped by callosities, apex rounded, often notched; secondary veins 4 -8, often not readily discernible from tertiary veins, remaining separate near margin or joining each other and forming loops near margin; tertiary venation not conspicuously scalariform. Inflorescence of cymes congested in fascicles in axils of leaves, fascicles sometimes arranged in racemiform thyrses when leaves subtending fascicles are fugaceous, flowers up to 6 per fascicle when in bud, usually only 1 left per fascicle by anthesis, racemiform thyrses usually less than 2 cm long. Flowers bisexual, c. 3 mm wide; pedicel c. 2 mm long when fully developed, pedicel and abaxial side of hypanthium sparsely hairy, with hairs spreading to appressed, white, straight to slightly curved, c. 0.1 mm long; sepal lobes 5, triangular, c. 1.2 mm long, adaxially keeled with an apical protuberance; petals 5, obcordate, c. 0.9 mm long, glabrous, base clawed, apex notched; stamens 5, each opposite and enclosed by a petal, filaments c. 0.7 mm long, anthers dorsifixed; disk subpentagonal, filling hypanthium, fleshy, smooth, glabrous; ovary immersed in to sometimes more than ½ exserted from disk, slightly hairy at level of exsertion from disk, glabrous distally, locules 2; style 2-fid. Fruit glabrous, with a conspicuous globose basal portion enclosing seed chamber and a distinct wing-like apical appendage, oblong, reaching c. 3 × 0.7 cm at maturity; apex rounded with style remains forming a distinct mucro; persistent calyx annular at base of fruit to slightly cupular and enclosing less than ¼ of globose part of fruit.
Distribution and ecology -This species is found in scrubland (maquis) and possibly forest at low elevation Willdenowia 50 -2020 on the western side of New Caledonia, from Mt Mou and the Tontouta valley to Île Art. It has been collected on ultramafic substrate, probably on serpentine in most cases. Fig. 1.     Guillaumin (1911), non Gaertn.

Conservation status
Description -Woody climber, to at least 3 m long.
Indumentum very sparse to sometimes dense at distal end of branchlets, inflorescence rachis and calyx, hairs mostly whitish to sometimes fulvous, slightly curved, mostly appressed antrorse, hairs usually denser on calyx.
Distribution and ecology -This species is widespread across the main island of New Caledonia, collected on both ultramafic and non-ultramafic substrate, in maquis, dry forest and rainforest. Fig. 2.
Conservation status -This relatively widespread spe- Remarks -Ventilago neocaledonica is recognized by its glabrous fruits. It most resembles V. tinctoria in the flower fascicles in racemiform thyrses, often arranged in panicles, and ovate leaf shape, but differs in the glabrous fruits, the sparser indumentum throughout, smaller leaves with a sometimes serrated margin and calyx usually enclosing more of the globose part of the fruit. Ventilago buxoides also has glabrous fruits, but has smaller leaves with a notched apex and open flowers and fruits most often inserted singly in the axils of persistent leaves.

Ventilago pseudocalyculata
Distribution and ecology -This species has been collected only in the Loyalty Islands, on Lifou and Maré, in forest or forest edge on limestone. It may be present on other Loyalty Islands (Ouvéa and Tiga). Fig. 3. Remarks -Ventilago pseudocalyculata resembles V. tinctoria from Grande Terre in the usually dense and mostly appressed antrorse hairs of branchlets, petioles, inflorescence and fruit and in the (sub-)entire leaf margin. It differs in the usually slightly curved fruit wing, often distinctly narrower at the base (vs oblong in V. tinc toria), the usually larger and more broadly ovate leaves, with a symmetric and rounded base (vs slightly asymmetric and cuneate base), and the pedicel usually swollen in fruit, gradually widening into the calyx (vs suddenly expanding into the calyx).
In the protologue, Guillaumin (1926) cited four gatherings but no herbarium locations: Pancher s.n. (Port Saint-Vincent), Balansa 528 (bord de la Rivière des Français), Balansa 1036 (bords du Kouétou-Kouéta) and Deplanche 62 (Lifou). In P, where Guillaumin worked, one specimen of Balansa 1036, one of Balansa 528, two of Deplanche 62 and one of Pancher 5746 (Port Saint Vincent) bear the name "Ventilago pseudocalyculata Guillaum" and Guillaumin's signature, one of Deplanche 62 also bears the handwritten "type" in Guillaumin's hand and is therefore chosen as the lectotype. Deplanche 62 is the only one of Guillaumin's syntypes that taxonomically belongs to V. pseudocalyculata. Pancher s.n., Balansa 528 and Balansa 1036 are all specimens of V. tinctoria.  -Ventilago pseudocalyculata sensu Guillaumin (1926Guillaumin ( , 1948a, Blanc (2008), Cardon & al (2010, omnia pro parte, excluso lectotypo. Diagnosis -Ventilago tinctoria is most similar to V. pseudocalyculata in the hairy fruits, in the usually dense and mostly appressed antrorse hairs of the branchlets, petioles, inflorescence and fruit, and in the (sub)entire leaf margin, but it differs in the oblong fruit wing (vs usually slightly curved and tapering at base in V. pseudocalycu lata), usually smaller and more narrowly elliptic leaves (3 -11.5 × 1.5 -5.5 cm in V. tinctoria vs 5 -13 × 2.5 -8.5 cm in V. pseudocalyculata), usually slightly asymmetric and cuneate at the base (vs symmetric and rounded in V. pseu docalyculata), and in the pedicels remaining slender in fruit and suddenly expanding into the calyx (vs gradually widening into the calyx in V. pseudocalyculata).
Distribution and ecology -This species has been collected in scrubland (maquis) and forest on ultramafic substrate in New Caledonia in the south and the eastern side of Grande Terre and on Île des Pins. Fig. 5.
Etymology -The specific epithet refers to the dyeing properties of this species (Blanc 2008;Cardon & al. 2010, cited as Ventilago pseudocalyculata).
Conservation status -Because its ecology and distribution are still imperfectly understood, this species has been evaluated as Data Deficient (DD)  Remarks -Ventilago tinctoria differs from all other Grande Terre Ventilago species (V. buxoides and V. neo caledonica) in its hairy fruit. It resembles V. pseudocaly culata of the Loyalty Islands, but differs in having an oblong fruit wing (Fig. 4A, K), usually smaller and narrower leaves that are slightly asymmetric and cuneate at the base (Fig. 4A, B), and slender pedicels that suddenly expand into the calyx (Fig. 4K). Three of the four gatherings that Guillaumin cited in the protologue of Ventilago pseudocalyculata were collected in Grande Terre and are now recognized as V. tinc toria. The fourth gathering, Deplanche 62, from Lifou, is designated here as the lectotype of V. pseudocalyculata (see Remarks for V. pseudocalyculata). Most herbarium material of V. tinctoria had previously been identified as V. pseudocalyculata, following Guillaumin (1926), but the Grande Terre specimens are morphologically distinct from those of Lifou, and V. pseudocalyculata as recognized here seems to be restricted to the Loyalty Islands.    Gray.
Diagnosis -Ventilago vanuatuana most closely resembles V. tinctoria in the hairy fruits with an oblong wing and in the flower fascicles being in racemiform thyrses, often arranged in panicles, but it differs in its narrower leaves with a crenate to serrate margin (vs margin entire, obscurely repand in V. tinctoria) and hairs of branchlets, petioles, inflorescence and fruit mostly spreading (vs hairs mostly appressed antrorse in V. tinctoria).
Distribution and ecology -This plant has been collected in forests in Vanuatu, on the islands of Santo, Malekula, Pentecost, Éfaté and Anatom. It probably occurs on other islands of the archipelago. Fig. 7.
Etymology -The plant is named after the country in which it is endemic, Vanuatu.
Conservation status -The distribution of this species is incompletely known because there are still few botanical collections from Vanuatu. The ecology is not well known, and it is not known if there are important threats. The spe-