Psychotria veillonii Barrabé, 2014

Barrabé, Laure, 2014, Four new species of Psychotria (Rubiaceae) from New Caledonia, including one presumed to be extinct, Phytotaxa 173 (2), pp. 101-116 : 113

Psychotria veillonii Barrabé , sp. nov. ( Fig. 8 )

This species is similar to Psychotria cardiochlamys ( Baillon 1879: 287) Schlechter (1906: 261) , from which it differs principally by the pyrenes, 9.5 × 6.5 × 2.5–3.5 mm, with large ribs (vs. 6–7 × 2–2.5 × 1.5–2 mm, smooth, i.e. without ribs, in P. cardiochlamys ).

Type: — NEW CALEDONIA. Grande Terre, Province Nord: massif de la Tiébaghi, sud-est du Dôme, petit thalweg, relevé Tieb 18, maquis arbustif dominé par Araucaria rulei , sol ferrallitique gravillonnaire de colluvions, 450 m, 22 July 1996, G. Dagostini & J.-M. Veillon 71 (holotype P-00752149!, isotype! NOU-032742!) .

Shrub; bark brown when dry, glabrous, vertically rugulose, horizontally striate especially on young parts; young shoots, petioles and terminal vegetative buds glabrous. Stipules enclosing vegetative and floral buds, orbicular, 5.5–6 × 6–7 mm, round at apex, with margins entire, slightly undulate, colour unknown, glabrous, deciduous; colleters present. Leaves clustered at ends of branches; petioles sometimes with horizontal striations, 0.6–1.3 cm long, 1–1.5 mm thick, with an articulate base, plano-convex; blades spathulate to oblanceolate, 4.6–9 × 0.7–2.2 cm, acute at apex, tip obtuse to round, acute at base, margins entire and revolute, blade chartaceous, grayish-green on both sides when dry or sometimes reddish, glabrous on both sides; venation glabrous, with midvein raised throughout, black or dark on abaxial side when dry; secondary veins 8–13 on each side, spaced at 3–9 mm, at 50° angle with the midvein, depressed on adaxial side, slightly raised on abaxial side; tertiary venation obscure on both sides. Inflorescences erect, capitate, tri-flowered, glabrous, sessile. Bracts inconspicuous, hidden by enclosing stipules, otherwise unknown. Flowers partially known, 4-merous, erect, sessile, style heterogeneity unknown; flower buds obovoid to spathulate. Hypanthium turbinate, 1 × 2.5 mm, smooth, colour unknown, glabrous; nectary disk entire, circular, to 1.5 mm in diameter, glabrous. Calyx chartaceous, colour unknown, glabrous throughout; tube to 0.5 mm long, colleters lacking; lobes triangular, 0.75 × 1.25 mm, acute at apex, erect, margins entire. Corolla actinomorphic, tubular, texture and colour unknown, glabrous outside, inside unknown. Stamens unknown. Style filiform, 8.5 × 0.1 mm. Stigma bilobed. Fruits ovoid, 10 × 8 mm, smooth, colour unknown, glabrous. Pyrenes plano-convex, ovoid, 9.5 × 6.5 × 2.5–3.5 mm, acute and bifid at apex, round and emarginate at base; dorsal side convex, wrinkled, 5-ribbed, ribs strongly prominent; ventral side flat, slightly wrinkled, with a wide ventral excavation and a thin raised median crest, margins grooved; pregermination slits lacking, basal aperture present. Endosperm unknown.

Distribution and habitat: — Psychotria veillonii Barrabé (this publication) occurs in ‘maquis minier’ on ultramafic substrates on the Tiébaghi Massif, at 450 m ( Fig. 3 ).

Phenology: —The single herbarium collection was made in July with flower buds, old flowers, and fruits.

Etymology: —This species is named for Jean-Marie Veillon, a botanist who worked at IRD Nouméa between 1964 and 1999, and who has contributed significantly to our knowledge of the New Caledonian flora, including through his taxonomic revisions of Dilleniaceae , Oncothecaceae , and Pittosporaceae .

Affinities: — Psychotria veillonii belongs to the ‘ cardiochlamys’ subclade (Barrabé 2013), which includes one other species, P. cardiochlamys . These species are characterized by leaves 2–10 cm long, cordate stipules, capitate, tri-flowered inflorescences, fruits 0.5–1 cm in diameter, and pyrenes without pregermination slits. Characters that distinguish between P. veillonii and P. cardiochlamys are given in the diagnosis and no further differences can be given at present because the single known collection of P. veillonii is incomplete. Both species are found on ultramafic substrates; P. veillonii from the Tiébaghi Massif, north of Koumac ( Fig. 3 ), whereas P. cardiochlamys occurs throughout the ultramafic unit of the south-east of New Caledonia and on all the isolated massifs along the north-western coast.

Conservation assessment according to the IUCN Red List categories and criteria: —Present evidence indicates that Psychotria veillonii is confined to the massif of Tiébaghi. This species was apparently rare in 1996 when just one mature individual was collected by Gilles Dagostini and Jean-Marie Veillon, during an evaluation of the impact of reopening a mining site on the massif ( Dagostini et al. 1997, Jaffré et al. 1998a). This collection (Dagostini & Veillon 71) was made at what is now the centre of this mining site, and all the vegetation there has now been destroyed. Five other recent botanical expeditions have been made to the massif, but all failed to find this species again (pers. obs. & pers. comm. from members of the Botany Laboratory of IRD Nouméa). Although it is possible that P. veillonii might occur on other ultramafic massifs along the north-western coast, such as Poum or Kaala, it appears at present, to be, or to have been, a micro-endemic on Tiébaghi. Because of the destruction of the single locality from which this species is known, P. veillonii can be considered as possibly extinct: EX.

Figures

FIGURE 3. Distribution map of the four new Psychotria species in New Caledonia. Ultramafic substrates are shaded in gray.

FIGURE 8. Psychotria veillonii Barrabé. A. Branches with young inflorescences; B. Detail of the young inflorescence; C. Fruit apex; D. Fruit; E. Dorsal face of the pyrene; F. Ventral face of the pyrene; G. Lateral surface of the pyrene; H. Cross section of the pyrene. Drawn by Michèle Magat.