Psychotria ireneae 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 : 106-109

Psychotria ireneae Barrabé , sp. nov. ( Figs. 4 , 5 )

This species is similar to Psychotria trisulcata ( Baillon 1879: 289) Guillaumin (1930: 35) , from which it differs principally by the entirely bright green and smooth leaves (vs. olive-green, whitish-variegate, and papillose on both sides of the blade in P. trisulcata ), and the pyrenes, 15–19 × 10–12 × 5–6 mm (vs. 12.5–14 × 5–6 × 3.5–4 mm).

Type: — NEW CALEDONIA. Grande Terre, Province Nord: Vallée de la Tchamba, exploitation Létocart , bord de piste, lisière de forêt dense humide, schistes, couche humifère épaisse, 520 m, 21°20’00’’S, 165°14’02’’E, 13 January 2009, L. Barrabé, D. & I. Létocart & A. Morignat 831 (holotype P!, isotypes MO!, NOU-033929!, NOU-033930!, S!) .

Fastigiate shrub, densely and regularly branched, 1–5 m tall; bark yellow, pale brown to dark brown when dry, glabrous, smooth; young shoots, petioles, and terminal vegetative buds glabrous. Stipules sheathing, broadly triangular, 1–2.5 × 1–3.5 mm, obtuse to apiculate at apex, with margins entire and slightly undulate, green, glabrous, deciduous; colleters not seen. Leaves regularly spaced on branches; petiole smooth, 0.2–2.5 cm long, 0.5–1 mm thick, plano-convex; blades elliptic to obovate, 2.7–9.6 × 0.9–4.3 cm, acuminate with an obtuse point at apex, acute and weakly decurrent at base, margins entire and narrowly revolute, blades chartaceous, discolorous, darker on adaxial side, glabrous throughout; venation glabrous, with midvein channelled on adaxial side and raised on abaxial side; secondary veins 3–6 on each side, spaced at 5–13 mm, at 40–70° angle with the midvein, impressed on adaxial side, slightly raised on abaxial side; tertiary venation obscure on both sides. Inflorescences erect, capitate, tri-flowered, glabrous, sessile. Bracts axillary to each flower, 1 per flower, lanceolate to linear, 2–3 mm long, acute at apex, with straight margins, green, pilose on adaxial side. Flowers 5-merous, erect, style heterogeneity not seen; pedicels to 1 mm long, green; flower buds obovoid to spathulate, mature buds with corolla bent to one side. Hypanthium turbinate, 1.5–2 × 1.75 mm, smooth, green, glabrous; nectary disk entire, circular, to 0.6 mm in diameter, glabrous. Calyx chartaceous, green, glabrous outside, puberulous inside; tube to 0.75 mm long, colleters lacking; lobes triangular, 0.5 × 1 mm, obtuse at apex, erect, margins entire. Corolla actinomorphic, tubular, spongy, white, glabrous throughout; tube 22–23 mm long, throat narrow, 1.25 mm wide at base and 2.5–3 mm wide at mouth; lobes linear and curved, 11–12 × 1.2–2 mm, acute and hooked at apex, perpendicular to the tube (at anthesis), adaxial side verrucose, abaxial side smooth. Stamens partially exserted, glabrous; filaments linear, ca. 3 × 0.25 mm, terete, colour unknown, inserted ca. 4 mm below the corolla mouth; anthers ovoid, ca. 3.5 × 0.4 mm, pale yellow, dorsifixed. Style filiform, 16 × 0.25 mm, terete, colour unknown, glabrous. Stigma unknown. Fruits ovoid, 14–25 × 10–21 mm; exocarp smooth, white creamy, glabrous; mesocarp spongy and white. Pyrenes plano-convex, ovoid, 15–19 × 10–12 × 5–6 mm, acute and bifid at apex, round and emarginate at base; dorsal side convex, smooth, with 5 to 7 crests; ventral side flat, smooth; marginal pregermination slits two, short; exotesta reddish brown. Endosperm entire, not ruminate, gray, ethanol-soluble seed coat pigment lacking.

Distribution and habitat: — Psychotria ireneae Barrabé (this publication) is present in rainforests and at rainforest edges on volcano-sedimentary substrates. All the herbarium specimens seen were collected in these three areas, Aoupinié, Tchamba, and Görö Até, at 500–900 m elevation ( Fig. 3 ).

Phenology: —Specimens with flowers in bud and at anthesis were collected in January. Specimens with fruits were found in all months of the year.

Etymology: —This species is named for Irène Létocart, a naturalist who is passionate about the New Caledonian flora and who helped searching for plants during fieldwork.

Affinities: — Psychotria ireneae belongs to the ‘ trisulcata’ subclade (Barrabé 2013), which includes only one other species: P. trisulcata . Both these species are fastigiate shrubs with densely and regularly clustered leaves, 2–10 cm long. Also, in both species the stipules are reduced and truncate, the infloresences are subcapitate and tri-flowered, corollas are white, and the fruits are white to cream-white and up to 1 cm in diameter. Psychotria ireneae differs from P. trisulcata by its bright green, smooth leaves when fresh (vs. olive-green, whitish-variegate, and papillose), the midrib concolorous with the lamina (vs. black), its larger leaf blades 2.7–9.6 × 0.9–4.3 cm (vs. 1–6.5 × 0.5–1.9 cm), and fruits 14–25 × 10–21 mm (vs. 13–18 × 8–12 mm); the pyrenes are pyriform, 15–19 × 10–12 × 5–6 mm (vs. obovoid, 12.5–14 × 5–6 × 3.5–4 mm), with prominent crests on the dorsal side (vs. with smaller crests). These two species are found on volcano-sedimentary substrates of the north-eastern New Caledonia, in areas subject to high rainfall. However, their geographical distributions are different, as P. ireneae is recorded between Ponérihouen and Touho ( Fig. 3 ), and P. trisulcata from north of Touho.

Conservation assessment according to the IUCN Red List categories and criteria: —As Psychotria ireneae is known from only three localities: the Tchamba valley, Mount Görö Até, and the protected area of Mount Aoupinié; therefore, its extent of occurrence does not exceed 140 km ². Mount Aoupinié and the Tchamba valley are two of the largest areas of forest on the main island of New Caledonia that have been damaged in the past by logging, and this has most probably resulted in the decline of plant populations. Furthermore, the localities where P. ireneae has been found are near villages, where fires are widely used to prepare fields and to clear land before hunting ( Jaffré et al. 1998b). The edges of these forests are degraded year by year by human activities, and thus the area of forest habitat is progressively reduced ( Jaffré et al. 1998a). Additionally, large populations of introduced deer and pigs disturb the understory of these forests and the impact of these animals is considerable, as they destroy young plants, preventing the recruitment of new individuals into the population ( Beauvais et al. 2006). Even if P. ireneae occurs in forest that is only moderately affected, these factors will all have a negative impact on its population size, and consequently I assign this species a provisional threat status of Endangered: EN B1ab(i,ii,iii)+2ab(i,ii,iii).

Paratypes: — NEW CALEDONIA. Grande Terre, Province Nord: Aoupinié, 11 June 2002, V. Dumontet, Y. Blanchard & P. Maituku 155 (NOU-032648!); Aoupinié , 29 May 1997, M. Litaudon & P. Maituku 280 (NOU- 0032649!); Haute Tchamba , exploitation forestière Létocart , 500 m, 26 February 1970, H.S. MacKee (leg. J. Kusser) 21686 (K!); Ponérihouen , pente est du mont Aoupinié , exploitation forestière Devillers , 500 m, 26 March 1974, H.S. MacKee 28372 (K!, NOU-0032650!, P-00751986!); mont Görö Até , along trail from Alain Obry property, 890 m, 21°1’48’’S, 165°10’14’’E, 24 April 2002, G. McPherson & P.P. Lowry 18519 (MO!, NOU-0032652!); Tchamba, 600–700 m, 21°0’9’’S, 165°13’36’’E, 14 January 2004, A. Mouly, J. Munzinger, L. Vary, P.P. Lowry, T. Le Borgne & M. Schlessman 327 (BR, K, MO, P-00591930!); Ponérihouen, Tchamba, 500–600 m, 3 June 2007, A. Mouly, R. Amice, D. & I. Létocart, & Y. Pillon 781 (NOU-028069!, P-00592407!); Ponérihouen, Tchamba, 500–600 m, 3 June 2007, A. Mouly, R. Amice, D. & I. Létocart, & Y. Pillon 788 (NOU-028074!, P-00592407!); Haute Tchamba, 21°0’56’’S, 165°15’6’’E, 10 November 2002, J. Munzinger, F. Tronchet, D. & I. Létocart, & A. Oddi 1420 (MO, NOU-002663!, P- 00354567!, UPS); Tchamba, 21°18’S, 165°15’E, 15 July 2004, J. Munzinger 2237 (NOU-003532!); Aoupinié, parcelle 13 Goa, 554 m, 21°9’27’’S, 165°20’7’’E, 28 September 2010, J. Munzinger, V. Hequet & H. Vandrot 6069 (NOU- 053734!); Haute Tchamba, 18 July 1979, T. Sévennet & J. Pusset 1746 (NOU-0032653!); versant est de l’Aoupinié, 700 m, 27 September 1972, J.-M. Veillon 2744 (NOU-0032651!) .

Figures

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

FIGURE 4. Psychotria ireneae Barrabé. A. Branches with inflorescences and a young fruit; B. Detail of an inflorescence with a flower at anthesis; C. Stipule; D. Young fruit; E. Dorsal face of the pyrene; F. Ventral face of the pyrene; G. Cross section of the pyrene. Drawn by Michèle Magat.

FIGURE 5. Psychotria ireneae Barrabé. A. Habit; B. Flower at anthesis; C. Young fruit; D. Mature fruits. Photos by Laure Barrabé (A, B, C); Daniel & Irène Létocart (D).