Ochrosia brownii (Fosberg & Sachet) Lorence & Butaud, 2011

Lorence, David H. & Butaud, Jean-Francois, 2011, A reassessment of Marquesan Ochrosia and Rauvolfia (Apocynaceae) with two new combinations, PhytoKeys 4, pp. 95-107 : 97-99

Ochrosia brownii (Fosberg & Sachet) Lorence & Butaud comb. nov. Figs 1A, B

Neisosperma brownii Fosberg & Sachet, Micronesica 8: 49, 1972 [as Neiosperma ]). [Basionym]

Type.

Marquesas Islands: Nuku Hiva: without precise locality, 15 July 1921, F. B. H. Brown 541 (Holotype BISH-500905!).

Ochrosia parviflora sensu F. Br., non (G. Forst.) Henslow

Description.

Tree to 13 m tall, trunk to 24 cm diam., branchlets glabrous, leafy twigs 4-4.5 mm in diam, terete, drying wrinkled, older leafless twigs 6-7 mm in diam., latex white. Leaves opposite on smaller branchlets, ternate on larger branchlets, petiolate, leaf axils with dark brown, linear-digitate colleters 1-1.5 mm long secreting pale yellow resin; blades obovate-elliptic, 9.4-16.5 × 3.2-6.4 cm, base narrowly cuneate, attenuate, apex shortly acuminate, glabrous, discolorous, drying brown above, yellowish-brown below, when fresh green to yellow green above, pale green below, both surfaces glossy, secondary veins 15-20 on each side, secondary and tertiary veins visible above, prominulous beneath, margins conspicuously and tightly revolute; petioles 17 -33 mm long, 1.7-2 mm in diam. Inflorescence terminal, 7-12 cm long, trichotomous, branching to the third degree, with 2 primary branches at apex of peduncle, each with 12-18 flowers, glabrous, axes with small, scale-like bracts; flowers on pedicels 1.5-4 mm long, 5-merous; calyx lobes obtuse to rounded, 2 × 2.5 mm; corolla in bud to 10 mm long; corolla at anthesis white, fragrant, corolla tube 6-7 × 3 mm, corolla lobes 5, contorted to the right, 6-7 × 2-25 mm, rounded at apex; ovary conical, 0.7-0.8 mm long, bicarpellate, style 0.8 mm long, stigmatic head ovoid, 0.7-0.8 mm long with tuft of hairs at apex and green ring (but no collar) at base, nectary 0.3 mm, 2-lobed, the lobes alternating with and partly covering the carpels. Infructescence with peduncle c. 17 cm long; fruits composed of two fleshy mericarps, when fresh orange at maturity, ellipsoid, 37-53 × 27-37 × 25-36 mm, mesocarp orange, 5 mm thick; endocarp externally fibrous, internally woody, 31-48 × 23-33 × 19-27 mm, the fibers to 1.5 mm in diam. Seed 2 per fruit, ellipsoid, 25 × 23-26 × c. 4 mm.

Distribution.

Nuku Hiva, Marquesas Islands, originally known only from the type collected in the vicinity of the Toovii plateau at about 900 m ( Brown 1935). The species was rediscovered by Jean-François Butaud in 2003 on Nuku Hiva where a single tree and some juveniles were located on the Vaioa plateau (at Matahamo, also called Vaipupui) SE of Toovii.

Ecology.

This species occurs in evergreen wet forest between 730 and 900 m elevation, with species of Hibiscus , Ixora , Metrosideros , Pandanus , Phyllanthus , Premna , Wikstroemia , Xylosma , and ferns including Asplenium australasicum (J. Sm.) Hook., Histiopteris incisa (Thunb.) J. Sm., and Microsorum grossum (Langsd. & Fisch.) Brownlie.

Conservation status.

When evaluated using the IUCN criteria for endangerment (IUCN 2001) Ochrosia brownii falls into the Critically Endangered (CR) category, which designates species facing the highest risk of extinction in the wild. IUCN Red List Category: Critically Endangered (CR) B1a, b; B2a, B2b ( i–iii): B1, extent of occurrence estimated to be less than 100 km2, and B1a, known to exist at only a single location; B1b (i-iii), continuing projected decline in (i) extent of occurrence, (ii) area of occupancy, and (iii) area, extent and quality of habitat; B2, area of occupancy estimated to be less than 10 km2, and B2a, a single population known. B2b ( i–iii), habitat continuing decline inferred. The suitable habitat for Ochrosia brownii on Nuku Hiva (c. 340 km2) is indicated as an endangered environment, threatened by human activity (deforestation and fire), feral animals, and invasive plants, reducing the extent of the forest.

Specimens examined.

Marquesas Islands: Nuku Hiva: Matahamo, Vaioa, fin de la piste forestière, 758 m, 2 Jan. 2003, Butaud 8 (PAP); Matahamo, Vaioa, 758 m, 9 Feb. 2003, Butaud 10 (PAP); Vaipupui, amont de la piste forestière menant à la dernière parcelle de pins, 737 m, 27 Jan. 2010, Butaud & Benne 2586 (PAP).

Discusison.

Since 2006, a conservation plan proposed by the Environment Direction of French Polynesia has been implemented, with conservation ex situ (seed collection and conservatory plantings) and in situ (fencing enclosure of the population and enrichment planting of seedlings inside).