Oparanthus woodii W. L. Wagner & Lorence, 2011

Wagner, Warren L. & Lorence, David H., 2011, Two new Marquesan species of the southeastern Polynesian genus Oparanthus (Asteraceae, Coreopsidinae), PhytoKeys 4, pp. 139-148 : 142-144

Oparanthus woodii W. L. Wagner & Lorence sp. nov. Fig. 2 3D

Latin.

Ab O. teikiteetinii fere glabra arbore, domatiis apilosis in foliis abaxialibus in axilibus nervis secundariis presentibus, foliis basi connatis, flosculis radiorum tubis corollarum 7.5-8 mm differt.

Type.

Marquesas Islands: Nuku Hiva: Ooumu region, top of Tapueahu Valley off new Hwy, [08 51'53S, 140 10'63W], 1067-1128 m, 23 June 1997, K. R. Wood 6375 (Holotype: PTBG-025565!; isotypes: BISH!, P!, PAP!, US!).

Description.

Trees 2-5 m tall, glabrous, functionally monoecious, moderately to diffusely branched, the trunk often with multiple prop roots, bark brown, wood cream-colored. Leaves thinly coriaceous, the blade broadly elliptic to broadly elliptic-obovate, 11-23.1 × 3.5-12.7 cm, secondary veins 4-12 mm apart, conspicuously arching upward from midrib, then spreading to margin, abaxial axils often with domatia, these without associated hairs, margins entire, apex rounded to truncate, base cuneate, often oblique; petioles 3.5-6 cm long, the base conspicuously connate around stem with paired leaf petiole. Inflorescences terminal, heads solitary, 12-16 mm in diameter, 22-35 mm high, peduncles 3-15 mm long, stout; involucre campanulate; involucral bracts 8, in 2 series, the external ones 8-13 mm long, connate at the base, thick and broadly triangular, becoming lignified in fruit, the internal ones usually longer (up to 15 mm) and narrower, triangular to elliptic; receptacular bracts of the ray florets 13-14 mm long, those of the disk florets 12-13 mm long; ray florets ca. 18-22, in 2 series, corolla tube and throat 7.5-8 mm long, limb 4.2-4.5 mm long, 2-3-lobed, the lobes usually divided to near corolla throat, occasionally only shallowly so; disk florets ca. 40-50 or perhaps more, corolla tube and throat 6.3-6.6 mm long, the lobes 4.4-5.4 mm long. Ray achenes elliptic, 5-6 mm long, distinctly winged, the wings ca.1 mm wide, extending slightly beyond the achene apex; disk achenes sterile, linear, 10-11 mm long, with 2 awns.

Etymology.

This new species is named for Kenneth R. Wood, who first collected it and who has contributed greatly to our knowledge of the flora of the Marquesas and Hawaii through his collections and field observations.

Distribution.

Endemic to Nuku Hiva, Marquesas Islands, and apparently restricted to the Ooumu region, in gulches near the top of Tapueahu Valley, from 1060 to 1130 m elevation.

Ecology.

Occurring in montane mesic to wet forest, ravines and steep slopes, with Metrosideros and Weinmannia dominant and a diverse understory of Asplenium , Blechmum , Cyrtandra , Hypolepis , Ilex , and Melicope , with stands of Freycinetia nearby. Known to flower in June, but probably for some months after that.

Conservation status.

Based on the IUCN criteria and categories this species is assigned a preliminary Red List status of Critically Endangered (CR) B2a, B2b (i-iii); D: B2: total area of occupancy less than 10 km2 (ca. 5 km2). B2a, a single population known; b ( i–iii), habitat continuing decline inferred; D, population estimated to number fewer than 250 individuals. The suitable habitat for Oparanthus woodii on Nuku Hiva (c. 340 km2) is indicated as an endangered environment, threatened by human activity (deforestation and fire), feral animals, and invasive plants, thus reducing the extent of the forest.

Discussion.

Oparanthus woodii appears to be closely related to Oparanthus teikiteetinii , which grows at lower elevations, but approaches the known range of Oparanthus woodii within a few hundred meters. While Oparanthus teikiteetinii is generally distinctive in the genus for its large size, attaining heights of up to 12 m, and for its large, often solitary capitula, Oparanthus woodii is a smaller tree up to 5 m tall and has large solitary heads on much shorter and stouter peduncles up to 15 mm long. The corollas are similar in these two species, but the ray corollas of Oparanthus woodii are also distinctive in that they are deeply divided to near the corolla throat. Likewise the leaves of Oparanthus woodii are distinctive in that they are conspicuously connate at the petiole bases, have secondary veins that arch upwards, and havenaked domatia in the abaxial vein axils. These are not always present and they lack the tufts of hairs in the always present domatia of Oparanthus hivoanus and Oparanthus tiva .

Specimens examined.

Marquesas Islands: MARQUESAS ISLANDS: Nuku Hiva, Ooumu region, top of Tapueahu Valley off new Hwy, [08 51'53S, 140 10'63W], Wood et. al. 6338 (P, PTBG, US); Wood 6376 (PTBG, US); Wood 6377 (BISH, K, P, PAP, PTBG, US).