Bidens woodii W.L. Wagner, J.R. Clark & Lorence, 2014

Wagner, Warren L., Clark, John R. & Lorence, David H., 2014, Revision of endemic Marquesas Islands Bidens (Asteraceae, Coreopsideae), PhytoKeys 38, pp. 37-67 : 50-51

5. Bidens woodii W.L. Wagner, J.R. Clark & Lorence sp. nov. Figure 6

Type.

Marquesas Islands. Ua Pou: Central Ua Pou including the summit crest regions around Oave and the nearby peak of Matahenua, 899-924 m, 9°23"S/140°4"W, 2 Jul 2004, Wood & Perlman 10806 (holotype: US-3547652; isotypes: BISH, P, PAP, PTBG) [used in molecular study, Funk et al.].

Description.

Erect, suffrutescent perennial herbs 0.5-1 m tall. Leaves simple, 5-7 cm long including petiole, petiole stout, blades thick and coriaceous, ovate to broadly ovate, 3-4.5 × 1.8-2.5 cm, glabrous, the veins on lower surface conspicuously raised, margins serrate, apex short-acuminate. Heads 1-2, in compact cymes terminating main stem and lateral branches, 4-5 mm in diameter excluding rays, peduncles ca. 2 cm long, stout, glabrous; outer involucral bracts ca. 3-4 mm long, broad, well differentiated from inner bracts; inner bracts dark purple, erose and with a few short hairs; ray florets ca. 6-8, sterile, rays yellow, obovate, 10-12 × 4-7 mm, apices often bi- or tri-lobed; disk florets ca. 30-34, perfect, corollas yellow; pappus absent. Achenes not seen.

Distribution.

Marquesas Islands, Ua Pou, known only from the type on the summit crest around Oave and the nearby peak of Matahenua, ca. 920 m.

Habitat.

Occurs in low shrubland of Metrosideros collina with Dicranopteris linearis on the windswept and cloud-shrouded summit area.

Etymology.

This new species is named for Kenneth R. Wood, who made the only known collection of it and who has contributed greatly to our knowledge of the flora of the Marquesas and Hawaii through his collections, excellent photography, and field observations.

Conservation status.

IUCN Red List Category Endangered (EN), criteria B2a, B2b i-iii: B2, total area of occupancy less than 500 km² (c. 50 km²); B2a, fragmented populations; b (i-iii), habitat continuing decline inferred. The suitable habitat for Bidens woodii on Ua Pou (c. 105 km²) is indicated as an endangered environment, threatened by human activity (deforestation, fire), feral animals, and invasive plants, thus reducing the extent of the suitable habitat.

Discussion.

Bidens woodii is most similar to Bidens evapelliana but can be differentiated by its habit (erect versus prostrate, and 0.5-1 m versus 0.3-0.5 m tall stem), leaves with raised venation, and obovate rays. It is known only from the type collection.

Figures

Figure 6. Bidens woodii W. L. Wagner, J. R. Clark & Lorence A Habit B Head showing involucral bracts, pales and achene tips C Pale D Ray corolla E Disk floret (without ovary) F Disk corolla longitudinal section G Achene. Drawn from Wood & Perlman 10806 (holotype, US).