Bidens evapelliana 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 : 51-52

6. Bidens evapelliana W.L. Wagner, J.R. Clark & Lorence sp. nov. Figures 7 , 8

Type.

Marquesas Islands. Fatu Hiva: Slopes of Mounanui, on open ridge, 10°28'656"S/138°38'149"W, 730 m, 16 Jul 2005, Perlman 19665 (holotype: PTBG-066395; isotypes: BISH, MO, P, US).

Description.

Prostrate, suffrutescent perennial herbs up to 0.3-0.5 m tall. Leaves simple, coriaceous, 1.3-3.6(-7) cm long including petiole, petiole relatively short, blades elliptic to ovate, 1-2.8(-5.6) × 0.7-2(-3.5) cm, glabrous, margins serrate, apex rounded to acute. Heads 1-3, in compact cymes terminating main stem and lateral branches, 4-8 mm in diameter excluding rays, peduncles 1-2.5 cm long, glabrous; outer involucral bracts 4-6 mm long, broad, well differentiated from inner bracts; ray florets normally 3-6 per head, sterile, rays yellow, ca. 8 × 2-5 mm; disk florets ca. 23-25, perfect. Achenes tawny to gray, straight, ca. 5 × 1 mm, slightly keeled, glabrous; pappus of 2 irregular antrorse barbed awns.

Disribution.

Marquesas Islands, known only from the south-central part of Fatu Hiva from Mt. Natahu and Teavapuhiau Pass to Mounanui and Touaouoho, 700-850 m.

Habitat.

Scattered on ridgetops and cliffs, in scrubland or low forest of Metrosideros collina , Freycinetia impavida , Crossostylis biflora J.R. Forst. & G. Forst., Hibiscus tiliaceus , Pandanus sp., Weinmannia marquesana , and Dicranopteris linearis .

Etymology.

This species is named in honor of Eva Pell, Under Secretary for Science at the Smithsonian Institution upon her retirement. She served in this position from 2010 to 2014 during which time she worked to strengthen science across the institution. Her accomplishments include creation of the four "Grand Challenges Consortia," which have been instrumental in developing interdisciplinary collaborations across the Smithsonian. She also played a key role in creating the Smithsonian’s Tennenbaum Marine Observatories Network, the first worldwide network of coastal field sites to standardize measurements of biological change in marine environments.

Conservation status.

Proposed IUCN Red List Category: Critically Endangered (CR), criteria B1ab, B2a,b (i-iii): B1, total extent of occurrence less than 100 km² (less than 10 km²); a,b, known from a single location; B2a, area of occupancy estimated to be less than 10 km²; B2b (i-iii), habitat continuing decline inferred. The estimated area of occupancy for Bidens evapelliana on Fatu Hiva (ca. 85 km²) is indicated as an endangered environment, threatened by human activity (deforestation and fire), feral animals (goats), and invasive plant species, thus reducing the extent of the forest.

Specimens examined.

Marquesas Islands. Fatu Hiva: Along base of Mt. Natahu, 828 m, 1-3 Aug 1977, Gagné 1266 (BISH); Teavapuhiau Pass, above Ouia Valley, W of pass, 700 m, 1-3 Aug 1977, Gagné 1252 (BISH); Mt. Touaouoho, on NW side of peak, along ridges between Touaouho and Teavapuhiau, 2650 ft [808 m], 8 Sep 1995, Perlman & Wood 14959 (PTBG, US); Crete Ouest du Mt. Mounanui, 810 m, 10°28"S/138°37"W, 26 Jul 1988, Florence & Perlman 9590 (BISH, P, PTBG, US); slopes of Mounanui above Vaieenui Falls, on ridge top, below Mounanui, 2500 ft [760 m], 26 Jul 1988, Perlman & Florence 10166 (AD, BISH, F, MO, NY, OS, P, PAP, PTBG, TEX, UBC, US); on ridges west side of Mounanui, on ridge leading up from Cascade, 2400 ft [732 m], 10 Sep 1995, Perlman 14977 (BISH, P, PAP, PTBG, US); slopes of Mounanui above Vaieenui Falls, on ridge top, below Maunanui, 2780 ft [847 m], 26 Jul 1988, Perlman & Florence 10173 (BISH).

Discussion.

Bidens evapelliana is distinctive in its nearly exclusive prostrate habit and relatively small elliptic to ovate leaves. One specimen, Perlman 14959, is somewhat atypical to other collections of Bidens evapelliana in that it has larger leaf blades 4.3-5.6 × 2.0-3.5 cm, petioles up to 2 cm long, and slightly longer involucral bracts (ca. 6 mm).

Figures

Figure 7. Bidens evapelliana W. L. Wagner, J. R. Clark & Lorence A Habit B Young head showing pre-flowering florets C Head showing ray and disk florets D Ray corolla E Disk corolla F Achene. Drawn from Perlman 19665 (isotype, US) and field images of collection [A, B], and Florence & Perlman 9590 (US) [C-F].

Figure 8. Bidens evapelliana W. L. Wagner, J. R. Clark & Lorence A Habit B Head post-flowering showing involucral bracts and apex of achenes C Young head showing immature rays and involucral bracts D Disk corolla E Disk corolla longitudinal section F Achene G Inset showing achene surface. Drawn from Perlman 10166 (PTBG) [A], Perlman 19665 (isotype, US) [B], and Florence & Perlman 9590 (US) [C-G].