Bidens meyeri V.A. Funk & K.R. Wood, 2014

Funk, Vicki A. & Wood, Kenneth R., 2014, Bidens meyeri (Asteraceae, Coreopsideae): a new critically endangered species from Rapa, Austral Islands, PhytoKeys 42, pp. 39-47 : 41-42

Bidens meyeri V.A. Funk & K.R. Wood sp. nov. Fig. 2A-C

Type.

Austral Islands. Rapa, cliffs above Maitua, rappel below Maungaoa, 3 Apr 2002, K.R. Wood & Heimoana Faraire 9515 (holotype: PTBG-067702!); 27°37'30"S; 144°20'20"W.

Description.

Sub-shrub with 3-4 branches growing on cliff faces, ca. 25 cm tall, small side branches ca. 8 cm tall; stems brown, glabrous, lower portion smooth, upper portion striated, ca. 1 mm wide (when dry), glabrous, older nodes with the remains of leaf bases. Leaves opposite, simple, somewhat fleshy, glabrous, without true petioles but looking petiolate because of narrowed blade bases, 2.1-2.3 cm long; broad part of leaf ovate, glossy green above, dull green below, 1.1-1.5 cm long × 1.0-1.2 cm wide; margins of broad part of leaf dentate with teeth curved toward apex and with mucronate tips, 6-9 teeth per side; apex mucronate or apiculate; venation pinnate usually with one lateral vein for each tooth; narrow portion of leaf ca. 1 cm long decurrent with leaf bases wrapping around stem and nearly touching one another. Heads solitary, ~ 1 cm in diameter (excluding rays), peduncle 3 cm long, glabrous with prominent ribs (when dried); involucral bracts in 2-3 rows, outer two rows bright green, purple tipped in some, slightly fleshy, glabrous with 3 prominent veins (when dried), arched outward, ca. 5 mm × 1.3 mm (at the broadest point near the apex), apex rounded with a small acute tip; innermost row (may also be outer row of receptacular bracts) lanceolate, brownish with lighter hyaline margins, glabrous, 5.5 mm × 1.1 mm (at widest point near the base). Ray flowers yellow with many veins, 8-9 per head, sterile, ca. 9 mm long (including 2 mm tube) × 1.5-2.0 mm wide; disk flowers ca. 30-40, perfect; corollas yellow, glabrous; anther thecae dark, pollen yellow; style branches yellow. Pappus of 2 very short irregular awns with scattered hairs but without barbs. Achenes immature but apparently dark colored and glabrous, at least near the apex.

Additional collection.

Austral Islands: Rapa, Tevaitau on cliff, only two plants seen, 272 m, on bare rock, 16 Dec 2002, J.-Y. Meyer 2315 (Specimen hopefully at P). Fig. 1.

Distribution and ecology.

The type of Bidens meyeri was discovered during a rappel utilizing ropes and climbing-saddle around the windswept mesic cliffs above Maitua, Rapa, French Polynesia. The holotype location is the only population of any size; the second collecting site had only two individuals. The type locality can be described as a windswept mesic cliff habitat with small ledges and pockets of granular soil, bordered by steep slopes interspersed with herbs and low-statured native forest and shrubland. The aspect is northeast with a 70% open canopy for exposure to sun. Associated tree species include Oparanthus coriaceus (F. Br.) Sherff, Oparanthus rapensis (F. Br.) Sherff, Corokia collenettei Riley, Fitchia rapense F. Br., Metrosideros collina (J. R. Forst. & G. Forst.) A. Gray var. villosa (L.) A. Gray, Apetahia margaretae (F. Br.) Wimmer, and Sophora rapaensis H. St. John. Shrubs, vines, and herbs include Plantago rupicola Pilg., Dianella intermedia Endl. var. punctata F. Br., Veronica rapensis F. Br., Kadua rapensis F. Br., Alyxia stellata (J.R. Forst. & G. Forst.) Roem. & Schult., Dichelachne crinita (L. f.) Hook. f., and some Freycinetia arborea Gaudich. Associated ferns include Blechnum attenuatum (Sw.) Mett., Blechnum vulcanicum (Blume) Kuhn var. rapense E.D. Br., Sphaeropteris medullaris (G. Forst.) Bernh., Alsophila stokesii (E.D. Br.) R.M. Tryon, Polystichum rapense E.D. Br., Belvisia dura (Copel.) Copel., Thelypteris margaretae (E.D. Br.) Ching, Davallia solida (G. Forst.) Sw., Selaginella arbuscula (Kaulf.) Spring, Nephrolepis exaltata (L.) Schott, and Pteris comans G. Forst ( Wood 2002, pers. com.). Meyer 2315 was collected at a site with Pyrrosia serpens (G. Forst.) Ching, Peperomia sp., Verbena litoralis Kunth, Commelina diffusa Burm. f, Davallia solida (G. Forst.) Sw. and Psilotum nudum (L.) P. Beauv (pers. com.).

Etymology.

The new species is named in honor of Dr. Jean-Yves Meyer, friend and conservation biologist at the Délégation à la Recherche, Polynésie Française, in recognition of his research of this species and his efforts in exploring and conserving the unique biota of Rapa (e.g., Meyer 2011).