New taxa and new combinations in Hawaiian Bidens (Asteraceae)

Abstract

In the course of our investigation of the genetics of adaptive radiation and evolution of Bidens in the Hawaiian Islands, it has been necessary to revise the group taxonomically. Here we describe four new subspecies and make three new combinations at the rank of subspecies. Bidens sandvicensis ssp. confusa Nagata & Ganders, B. hillebrandiana ssp. polycephala Nagata & Ganders, B. micrantha ssp. kalealaha Nagata & Ganders, and B. forbesii ssp. kahiliensis Ganders & Nagata are described as new. Bidens campylotheca ssp. pentamera (Sherff) Ganders & Nagata, B. menziesii ssp. filijormis (Sherff) Ganders & Nagata, and B. micrantha ssp. ctenophylla (Sherff) Nagata & Ganders are published as new combinations at subspecific rank. A key to all taxa of Bidens in the Hawaiian Islands is provided. It includes introduced taxa that have been collected in the islands in the last 80 years.