title: PHENOTYPIC PLASTICITY RECONCILES INCONGRUOUS MOLECULAR AND MORPHOLOGICAL TAXONOMIES: THE GIANT KELP, MACROCYSTIS (LAMINARIALES, PHAEOPHYCEAE), IS A MONOSPECIFIC GENUS(1).
abstract: The giant kelp genus Macrocystis C. Agardh (Laminariales, Phaeophyceae) is one of the world's most ecologically and economically important seaweed taxa, yet its taxonomy remains uncertain. Although the genus currently contains four accepted species based on variable holdfast and blade morphology [M. pyrifera (L.) C. Agardh, M. integrifolia Bory, M. angustifolia Bory, and M. laevis C. H. Hay], numerous recent studies on Macrocystis interfertility, genetic relatedness, and morphological plasticity all suggest that the genus is monospecific. We reviewed this evidence and present an explanation for the extreme phenotypic plasticity that results in morphological variability within Macrocystis, driven by the effects of environmental factors on early development of macroscopic sporophytes. We propose that the genus be collapsed back to a single species, with nomenclatural priority given to M. pyrifera.
authors.affiliation: Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California 95039, USA.
authors.forename: Kyle W
authors.initials: KW
authors.lastname: Demes
authors.affiliation: Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California 95039, USA.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Graham
authors.affiliation: Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California 95039, USA.
authors.forename: Thew S
authors.initials: TS
authors.lastname: Suskiewicz
keywords: Macrocystis; interfertility; morphology; phenotypic plasticity; synonymy