title: Reproductive morphology and DNA sequences of the brown alga Platysiphon verticillatus support the new combination Platysiphon glacialis.
abstract: Platysiphon verticillatus, a brown alga endemic to the Arctic, was described based on vegetative specimens collected at Inglefield Bay, West Greenland. The species is distinctive in having a lanceolate blade-like thallus terminated by a terete portion, both covered with hair-like assimilatory filaments. Punctaria glacialis was described from Eastern Greenland, and the species differs from other Punctaria species in lacking hairs and plurilocular zoidangia. Unilocular zoidangia were reported, but instead of zoids being released they formed cell walls in situ developing the appearance of plurilocular zoidangia. However, the fate of the zoids, as well as the walled cells was not traced, and the life history of the alga has remained unclear. By comparing DNA sequences (cox1, cox3, and rDNA ITS2) of specimens morphologically referable to Platysiphon verticillatus and Punctaria glacialis collected at Baffin Island, as well as re-examining morphology and studying crude cultures, we concluded that they are the same taxonomic entity. Furthermore, their cox3 sequence and vegetative morphology agreed with those of the type specimen of Punctaria glacialis. Consequently, we propose Platysiphon glacialis comb. nov. The life cycle could not be completed in culture, but we hypothesize that in situ germination of the unizoids produces reduced gametophytes housed in peripheral tissue of erect sporophytic thalli.
authors.affiliation: Kobe University Research Center for Inland Seas, Rokkodai, Kobe, 657-8501, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawai
authors.affiliation: Kobe University Research Center for Inland Seas, Rokkodai, Kobe, 657-8501, Japan.
authors.forename: Takeaki
authors.initials: T
authors.lastname: Hanyuda
authors.affiliation: Kobe University Research Center for Inland Seas, Rokkodai, Kobe, 657-8501, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamagishi
authors.affiliation: Kobe University Research Center for Inland Seas, Rokkodai, Kobe, 657-8501, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kai
authors.affiliation: Department of Biological Sciences, University of Rhode Island, Kingston, Rhode Island, USA.
authors.forename: Chris E
authors.initials: CE
authors.lastname: Lane
authors.affiliation: Department of Biology, Edison State College, Fort Myers, Florida, USA.
authors.forename: Dan
authors.initials: D
authors.lastname: McDevit
authors.affiliation: Oceanlab, University of Aberdeen, Main Street, Newburgh, AB41 6AA, UK.
authors.forename: Frithjof C
authors.initials: FC
authors.lastname: Küpper
authors.affiliation: University of New Brunswick, Fredericton, New Brunswick, Canada.
authors.forename: Gary W
authors.initials: GW
authors.lastname: Saunders
keywords: Arctic Ocean; Phaeophyceae; Platysiphon glacialis comb. nov; life history; molecular phylogeny