Holotype species: Pelagophycus giganteus Areschoug
Currently accepted name for the type species: Pelagophycus porra (Léman) Setchell
Original publication and holotype designation: Areschoug, J.E. (1881). Beskrifning på ett nytt algslägte Pelagophycus, hörande till Laminarieernas familj. Botaniska Notiser 1881: 49-50.
Taxonomic status: currently recognized as a distinct genus.
Most recent taxonomic treatment adopted: Silberfeld, T., Rousseau, F. & Reviers, B. de (2014). An updated classification of brown algae (Ochrophyta, Phaeophyceae). Cryptogamie Algologie 35(2): 117-156.
Arthrothamnus (Jackson et al., 2017). - (2 May 2017) - Wendy Guiry
Description: Thalli large, annual, but some plants may persist for 2 years. Holdfast flat and circular, composed of widely spreading, dichotomously branched, slender haptera, produced in irregular whorls. Single stipe, 3-27 m long, solid and terete throughout much of its length, the upper portion expanded into a hollow apophysis which is constricted near distal end and terminates in an oblong to spherical pneumatocyst, 6-20 cm in diameter. Short, thick stalk at top of pneumatocyst subtends a pair of sympodially branched "antler" systems, with a single blade borne at the end of each branch. Blades 5-20 m long, up to 1 m in width, thin, coarsely corrugated, with small spines along the margins and on both surfaces. Spores produced in unilocular sporangia with paraphyses in irregular extensive sori on both surfaces of the blades. Gametophytes dimorphic, dioecious, oogamous, branched uniseriate filaments. Pelagophycus occurs in extensive subtidal forests in the coastal waters of southern California and northwestern Baja California, Mexico, in waters of 20-90 m depth. The flattened holdfast typically anchors the plant in gravel or loose sediment bottoms. The pneumatocyst remains submerged. Three species have been proposed, all occurring in southern California. P. giganteus has a larger holdfast, a shorter stipe, a more elliptical pneumatocyst, more flattened "antlers" and larger but fewer blades than P. porra, with P. intermedius being intermediate in these characteristics. These species are considered ecotypes belonging to a single species. Natural hybrids of Pelagophycus and Macrocystis are known from nature and have also been produced in the laboratory. Natural hybrids have a lower longevity than Pelagophycus. These hybrids are sterile, although a recent hybrid was found to produce functional spores. Hybrids of Pelagophycus and Dictyoneuropsis were produced in the laboratory.
Information contributed by: R. J. Lewis. The most recent alteration to this page was made on 21 Jun 2014 by M.D. Guiry.
Numbers of names and species: There are 3 species names in the database at present, of which 1 has been flagged as accepted taxonomically on the basis of the listed literature under the species name. In some instances, opinions on taxonomic validity differ from author to author and users are encouraged to form their own opinion. AlgaeBase is a work in progress and should not be regarded as a definitive source only as a guide to the literature..
Names: ('C' indicates a name that is accepted taxonomically; 'S' a homotypic or heterotypic synonym; 'U' indicates a name of uncertain taxonomic status, but which has been subjected to some verification nomenclaturally; 'P' indicates a preliminary AlgaeBase entry that has not been subjected to any kind of verification. For more information on a species click on it to activate a link to the Species database):
Click here to also show infraspecific names in the list below.
Jackson, C., Salomaki, E.D., Lane, C.E. & Saunders, G.W. (2017). Kelp transcriptomes provide robust support for interfamilial relationships and revision of the little jnown Arthrothamnaceae (Laminariales) (Letter). Journal of Phycology 53(1): 1-6.
Verification of data
Users are responsible for verifying the accuracy of information before use, as noted on the website Content page.
Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in CD format. These AlgaeBase descriptions are now being continually updated, and each current contributor is identified above. The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and particularly the work of Dr Parker.
Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.
Created: 28 December 2000 by M.D. Guiry
Verified by: 21 June 2014 by M.D. Guiry
Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=42360
Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2019. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 20 April 2019.