Holotype species: Sphaerotrichia divaricata (C.Agardh) Kylin
Original publication and holotype designation: Kylin, H. (1940). Die Phaeophyceenordnung Chordariales. Acta Universitatis Lundensis 36(9): 1-67, 30 figs.
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.
Description: Plants epilithic or epiphytic, attached by small disc, solitary or caespitose, terete, solid later becoming hollow, slightly gelatinous, irregularly dichotomously or alternately branched several times, gradually attenuated towards apex, yellowish to dark brown in color, haplostichous, composed of several layers of colorless, large, elongated medullary filaments, pigmented roundish cortical cells and 3-5 celled assimilatory filaments. Each cell contains several chloroplasts with pyrenoids. Rhizoidal filaments often present in the central hollow area. Terminal cells of assimilatory filaments obviously swollen and larger than the cells below them. Unilocular sporangia formed on entire thallus, on basal cells of assimilatory filaments, ovate, pyriform, up to 140 µm in length and 25 µm in diameter. Phaeophycean hairs scattered and abundant. Plurilocular sporangia not detected on erect thalli.
Information contributed by: H. Kawai. The most recent alteration to this page was made on 20 Jun 2014 by M.D. Guiry.
Comments: Mainly distributed in temperate area of Pacific and Atlantic Ocean. Recently introduced to Mediterranean coast. In recent culture studies, Ajisaka and Umezaki (1978) cultured Japanese S. divaricata and reported typical heteromorphic life history with sexual reproduction. Unispores developed into bushy filamentous gametophytes forming uniseriate plurilocular sporangia. Those plurispores copulated and the zygote developed into erect thalli forming unilocular sporangia. Unfused gametes reproduced gametophytes. Chromosome counts in diploid sporophyte 2n = 18-24. Peters and others (1987) cultured several strains of S. divaricata from North Pacific and North Atlantic and showed sexual heteromorphic life history between dioecious filamentous gametophytes and erect thalli, or asexual direct type of reproduction according to the strains. They reported the chromosome number of S. divaricata as n = 14-18.
Numbers of names and species: There are 7 species names in the database at present, as well as 4 infraspecific names. Of the species names, 5 have 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.
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: 20 June 2014 by M.D. Guiry
Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=32918
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 24 June 2019.