Phymatodocis, 1878: 18
Holotype species: Phymatodocis alternans Nordstedt
Original publication and holotype designation:Nordstedt, C.F.O. (1878 '1877'). Nonnullae algae aquae dulcis brasilieses. Öfversigt af Kongl. Vetenskaps-Akademiens Forhandlingar 1877(3): 15-28, 2 pls.
Taxonomic status: currently recognized as a distinct genus.
Description: Cells united in short or long filaments. Cells quadrate to rectangular in lateral view, with moderately deep median constriction (isthmus). In apical view each semicell 4-lobed (rarely 3- or 5-lobed). Lobing symmetric except P. irregulare (two long and two short lobes). Cell wall of two pieces overlapping at isthmus. Open cylindrical pores typical of Cosmarium-type desmids, absent in P. nordstedtiana, the wall structure resembling Penium or Closterium, with dense matrix embedded among crossed bands of microfibrils. Funnel-shaped pores resemble those in Closterium, with narrow outer opening and broader inner region traversed by microfibrils. Chloroplast oneper semicell with one or two pyrenoids and two broad, flattened lobes extending into each lateral lobe of semicell. Nucleus in isthmus. Asexual reproduction by cell division and new semicell morphogenesis typical of desmids (see Cosmarium). P. nordstedtiana unique in that primary wall shed as small pieces very early, before full differentiation of new semicells (as opposed to after differentiation). Sexual reproduction observed in two species, by conjugation between cells that remain attached in filaments or dissociate. Gametes fuse within broad conjugation tube; mature zygospore irregularly quadrangular. Phymatodocis species all rare, usually in acidic, oligotrophic lakes in tropical or subtropical regions; one species extends to boreal forest of Canada. The taxonomic position of Phymatodocis uncertain. Wall ultrastructure suggests position intermediate between Cosmarium-type and Penium-type desmids. Further studies, including observations of type species needed to resolve this problem.
NCBI Nucleotide Sequences
Numbers of names and species: There are 17 species (and infraspecific) names in the database at present, of which 3 have been flagged as currently accepted taxonomically.
Names: ('C' indicates a name that is currently 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):
Phymatodocis alternans Nordstedt C - type
Phymatodocis irregulare Schmidle C
Phymatodocis irregulare f. sonfonense Woodhead & Tweed P
Phymatodocis irregulare var. profusum R.L.Grönblad & A.M.Scott P
Phymatodocis irregulare var. intermedium Gutwinski P
Phymatodocis irregulare var. intermedia Gutwinski C
Phymatodocis nordstedtiana f. minor Børgesen C
Phymatodocis nordstedtiana var. novizelandica Nordstedt C
Phymatodocis nordstedtiana var. nordstedtiana Wolle P
Phymatodocis nordstedtiana Wolle C
Phymatodocis nordstedtianum var. triangulare Prowse P
Phymatodocis nordstedtianum f. pentagonale Tell & Vélez P
Phymatodocis nordstedtianum var. novizelandicum Nordstedt P
Phymatodocis nordstedtianum f. minus Børgesen P
Phymatodocis nordstedtianum var. alternans (Nordstedt) Förster P
Phymatodocis nordstedtianum Wolle P
Phymatodocis simplex Förster & Eckert P
Hall, J.D., Karol, K.G., McCourt, R.M. & Delwiche, C.F. (2008). Phylogeny of the conjugating green algae based on chloroplast and mitochondrial nucleotide sequence data. Journal of Phycology 44: 467-477.
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.
Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=43540
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 09 December 2013.
Algaebase taxon LSID: urn:lsid:algaebase.org:taxname:6859