SUBPHYLUM RHODELLOPHYTINA

Unicellular or pseudofilamentous. No sexual reproduction.

• CLASS RHODELLOPHYCEAE
  • Single class with characters of the subphylum.
  • ORDER RHODELLIALES (Called Porphyridiales 1 in Saunders and Hommersand 2004).
    • Golgi associated with ER and nucleus
    • Rhodella, Dixoniella, Glaucosphaera
  • ORDER STYLONEMATALES (Called Porphyridiales 2 in Saunders and Hommersand 2004).
    • Golgi associated with ER and mitochondria
    • Stylonema, Bangiopsis, Chroodactylon, Chroothece, Goniotrichopsis, Rhodosorus
  • ORDER PORPHYRIDIALES (Called Porphyridiales 3 in Saunders and Hommersand 2004).
    • Unicellular; Golgi associated with ER and mitochondria; no encircling thyllakoids.
    • Porphyridium, Flintiella

SUBPHYLUM METARHODOPHYTINA

Monosporangia and spermatangia simple and derived from vegetative cells. Life history biphasic.

• CLASS COMSPOPOGONOPHYCEAE
  • pseudoparenchymatous bases
  • ORDER COMPSOPOGONALES
    • Diffuse (not apical) growth; pit connections.
    • Compsopogon, Compsopogonopsis, Boldia
    • BOLDIACEAE; COMPSOPOGONACEAE
  • ORDER ERTHROPELTIDALES
    • ERYTHROTRICHIACEAE Erythrotrichopeltis, Smithora, Erythrotrichia, Erythrocladia, Erythropeltis, Erythrotrichia, Porphyropsis.
  • ORDER RHODOCHAETALES
    • Filamentous with apical growth, life history slightly heteromorphic; pit connections.
    • RHODOCHAETACEAE Rhodochaete

SUBPHYLUM EURHOPHYTINA

Golgi associated with endoplasmic reticulum and mitochondria. Life histories are biphasic and triphasic. Pit plugs are present in at least one stage of the life history.

• CLASS BANGIOPHYCEAE
  • Life history is biphasic with heteromorphic alternation of generation. Gametophyte uniseriate becoming pleuriseriate (or foliose). Sporophyte filamentous with pit plugs; forms conchospores.
  • ORDER BANGIALES
    • Alternation of generations between a thalloid and filamentous (conchocelis) stage which often inhabits old mollusk shells; many types of spores formed; sexual reproduction probably occurs.
    • Bangia, Porphyra, Porphyrella

• CLASS FLORIDEOPHYCEAE
  • Filamentous or pseudoparenchymatous; sexual reproduction by spermatia and very complex carpogonium leading to formation of carpospores; in most, an alternate sporophyte generation produces tetraspores; gametophyte stage haploid, carposporophyte stage either haploid or diploid; connections occur between cells. Taxonomy based on details of the complex sexual reproductive apparatus.
  • SUBCLASS HILDENBRANDIOPHYCIDAE
    • Variable; crustose to upright filaments made of lateral basal filaments and branched erect filaments; sexual reproduction unknown. Pit plugs with single cap layer and membrane.
    • ORDER HILDENBRANDIALES
      • Hildenbrandia
  • SUBCLASS NEMALIOPHYCIDAE
    • Pit plugs with 2 cap layers.
    • ORDER NEMALIALES
      • Multiaxial filamentous construction forming gelatinous algae. No auxiliary cell.
      • Nemalion, Liagora, Pseudogloiophloea, Galaxaura, Kylinia, Cumagloia.
    • ORDER ACROCHAETIALES
      • Simple branched uniseriate filaments; pit plugs with cap membranes; carposporangia in vegetative cells; isomorphic and biphasic; marine and freshwater (Harper and Saunders 2002).
      • Acrochaetium, Audouinella, Rhodochorton, Yamadaella.
    • ORDER BALBIANIALES
      • Identified as an order by Saunders and Hommersand (2004) by molecular means.
      • Balbiana.
    • ORDER BALLIALES
      • Identified as an order by Saunders and Hommersand (2004) by molecular means.
      • Ballia.
    • ORDER BATRACHOSPERMALES
      • Meiosis occurs without the formation of tetraspores, undifferentiated vegetative cells undergo meiosis which continue to grow; exclusively found in fresh water; heterotrichous; many discoid chloroplasts without pyrenoids.
      • Batrachospermum, Lemanea, Sirodotia.
    • ORDER COLACONEMATALES
      • Monosiphonous, simple or branched filaments, chloroplasts 1-several per cell, with or without pyrenoids, monospores, triphasic life history (Harper and Saunders 2002).
      • Colaconema.
    • ORDER CORALLINALES
      • Meristems apical and intercalary; conceptacles; cell walls with calcite; 2-celled carpogonial branch on a supporting cell which serves as an auxiliary cell.
      • Corallina, Bossiella, Calliathron, Choreonema, Jania, Lithoporella, Lithothamnium, Lithothrix, Phymatolithon, Porolithon, Sporolithon, Kvaleya, Amphiroa, Melobesia, Clathromorphum.
    • ORDER PALMERIALES
      • Unusual tetraspore production in which repeated production can occur within the same thallus; life history unusual, tetrasporophyte resembles the spermatangial gametophyte but the female gametophyte is very small.
      • Palmaria, Halosaccion, Rhodophysema. Camontagnea.
    • ORDER RHODOGORGONALES
      • Calciferous cells; no defined meristem, no secondary pit connections, dioecious, no auxillary cells; carposporangium from diffuse gonimoblast filaments; marine (Fredericq and Norris 1995).
      • Rhodogorgon, Renouxia.
    • ORDER THOREALES
      • Multiaxial gametophytic filaments alternating with uniaxial sporophyte; pit plugs with plate-like outer caps; Freshwater (Muller et al. 2002).
      • Thorea.
  • SUBCLASS AHNFELDTOPHYCIDAE
    • Carpogonia terminal and sessile; carposporangia develop outwards; pit plugs naked without caps or membranes.
    • ORDER AHNFELTIALES
      • With carposporangia.
      • Ahnfeltia, Gymnogongrus, Phyllophora, Stenogramme.
    • ORDER PIHIELLALES
      • Reproduction by monospores; no carposporophyte or tetrasporangia; no secondary pit connections; epi/endophytic plants of minute discoid pseudoparenchymatous thalli; marine (Huisman et al. 2003).
      • Pihiella.
  • SUBCLASS RHODYMENIOPHYCIDAE
    • Life histories triphasic; carposporophyte grows directly from carposporangium or from auxiliary cell. Pit plugs with membranes.
    • ORDER RHODYMENIALES
      • Multiaxial thalli with the formation of a carpogonial procarp. Auxillary cell at the end of a 2-celled filament which branches from the supporting cell. Carpogonial procarp made of 3 or 4-celled carpogonial branches and the auxillary cell.
      • Rhodymenia, Botryocladia, Chrysymenia, Coelarthrum, Coelothrix, Fauchia, Halosaccion, Champia, Chylocladia, Coeloseira, Gasstroclonium, Lomentaria.
    • ORDER BONNEMAISONIALES
      • Triphasic heteromorphic life histories and bipolar spore germination (like Ceramiales).
      • Asparagopsis, Bonnemaisonia, Delisia, Ptilonia.
    • ORDER CERAMIALES
      • Mostly branched, filamentous; some form delicate thalli by pseudoparenchymatous aggregation and by growth of corticating filaments. Auxiliary cell formed after fertilization from a supporting cell; carpogonial branches always 4-celled.
      • Ceramium, Aristothamnion, Bornetia, Compsothamnion, Corynospora, Crouania, Dohrniella, Ptilota, Griffithsia, Pleonosporium, Plumaria, Ptilothamniopsis, Seirospora, Spermothamnion, Tiffaniella, Callithamnion, Antithamnion, Bostrychia, Chondria, Colacopsis, Lenormandia, Heterosiphonia, Dasya, Platysiphonia, Membranoptera, Delesseria, Caloglossa, Phycodrys, Polyneura, Polysiphonia, Petrosiphonia, Amplisiphonia, Rhodomela, Rytiphlaea, Vidalia, Laurencia, Cryptopleura, Hemineura, Hypoglossum, Martensia, Nitophyllum, Rhodoptilum.
    • ORDER GELIDIALES
      • Uniaxial thalli, dome-shaped apical cell; prostrate filaments from which arise several erect filaments; unique spore germination pattern (germ tube emerges from germinating tetraspore and cytoplasm flows into the tube), and 1-layered pit plug caps (Graham and Wilcox 2000).
      • Gelidium, Pterocladia, Suhria.
    • ORDER GIGARTINALES
      • Small, with multiaxial pseudoparenchymatous construction and rather cartilaginous texture. Auxiliary cell borne on intercalary cell of ordinary cell of vegetative filament.
      • Gigartina, Acrosymphyton, Dumontia, Mastocarpus, Chondrus, Iridaea, Phyllophora, Gymnogongrus, Cruoria, Cruoriopsis, Pterocoelis, Bertholdia, Furcellaria, Halarachnion, Neurocaulon, Rhodophyllis, Cystoclonium, Calliblepharis, Polyides, Besa, Neoardhiella, Opuntiella, Euchemia, Gracilaria, Gracilariophila.
    • ORDER GRACILARIALES
      • These fleshy plants are pseudoparenchymatous and are economically important in that they provide more than half of the world’s agar. “Female” cell with a supporting cell of intercalary origin with a 2-celled carpogonial branch; marine (Fredericq and Hommersand 1989).
      • Gracilaria, Gracilariopsis, Gracilariophila, Hydropuntia.
    • ORDER HALYMENIALES
      • Multiaxial species; triphasic life histories with isomorphic alternation of gametophyte and tetrasporophyte generations; carpogonia 2-4 celled, often connecting to intercalary auxillary cells making them diploids (Saunders et al. 2004).
      • Cryptonemia, Grateloupia, Halymenia, Lobocolax, Pachymeniopsis, Prionitis, Sebdenia.
    • ORDER NEMASTOMATALES
      • Multiaxial thalli without secondary pit connections; carpogonial branches are 3-celled; auxillary cells are intercalary; carposporophytes almost entirely of carposporangia; tetrasporophytes small, tufted, producing zonate tetrasporangia (Saunders et al. 2004).
      • Nemastoma, Platoma, Schizymenia
    • ORDER PLOCAMIALES
      • Plants with 3-celled carpogonial branches with an intercalary supporting cell that acts like an auxillary cell (Saunders et al. 2004).
      • Pliocamium, Pseudoanemonia, Sarcodia
    • ORDER RHODYMENIALES
      • Multiaxial thalli; auxillary cell on a 2-celled filament (Graham and Wilcox 2000).
      • Champia, Fauchea, Lomentaria, Rhodymenia.