CLASS MESOSTIGMATOPHYCEAE

A group of motile or filamentous taxa. Motile cells with layers of scales. Chloroplast with or without eyespots. The class has 2 orders.

• ORDER MESOSTIGMATALES
  • Unicellular and motile; flagella inserted laterally in a crypt. Chloroplast cup-shaped with an eyespot in it. Cells covered by naviculoid scales.
  • Mesostigma.

• ORDER CHAETOSPHAERIDALES
  • Filamentous; motile cells with 1 layer of scales on surface and flagella. Chloroplast without eyespot.
  • Chaetosphaeridium.

CLASS CHLOROKYBOPHYCEAE

A clade of a single genus. The organism is nonmotile and sarcinoid (packets of cells that develop within persistent cell wall of the parent cell). The motile cells are biflagellate with the flagella inserted laterally from a groove (like a praesinophyte). Zoospores are covered by scales flagella with hairs.

• ORDER CHLOROKYBALES
  • Chlorokybus.

CLASS KLEBSHORMIDIOPHYCEAE

Unbranched filaments with parietal plate chloroplasts, superficially resembling members of the Ulotrichales. The zoospores resemble motile cells of Chlorokybus.

• ORDER KLEBSHORMIDIALES
  • Klebshormidium.

CLASS ZYGNEMATOPHYCEAE = CONJUGATOPSIDA (GAMOPHYTA OF MARGULIS AND SCHWARTZ 1998)

Filamentous or unicellular; reproduction involving conjugation between 2 cells; no flagellated stages; haploid, with zygotic meiosis; all fresh water. This class has 2 orders.

• ORDER COSMARIALES (DESMIDIALES)
  • Variously shaped unicells; usually 2 chloroplasts with nucleus sited between them; often with a narrow isthmus; mobility by mucilage secretion. “Desmids.”
  • Cosmarium, Micrasterias, Staurastrum, Hyalotheca, Desmidium, Closterium, Mesotaenium, Spirotaenia, Cylindrocystis, Netrium.

• ORDER ZYGNEMATALES
  • Unbranched, filamentous; varied forms of chloroplasts; cell wall usually slimy; conjugation results in resistant zygospore.
  • Zygnema, Spirogyra, Mougeotia.

CLASS CHAROPHYCEAE

Macroscopic; composed of very large cells forming rhizoids and stems with whorls of branches at nodes; growth takes place from an apical cell; cell walls may be heavily calcified; sexual reproduction by flagellated antherozoids and oogonia in complex oogonium; no zoospores. Zygotes develop into small protonemata that, in turn, produce the upright, gamete-bearing gametophyte.

• ORDER CHARALES.
  • Chara, Nitella, Nitellopsis, Tolypella.

CLASS COLEOCHAETOPHYCEAE

Prostrate, pseudoparenchymatous thallus with sheathed reproduction; oogonia protected by sterile cells; asexual reproduction by zoospores.

• ORDER COLEOCHAETALES.
  • Coleochaete.