Stramenopiles

The stramenopiles are one of the main groups of eukaryotes, including the giant multicellular brown algae, the planktonic diatoms, and most other algae of similar pigmentation, as well as similar heterokont flagellates, the fungus-like water molds and other colorless forms. All forms have mitochondria with tubular cristae and show open mitosis. The group is mainly distinguished, though, based on the characteristic structure that the flagella have when present.

A number of basal stramenopiles are flagellates, and multicellular forms still typically produce motile zoospores. Almost all of these have two unequal flagella, one supporting tiny mastigonemes (hairs), and the other smooth and usually shorter. These lie off to the side, and typically have four microtubule roots. Such cells are called heterokont, and are distinct to the group. Also, mastigonemes whenever present have a unique tripartite structure.

The primitively colorless stramenopiles include the following groups:

• Bicosoecids?, a line of heterokont flagellates
• Proteromonads? and Opalines?, flagellates, the latter comprising multinucleate forms with flagella in rows across the body
• Oomycota? (water-molds) and Hypochytridiomycota?, forms similar to fungi
• Labyrinthulids? and Thraustochytrids?, two groups of slime molds

After these, all stramenopiles are photosynthetic or secondarily colorless. The chloroplasts contain the chlorophylls a and c and the pigment fucoxanthin. They are bound by four membranes, suggesting that they are reduced form of some endosymbiont alga, but unlike the chloroplasts in the cryptomonads there is never any remaining nucleomorph. These include various basal groups, collectively referred to as [golden algae]? (Chrysophyta), together with the following:

• Diatoms
• Raphidophyta?
• Eustigmatophyta?
• Xanthophyta? (yellow-green algae)
• Phaeophyta? (brown algae)

These last two lists ought to be revised, completed, and probably expanded into surveys. Right now, though, I'm going to leave them, and would need to know more about golden algae anyways to split them up properly.