Fungi as Fifth Kingdom?

[Ken Kinman]

Dear All,
      I define Kingdom Protista quite simply as all eukaryotes except for the two exgroups Metaphyta and Metazoa.  It is very similar to defining Reptilia as all amniotes except the two exgroups Aves and Mammalia.  Before birds and mammals arose, the only amniotes were reptiles.  And before Metaphytes and Metazoans arose, the only eukaryotes were protists.  It is interesting to look at the webpage of the International Society of Evolutionary Protistology:

http://megasun.bch.umontreal.ca/isep/isep.html

      Note that it for all those interested in the evolution and phylogeny of protists ("algae", "fungi", and "protozoa").  It simply does not make sense to me to split up all the "fungal" groups into different Kingdoms.  Whittaker split off Kingdom Fungi back in the 1960's, and yet Arthur J. Cain continued to include all fungal groups in Kingdom Protista (Encyclopaedia Britannica, 1975, Macropaedia Volume 4, page 690) in the classification of organisms used throughout that Encyclopaedia and in its reprintings for many years after 1975.  I suppose they eventually switched from 4 to 5 Kingdoms, but I can only hope that they never switched over to the Three Domain classification.

     As for Thomas Cavalier-Smith, he probably knows more about evolution and classification than any other person on the planet.  I am particularly impressed with his work on prokaryotic evolution and classification.  And he supports the use of paraphyletic taxa!!!  However, I think his classifications are unnecessarily inflationary.  I never saw any need to recognize a sixth Kingdom Chromista.  However, compared to the bloated Three Domain system (which he has criticized), Cavalier-Smith is relatively restrained.  I just wish he didn't feel the need to formally name every new grouping he finds (we are getting too much of that from the strict cladists).

     I looked at the NCBI taxonomy, and it has a Fungi/Metazoa Group, which is usually called Opisthokonta (actually I think it was Cavalier-Smith who named it back in the 1980's).  However, it should now include the Nucleariids, which were recently shown to be sister group to the "Fungi" (actually the true fungi or Eumycota).  This was in a paper coauthored by Baldauf (in the January 2006 issue of Molecular and Biological Evolution).  I don't recall how many Kingdoms were used by Baldauf et al., 2000 (the paper cited by Laura Katz), but I'd bet it was a lot more than Cavalier-Smith uses.  My differences with Cavalier-Smith are relatively minor, but still I don't approve of everything he does.
   -----Cheers,
             Ken Kinman