Mycology 427R/527R
Fall 98
(modified from Dr. R. L. Gilbertson)
 
 
 
 
The Position of "Fungi" in the Classification of Living Organisms

In our system of classification of living organisms six kingdoms will be recognized. These are: 
 

Prokaryotae 
Protoctista 
Stramenopila 
Fungi 
Plantae 
Animalia 
Three of these, Prokaryotae, Plantae, and Animalia, do not contain any groups of organisms traditionally recognized as fungi. They will not be considered further here. The inclusion of the Stramenophila is a relatively new classification scheme where organisms that have cellulosic cell walls and tinsel flagella are in a separate kingdom. 
 
Key to Kingdoms containing taxa traditionally considered to be Fungi

1. Cell wall absent in the vegetative stage, which is a plasmodium or 

a pseudoplasmodium ...................................................................... PROTOCTISTA 

1. Cell wall present in vegetative stage ..................................................................... 2 

2. Motile cells, if present, heterokont with whiplash and tinsel flagellae; cell walls with cellulose; sexual reproduction by gametangial contact or isogamy ................................................................................... STRAMENOPILA 

2. Motile cells, if present, isokont with a single posterior whiplash flagellum; cell wall with chitin and glucans other than cellulose; sexual reproduction by isogamy, gametangial fusion, gametangial contact, spermatization, conidiation, or somatogamy................................................................................... FUNGI 
 
 

Key to Phyla of "fungi" in Kingdom Protoctista

1. Vegetative stage a multinucleate plasmodium ......................................................... 2 

1. Vegetative stage a multicellular pseudoplasmodium .................................................. 3 
 

2. Plasmodial stage free-living .......................................... MYXOMYCOTA 

2. Plasmodial stage parasitic in cells of host ..........PLASMODIOPHOROMYCOTA
 

3. Pseudoplasmodium developing after aggregation stage with myxamoebae streaming into a central point; myxamoebae with filose pseudopodia.....................................................DITYOSTELIOMYCOTA
3. Pseudoplasmodium developing after aggregation stage without streaming; myxamoebae with lobose pseudopodia .........................................................................ACRASIOMYCOTA 
 
 
Key to Phyla of "fungi" in Kingdom Stramenopila
 
1. Thallus a network of branched tubes within which amoeboid cells crawl ................................................................................... LABYRINTHULOMYCOTA 

1. Thallus single celled or filamentous with coenocytic hyphae........................................... 2 
 

2. Thallus single-celled or rhizoidal; motile cells with a single anterior tinsel type flagellum ...................................................... HYPHOCHYTRIOMYCOTA 
2. Thallus filamentous with coenocytic hyphae or rarely single-celled or holocarpic; motile cells heterokont with whiplash and tinsel flagellae; thallus diploid with gametangial meiosis ..........................................................................................OOMYCOTA   
Key to Phyla of "fungi" in Kingdom Fungi
 
 
1. Thallus single-celled or with a rhizoidal pseudomycelium; motile cells with a single posterior whiplash flagellum ...................................................................CHYTRIDIOMYCOTA 

1. Thallus mycelial (or single-celled in yeasts); no motile cells; hyphae septate ........................ 2 
 

2. Asexual reproduction by aplanospores developing in sporangia or conidia; sexual spores diploid, zygospores ................................................ ZYGOMYCOTA 
2. Asexual reproduction by conidia; sexual spores either ascospores or basidiospores or unknown .............................................................................................. 3
 
3. Sexual spores unknown ............................................................ DEUTEROMYCOTA 

3. Sexual spores produced .................................................................................... 4 

  4. Sexual spores ascospores in an ascus; dikaryon a short-lived, non free-living stage immediately preceding ascus development ..................................... ASCOMYCOTA 

4. Sexual spores basidiospores on a basidium; dikaryon a free-living vegetative stage..............................................................................BASIDIOMYCOTA

(The DEUTEROMYCOTA or "Fungi Imperfecti" are presumed to be ASCOMYCOTA for which the phylogenetic relationships will be eventually established by DNA homologies. Until that has been accomplished there will be a practical need to maintain this taxon as a phylum of Fungi) 
 To top of the key | back to Syllabus