The monophyly of the Archea is very much in dispute at this time. There are two or three recognized monophyletic groups within the Archea (Korarchaeota, Crenarchaeota, Euryarchaeota) and the dispute centers on where these groups go in the tree. The conservative alternatives would be (Taken from the TREE OF LIFE):
The "archaea tree":
,=============== Eubacteria
|
|
,== Euryarchaeota
=====| ,=Archaea=|
`==|
`== Crenarchaeota-Eocytes
|
`============
Eukaryotes
The "eocyte tree":
,======== Eubacteria
|
| ,===== Euryarchaeota
=====| |
`==| ,== Crenarchaeota-Eocytes
`==|
`== Eukaryotes
There are many references at the TREE
OF LIFE site on this and you are urged to consult them.