After NCBI (National Center for Biotechnology Information)

<==o Desulfurococcales Huber & Stetter, 2002 [Igneococcales]
   |-- Desulfurococcales archaeon 121 
   |--o Desulfurococcaceae Zillig & Stetter, 1983 emend. Burggraf et al., 1997
   |  |-- Desulfurococcaceae str. SRI-465
   |  |--o Acidilobus Prokofeva et al., 2000
   |  |  |-- A. aceticus Prokofeva et al., 2000 
   |  |  |-- A. sp. 124-87
   |  |  |-- A. sp. 345-15
   |  |  |-- A. sp. 405-16
   |  |  `-- A. sp. 722-67
   |  |-- Acidococcus sulfurreducens
   |  |--o Aeropyrum Sako et al., 1996
   |  |  |-- A. camini Nakagawa et al., 2004
   |  |  `-- A. pernix Sako et al., 1996
   |  |--o Desulfurococcus
   |  |  |-- D. amylolyticus Bonch-Osmolovskaya et al., 2001
   |  |  |-- D. fermentans Perevalova et al., 2005
   |  |  |-- D. mobilis Zillig & Stetter, 1983
   |  |  |-- D. mucosus Zillig & Stetter, 1983
   |  |  |-- D. saccharovorans Stetter, 1986
   |  |  |-- D. sp. SEA
   |  |  |-- D. sp. SY
   |  |  `-- D. sp. Tok
   |  |--o Ignicoccus Huber et al., 2000
   |  |  |-- I. islandicus Huber et al., 2000
   |  |  |-- I. pacificus Huber & Stetter, 2000
   |  |  `-- I. sp. Kin4-I
   |  |--o Staphylothermus
   |  |  |-- S. hellenicus Arab et al., 2000 [Staphylothermus achaiicus]
   |  |  `-- S. marinus Stetter & Fiala, 1986
   |  |--o Stetteria Jochimsen et al., 1998
   |  |  `-- S. hydrogenophila Jochimsen et al., 1998
   |  |--o Sulfophobococcus Hensel et al. 1997
   |  |  `-- S. zilligii Hensel et al., 1997
   |  |--o Thermodiscus
   |  |  `-- T. maritimus Stetter, 2003
   |  `--o Thermosphaera
   |     `-- T. aggregans Huber et al., 1998
   `--o Pyrodictiaceae  Burggraf et al., 1997 [Pyrodictiales]
      |-- Desulfurococcales archaeon 121
      |--o Geogemma
      |  |-- G. indica
      |  `-- G. pacifica
      |--o Hyperthermus Zillig et al., 1991 
      |  `-- H. butylicus Zillig et al., 1991
      |--o Pyrodictium
      |  |-- P. abyssi Pley et al., 1991
      |  |-- P. brockii Stetter et al., 1984
      |  `-- P. occultum Stetter et al., 1984
      |--o Pyrolobus
      |  `-- Pyrolobus fumarii Blochl et al., 1999
      |--o Ignisphaera Niederberger et al., 2005
      |  |-- I. aggregans Niederberger et al., 2005
      |  |-- I. sp. Tok1
      |  |-- I. sp. Tok10A.S1
      |  `-- I. sp. Tok37.S1
      `--o Caldococcus
         `-- C. noboribetus Aoshima et al., 1996

Special thanks to:

Nils Hartmann, for collecting this information and species.

Reference(s):