The variability and adaptability of the amoebae from the class Dictyosteliomycetes greatly complicate their systematics. The nucleotide sequences of the ribosomal internal transcribed spacers and the 5.8S ribosomal DNA gene have been determined for 28 isolates, and their utility to discriminate between different species and genera has been shown.This work was supported by grants CGL2005-00320/BOS, BMC02-01501, and BFU2005-00138 from the Dirección General de Investigación, Ministerio de Educación y Ciencia, Spain, and an I3P grant to M.R.Peer reviewed