ABSTRACT
The myxomycetes (plasmodial slime molds or myxogastrids) are a group of eukaryotic microorganisms that belong to the supergroup Amoebozoa (Adl et al., 2012). Their phylogenetic position is currently supported by molecular studies that clearly show their monophyletic character within the Amoebozoa (see Pawlowski and Burki, 2009). In the past, myxomycetes usually have been considered as members of a group known as the Eumycetozoa (Olive, 1975). This hypothetical group included, along with the myxomycetes, two other groups of amoebae known as dictyostelids and protostelids (also called protosteloid amoebae). However, the integrity of the Eumycetozoa as a natural group has been questioned recently on the basis of molecular evidence indicating that the protostelids are probably not monophyletic (Shadwick et al., 2009). This fact does not affect the currently recognized position of myxomycetes within the Amebozoa, but it changes the concepts and nomenclatural treatments of the particular subgroups of organisms to which they are related. Given this situation and for the purpose of this chapter, myxomycetes simply will be treated herein as a group of amoebozoans taxonomically distinct from both dictyostelids and protostelids.
