Introduction
The dictyostelid cellular slime molds are soil amoebae that can lead both unicellular (i.e. solitary) and multicellular (i.e. social) lives. Single amoebae feed on bacteria, grow and divide by mitosis. When starvation sets in, they stop dividing, aggregate and form an integrated multicellular unit, the slug, which exhibits division of labour. Eventually, some amoebae differentiate into dormant spores and form a coalescent mass, the sorus. The remaining amoebae form a dead cellular stalk and support the sorus; the whole is called a fruiting body (Bonner 1967).
Dictyostelid cellular slime molds (dictyostelids) are common components of the soil/leaf litter interface, particularly in tropical, subtropical and temperate regions (Landolt & Wong 1998). They are usually present and often abundant in terrestrial ecosystems and apparently play a role in maintaining the natural balance that exists between bacteria and other microorganisms in the soil environment (Landolt et al. 2006a). Most of the life cycle of a dictyostelid is spent in a unicellular, amoeboid state,with cells feeding upon bacteria, protists, and microfungi. When such food supplies are abundant, slime mold myxamoebae proliferate by mitotic cell division. As the local bacterial food supply becomes relatively depleted, hundreds to thousands of myxamoebae, responding to chemotactic signals, aggregate and collectively differentiate as a sorocarp.
The sorocorp consists of vacuolated cells, with cellulosic cell walls, which form a branched stipe with a cluster of spores at each stipe terminus (Landolt & Wong 1998, Bonner 2009).