Systematics and Evolution, Part A The Mycota

fruiting body consists of a stalk that may dis-

play branching and one or more sori of spores

(Fig.2.3). Aggregation and fruiting represent an

asexual dispersal process, but sex is known

for many species (Raper 1984 ; Cavender 1990 ;

Kessin 2001 ). The latter involves the formation

Fig. 2.2Aggregation center (right) and early developing fruiting bodies (left)ofPolysphondylium tenuissimum

(photo by Andy Swanson). Scale bar¼0.5 mm

Fig. 2.3Fruiting body ofDictyostelium sphaerocephalum(photo by Andy Swanson). In this species, the fruiting
body consists of a stalk with a single sorus at the top. Scale bar¼0.3 mm

24 S.L. Stephenson