Myxomycete biosystematics: various Didymium and Physarum species
Clark, Jim; Landolt, John C.
Nine isolates of Didymium anellus, two isolates of D. saturnus, one isolate of D. laxifilum, five isolates of Physarum cinereum, and three isolates of P. pusillum were grown from spore to spore in culture and their reproductive systems determined. Of these 20 isolates, only two D. anellus isolates (PR 3, PR 4) were heterothallic, with the remainder of the isolates being nonheterothallic. However, the mating type testers of the two heterothallic D. anellus isolates did not cross and therefore the two isolates belong to different biological species. Plasmodial fusion tests between the nonheterothallic (presumptive apomicts) isolates of each species showed that fusions only occurred between isolates derived from adjacent sites, which indicates that these species probably consist of a large number of genetically independent clonal lines.