Ecological potentials of species of Rozella (Cryptomycota)

Parasites in the Phylum Cryptomycota and their hosts in the Phyla Chytridiomycota, Blastocladiomycota and Oomycota have commonly been observed in aquatic and soil ecosystems. Although rDNA sequence data from environmental samples suggest a wide genetic diversity for the Cryptomycota, Rozella is the only genus described in this group. The species of Rozella which have been studied in the laboratory are biotrophs and have stages with simple morphological characteristics in their life cycles. The life cycles consist of uniflagellate zoospores, thalli which are unwalled, endobiotic protoplasts, and sometimes walled resting spores. These parasites are secondary consumers in producer and detritus based food chains. Species of Rozella efficiently transfer carbon and energy from their hosts (primary consumers) to grazing zooplankton and other tertiary consumers. It is likely that they fine-tune the dynamics of food chains and increase the complexity of food webs. However, there are no quantitative data available at present to support this hypothesis.

► Rozella is the only genus described in the Cryptomycota.
► All known species are endobiotic biotrophs.
► Hosts include zoosporic true fungi and heterotrophic stramenopiles.
► Species are widespread in environmental rDNA samples.
►  Possible roles in food webs and population dynamics are discussed.