Seasonal development of five C ephaleuros species ( T rentepohliaceae, C hlorophyta) on the leaves of woody plants and the behaviors of their gametes and zoospores

Summary The infection cycle of five C ephaleuros species – C . aucubae , C . biolophus , C . japonicus , C . microcellularis , and C . virescens – was clarified by investigating seasonal development and gamete and zoospore behavior at study sites in M atsue, S himane P refecture, J apan. Fresh thalli or lesions appeared on the leaves of various woody plants from A ugust and continued to develop in general from A pril to S eptember in the following year. Gametangia and zoosporangia matured on 2‐ and 3‐year‐old leaves. Gametes were released in C . microcellularis samples collected from late M arch to late M ay and in samples of the other four species collected from late A pril to late J uly. Zoospores were released in C . biolophus, C . japonicus , and C . virescens samples collected from mid‐ M ay to early A ugust. In the present study, gametes did not conjugate but germinated like zoospores to produce new plants. After inoculation with zoospores and gametes that behave as asexual spores, fresh thalli or lesions became evident in 2–5 months following inoculation and gametes and zoospores were produced on the developed thalli or lesions the following year; one cycle of the infection was completed per year in the study area.