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Abstract
The morphology, life histories and crossability in culture are described for the marine red algae Chondrus ocellatus Holmes forma ocellatus from Japan, China and Korea and C. ocellatus f. crispoides Mikami (Gigartinaceae, Rhodophyta) from Japan. In culture, all isolates of both formae showed a Polysiphonia-type life history typical of the family Gigartinaceae. Plants of C. ocellatus f. ocellatus from Korea and China and some strains from Japan formed gametangia under long-day conditions (LD) at 15°C; however, two other Japanese strains required short-day conditions (SD) at 15°C for gametogenesis, indicating a photoperiodic response. Plants of C. ocellatus f. crispoides did not require SD for gamete formation. In all strains, tetrasporophytes of both formae produced tetrasporangia under LD. Isolates of C. ocellatus f. ocellatus from Japan, China and Korea were found to be completely sexually compatible regardless of photoperiodic characteristics, and the responses to daylength shown by progeny of LD and SD strains suggested Mendelian inheritance of a daylength factor. Chondrus ocellatus f. ocellatus was sexually incompatible with C. nipponicus Yendo, a morphologically similar species from Japan, but C. ocellatus f. crispoides was partially interfertile with both C. ocellatus f. ocellatus and C. nipponicus, indicating that the three entities are closely related. In view of the apparently higher breeding compatibility between C. nipponicus and C. ocellatus f. crispoides, and the fact that these two entities are more similar morphologically and reproductively, it is proposed, provisionally, to refer C. ocellatus forma crispoides to C. nipponicus.
