KARYOLOGY AND NUCLEAR-DNA QUANTIFICATION IN BRYOPSIS (CHLOROPHYTA) FROM NORTH-CAROLINA, USA

Chromosome numbers for three species of Bryopsis (Codiales, Chlorophyta) from the warm temperate coast of North Carolina are presented. Bryopsis hypnoides Lamouroux, and B. plumosa (Hudson) C. Agardh have chromosome complements of 1 N = 10, while in B. pennata Lamouroux 1 N = 8. The results obtained by microspectrophotometry with the DNA-localizing fluorochrome hydroethidine, and karyotype comparisons, failed to distinguish B. hynoides and B. plumosa. By contrast, regional isolates of B. pennata all had a significantly smaller genome than the above species. In B. hypnoides, identical I(f) values for nuclei in gametes and vegetative macrothalli confirmed the mitotic nature of gametogenesis. A small ( < 10%) but constant number of these gametes were binucleate, with nuclei having a 1C amount of DNA. In addition, nuclei in older main axes were apparently endopolyploid, with I(f) values indicative of 4CDNA levels. Incorporation of microspectrophotometric data for two angiosperms with known 2C DNA contents permitted quantification of I(f) values for Bryopsis plants. Extrapolated 2C DNA contents for B. hypnoides B. plumosa, respectively, are 1.0 pg and 0.7 pg for B. pennata. It is concluded that Bryopsis is represented by two species in North Carolina: B. pennata, and a second entity whose morphotypes have been referred variously to B. hypnoides and B. plumosa.