The Red Algal Epiphytes Microcladia Coulteri and M. Californica (Rhodophyceae, Ceramiaceae). I. Taxonomy, Life History and Phenology1

In the northeast Pa@, there are two epiphytic species of the genus Microcladia Grev. Microcladia coulteri Ham. grows on a wide range of red algal and occasionally brown algal basiphytes whereas M. californica Farl. grows only on the brown alga Egregia menziesii (Turn.) Aresch. Although both are obligate epiphytes in the field, they complete their life history in culture in the absence of their respective basiphytes. Along the coast of central California, M. californica exhibits distinct seasonal patterns in reproduction whereas M. coulteri does not. In addition to previously documented daferences in cystocarp development and branchlet patterns, the two taxa can be delineated by differences in spore sizes, timing of spore attachment and morphology of the primary rhizoid. The haploid chromosome number for both species ranges from 14‐16. Attempts to hybridize the two species have been unsuccessful. In addition, restriction fragment length polymorphism analyses of the plastid DNA of the two species provides further evidence that Microcladia coulteri and Microcladia californica represent distinctive species.