Algae. 1988; 3(2): 89-93.

Interoceanic Hybridization in Fully Corticated Ceramium Isolates ( Rhodophyta ) from Nova Scotia and Washington

David Garbary

Department of Biology, St. Francis xavier University

Four independent isolates of a fully corticated Ceramium (cf. Ceramium rubrum) from eastern and western North America completed their life histories in unialgal culture with a Polysiphonia-type life history. Two isolates from Washingtion State (Fidalgo Island and San Juan Island) were partially interfertile, while two isolates from Nova Scotia did not form hybrids. One Washington isolate (Fidalgo I.) and one Nova Scotia isolate (Pomquet Hbr.) formed successful hybrids. Reciprocal crosses between these isolages produced viable carpospores, and the hybrid was successfully cultured through three complete Polysiphonia-type life histories. The first generation of gametophytes also produced viable backcrosses with parental material. These results confirm the conspecificity of a Ceramium species from the Pacific and Atlantic Oceans and provide the first example of interoceanic hybridization in red algae.

Keywords : Ceramium C. rubrum, hybirdization, biosystematics, Rhodophya, taxonomy