Abstract The four described species in the genus Campylaephora J. Agardh, tribe Ceramieae, namely, C. hypnaeoides, C. borealis, C. crassa and C. japonica, are known only from the western North Pacific. A new combination, C. californica, is proposed for plants referred to as Microcladia californica, originally described from syntype localities of California and Oregon. The species has alternate branching, six or seven periaxial cells per axial cell, internal rhizoidal filaments derived from periaxial and cortical cells, spermatangia formed from outer cortical cells, tetrasporangia developing from periaxial and inner cortical cells and covered by outer cortical cells, and naked carposporangia without involucral branchlets. Campylaephora is redefined to include species characterized by the presence of multiple layers of rhizoidal filaments derived from cortical cells that are linked by secondary pit connections. In our molecular study inferred from plastid-encoded rbcL sequence analysis, C. californica from ...