Reproductive morphology of G astroclonium pacificum ( C hampiaceae, R hodymeniales) from J apan

Summary Morphological studies were undertaken on G astroclonium pacificum ( E . Y . D awson) C . F . C hang et B . M . X ia ( C hampiaceae, R hodymeniales) from J apan. We describe the details of male reproductive structures, the procarp and early post‐fertilization stages. This species has a solid axis, with both tetrasporangia and polysporangia, spermatangia are cut off from spermatangial parent cells, and a procarp is composed of a 4‐celled carpogonial branch and two 2‐celled auxiliary cell branches. The mature cystocarp lacks a conspicuous ostiole, a characteristic of the genus G astroclonium . The most distinctive characteristic of the species is the tela arachnoidea, which is lacking in other species of G astroclonium .