Abbott has two different species in Hawaii, but both have been transferred to other genera. The Micronesian species are not in IOC . Centroceras axes are fully corticated. There are numerous species of Polysiphonia in Micronesia, as most places. Photo below compares these two genera.
Photo below shows a mature cystocarp with carpospores.
The plant is a female gametophyte. Rhodomelaceae Chondria specimens we have seen resemble Herposiphonia in habit, but are corticated . Larger species may be mistaken for Laurencia. It also has apical depressions with clusters of hairs arising from them. The diagram below illustrates this.