Remarks on the Audouinella microscopica (Näg.) Woelkerling complex, with a brief survey of the genus Chromastrum Papenfuss (Rhodophyta, Nemaliales)

Observations are presented on the life histories and morphological variability of Swedish material of Chromastrum moniliforme (Rosenvinge) Papenfuss and Chromastrum collopodum (Rosenvinge) Papenfuss. The life history of C. moniliforme fits in with the general pattern of the genus Chromastrum, showing a combination of a gametophyte with a unicellular base and a tetrasporophyte with a septately germinating spore and a multicellular base. The same holds true for C. collopodum, except that in the tetrasporophyte the germination is occasionally aseplate. It is concluded that the nature of variation between some members of the Audouinella microscopica (Nag.) Woelkerling complex is largely genotypic, and our work does not support the hypothesis of their conspecificity. In addition, a brief survey is given of the genus Chromastrum Papenfuss, with an evaluation of most morphotaxonomic characters. Some 60 described species are presently thought to belong to this genus. A considerable reduction of this number must be anticipated for two reasons: first, generations of one life history have usually been described as two different systematic entities; second, morphologically similar species may prove conspecific, in view of the variability of some characters in culture. The genus Chromastrum is cosmopolitan, with probably a maximum diversity in the North Atlantic Ocean, and a low representation in tropical seas.