Volume 50, Issue 4

Classification of the red algae (Rhodoplantae) has undergone significant change since the seminal work of Harald Kylin, “ Die Gattungen der Rhodophyceen ,” a half century ago. The number of genera has nearly doubled over this time period, at least in part due to recent molecular comparative work. Information gleaned from gene-sequencing analyses has resulted in a red algal classification that reflects a more accurate phylogenetic framework than that based solely on morphological data. This paper tabulates the known 834 genera of red algae today with taxonomic synonyms and literature references reflecting the great change over fifty years.

Molecular studies were carried out on Chondrophycus gemmiferus and C. poiteaui (Rhodomelaceae) from the Mexican Caribbean Sea. These species are morphologically related, but differ mainly in the presence of the apiculate projection of epidermal cells near the apices of branches. Both species belong to Chondrophycus, as indicated by the presence of two periaxial cells per axial segment and a 90° arrangement of tetrasporangia, but share characteristics with Laurencia species (e.g., presence of secondary pit connections between adjacent epidermal cells). The phylogenetic position of these species was inferred by an analysis of chloroplast-encoded rbc L gene sequences of 21 taxa, using two members of the Rhodomelaceae and two of the Ceramiaceae as outgroups. The results corroborate the taxonomy of the Laurencia complex, which comprises the genera Laurencia, Chondrophycus and Osmundea , and indicate that rbc L provides an adequate phylogenetic signal to study the intergeneric and interspecific relationships within the complex. In spite of this, relationships within the clade formed by C. gemmiferus and C. poiteaui were not resolved by any analysis because of the low level of genetic variation between their rbc L sequences (0.01–0.02%). On the basis of both molecular data and morphological similarities, we concluded that C. gemmiferus should be considered as a variety of C. poiteaui and the following new combination is proposed: Chondrophycus poiteaui var. gemmiferus (Harvey) comb . et stat. nov.

The occurrence of meiosis in the life cycle of the heteromorphic dioecious marine red alga, Porphyra haitanensis , is described. Chromosome numbers indicated that conchosporangial cells and conchospores are diploid (2n=10), while two- and three-celled stages of conchospore germlings, vegetative cells and spermatia of the gametophytic blades are haploid (n=5). We observed karyological changes in leptotene, zygotene, pachytene, diakinesis, metaphase and anaphase of the meiosis, and the change in ploidy at the two-celled stage of conchospore germling. Characteristics of the first division of the conchospore and the change in ploidy at the two-celled stage indicated that meiosis I occurs during the germination division of conchospore in this species.