0023-6152

AA00697606

25199

査読無

0023-6152

AA00697606

Detailed morphological study on the plants of the Gracilariaceae around the Hakata Bay, northern Kyushu, Japan revealed that five species of the family were recognizable in this area. According to the previous description, they were assignable to Gracilaria chorda, G. cuneifolia, G. parvispora, G. textorii and G. vermiculophylla. Of these, only G. chorda was separated from the other four species by its lack of spermatangial cavities and nutrient tubular cells in cystocarps. As rbcL gene sequence analyses and the resultant phylogenetic trees (maximum parsimony, maximum likelihood, Bayesian inference) support this distinction, the four species were retained in the genus Gracilaria while G. chorda was considered to belong to Gracilariopsis, a genus that consists of species with superficial spermatangia and without nutrient tubular cells. In our phylogenetic trees, G. vermiculophylla was recovered as a basal species to all other Gracilaria species, which were positioned in the same evolutionary lineage. Interestingly, our specimens of G. vermiculophylla showed a mixture of spermatangial conceptacles, monocavitied (the verrucosa type) and multicavitied (the polycarvernosa type) on the same blade. However, the multicavitied conceptacle is a major character of other genus Hydropuntia within the Gracilariaceae. Further studies are thus necessary to clarify the relationship among these genera and to establish a better classification system of the family.