Taxonomic and Molecular Phylogenetic Studies of Amphioxus: A Review and Prospective Evaluation

Amphioxus, as the closest living animal of the last common ancestor of all vertebrates, occupies an extremely important phylogenetic position in the evolution of vertebrates and has attracted the interest of scientists from various research fields in recent years. However, despite their importance for the life sciences, taxonomic studies of amphioxus are relatively limited. In present review, we summarize current progress in both field investigations and taxonomic research of Chinese amphioxus. Based on the investigation data, we assume that amphioxus is distributed in all habitable sandy beaches along the Chinese coast from south to north. According to the rule of priority and recent taxonomic studies on amphioxus, we also propose that the original subspecies Brnachiostoma belcheri tsingtauense together with the population in most Japanese waters is an independent species and its name should be revised to B. japonicus. Consequently, there are at least two species of genus Brnachiostoma and 1-3 of Epigonichthys and one of Amphioxides in the China Sea. Finally, the application of DNA molecular markers in systematic studies of cephalochordate is evaluated.