Phylogenetic position of eight Amphora sensu lato (Bacillariophyceae) species and comparative analysis of morphological characteristics

Amphora Ehrenberg ex Kutzing sensu lato is a common and widespread benthic diatom genus with a taxonomy that has been under continual revision, particularly based on molecular analyses. Although Amphora species have been studied using modern microscopy in recent years, there has not been much progress on molecular characterization of the species, especially in Asia. In this study of Amphora, sampling was carried out from September 2009 to August 2010 in Korean coastal waters. The morphological and molecular characteristics of eight Amphora sensu lato were examined: Amphora marina, A. proteus, Halamphora costata, H. coffeaeformis, H. eunotia, H. holsatica, H. terroris, and Halamphora sp. Based on previous accounts, morphology suggested that, A. marina and A. proteus belong to the subgenus Amphora Cleve, which have smooth girdle bands and rather coarse and very distinct areolae on the valve. In agreement with analysis based on morphological characteristics, phylogenetic analysis based on small subunit rDNA suggested that, the eight Amphora sensu lato species were not a monophyletic group as the morphological classification.