MORPHOLOGICAL AND MOLECULAR INVESTIGATIONS OF NAVICULOID DIATOMS. II. SELECTED GENERA AND FAMILIES

Abstract

A molecular analysis of 91 species of naviculoid diatoms representing 22 genera and 72 species using three different molecular markers was performed. Support was found for many groups established by traditional morphological methods. Gomphonema, Cymbella, and Encyonema were recovered as monophyletic groups. Cymbelloid diatoms were divided into two clades, which corresponded to the genera of Cymbella and Cymbopleura. Gomphonema was also divided into two groups based on external areolae coverings. Amphora was not monophyletic and the two groups recovered corresponded to the subgenera Amphora and Halamphora. Fresh water and marine monoraphids did not form a monophyletic group, although individual genera were monophyletic. Mayamaea was consistently recovered as the sister taxon to a Pinnularia/Caloneis clade. Craticula and Stauroneis were also consistently recovered as sister taxa, but the addition of Navicula intergra to the base of the Stauroneis clade suggested that a new genus was warranted to accommodate this taxon.

Keywords:

• naviculoid diatoms
• rRNA phylogeny