Fragilariforma javanica comb. nov.: analysis of type material of a widely reported species with a tropical distribution

Abstract

The transfer of Fragilaria javanica Hustedt to the genus Fragilariforma D.M. Williams & Round is presented based on a detailed analysis of the type material from Java (Malay Archipelago) using light and scanning electron microscopy. The taxon is characterized by each areola covered externally with a rota, well-developed, simple apical pore fields composed of rounded poroids and located on both valve apices, denticulate spines with tips oriented towards the apices, and open girdle bands with valvocopulae bearing heavily silicified advalvar fimbriae. These features are all shared with species currently ascribed to Fragilariforma, although the spine shape and orientation, and girdle elements having two rows of areolae, along with valvocopulae with well-developed fimbriae are typical of F. javanica. Morphological, ecological and distribution data are presented and discussed based on available literature for this taxon.

Keywords:

• diatoms
• Bacillariophyta
• Fragilariforma
• Fragilaria javanica
• Hustedt Collection
• taxonomy
• type material