Morphological investigations of Achnanthes javanica grunow and A. subconstricta (Meister) comb. nov

The morphology and fine structure of two marine mooraphid diatoms, Achnanthes javanica Grunow and A. subconstricta (Meister) comb. Nov. (= A javanica var. subconstricta Meister) have been investigated. Observations on the valves of type material (Grunow in Cleve & Moller 1878) of A. javanica show them to be lanceolate to linear in shape with a marginal ridge on the araphid valve but lacking terminal orbiculi. Conversely, A. subconsticta has a marginal ridge and special marginal spines as well as terminal orbiculi. From SEM observations in girdle view, A. subconstricta. These features support the view that A. subconstricta should be considered an independent species.