FINE STRUCTURE AND TAXONOMY OF SYNEDROPSIS KARSTETERI SP. NOV. (FRAGILARIACEAE, BACILLARIOPHYTA), A BLOOM-FORMING, BRACKISH-WATER, PLANKTONIC, ARAPHID DIATOM FROM PERDIDO BAY, NORTHEASTERN GULF OF MEXICO

Abstract

Dense cell concentrations of a brackish-water, araphid diatom, Synedropsis sp., collected in the summers of 1995 and 1996 from Perdido Bay, northeastern Gulf of Mexico, afforded an opportunity to examine the structure of the frustule in detail and to identify this bloom-forming species as Synedropsis karsteteri sp. nov. It is characterized by the presence of two elongated plastids, a single rimoportula per valve and the apical slit fields, each consisting of 2–3 slits. The morphology and taxonomy of the new species is discussed and compared with the generitype, S. hyperborea, and other species, including S. roundii. A dichotomous key to the identification of all currently described Synedropsis species is also provided.

Key words:

• Apical slit field
• Florida
• Diatom taxonomy
• Gulf of Mexico
• Perdido Bay
• Rimoportula
• Synedropsis