Morphology and taxonomy of toxic species in thetamarensisgroup (Dinophyceae):Alexandrium excavatum(Braarud) comb. nov. andAlexandrium ostenfeldii(Paulsen) comb. nov.

Publisher Website
Google Scholar
Abstract
Using light microscopy and scanning electron microscopy the thecal and internal morphology of two taxa within the Gonyaulax tamarensis complex were investigated based on material collected in Oslofjorden, Norway. Combined with Braarud's unpublished information on his type material the observations indicate that the taxa are identcal with Gonyaulax tamarensis LEBOUR var. excavata BRAARUD and G. tamarensis var. globosa BRAARUD which were described from Oslofjorden. Based on observations on infraspecific variations it is proposed that the genus concept of Alexandrium HALIM is extended to include species with direct contact between the plates Po and 1′ and the new combinations Alexandrium excavatum (BRAARUD) comb. nov. and Alexandrium ostenfeldii (PAULSEN) comb. nov. are proposed. Their plate formula is: Po, 4′,6″, 6C, 9-10S, 5′″, 2″″ which includes one or two small accessory sulcal plates. Both species have a characteristic tabulation including a ventral pore. A. excavatum and probably A. ostenfeldii produce paralyzing shellfish toxins. New combinations for the related species Alexandrium peruvianum (BALECH & MENDIOLA) comb. nov. and Alexandrium depressum (GAARDER) comb. nov. are proposed.