Circumscription of the order Ectocarpales (Phaeophyceae): bibliographical synthesis and molecular evidence

Phylogenetic analyses of 27 brown algae including the type genera of the orders Chordariales, Dictyosiphonales, Ectocarpales sensu stricto, and Scytosiphonales, using partial SSU + LSU combined rDNA sequence data, supports a broadly circumscribed order Ectocarpales. This order is redefined to include taxa possessing an exserted, pedunculated pyrenoid. Previous then taxa were placed in the Ectocarpales sensu stricto, the Chordariales, the Dictyosiphonales, or the Scytosiphonales. Algae either lacking a pyrenoid, and sometimes included in the Ectocarpales (Tilopteridales, Ralfsiales sensu Nakamura), or which possess a non-pedunculated pyrenoid (such as those placed in the recently proposed order Scytothamnales, as well as Asteronema, Asterocladon and Bachelotia), are excluded from the Ectocarpales. (C) ADAC/Elsevier, Paris.