A new combination and two new species in the genus <i>Asterocladon</i> (Asterocladales, Phaeophyceae)

SUMMARY The brown algal order Asterocladales, which contains the single genus Asterocladon and is the sister order of the Ectocarpales, has stellate chloroplasts. We investigated newly established isolates of Asterocladon from southern/subtropical Japan to reveal their taxonomic positions based on morphological and molecular analyses using rbc L and psa A genes. An isolate of Asteronema breviarticulatum , which was so far classified in the Scytothamnales, was revealed to belong to Asterocladon , and thus Asterocladon breviarticulatum comb. nov. is proposed. Two other isolates of Asterocladon are described here as new species, Asterocladon iriomotense sp. nov. and Asterocladon discoideum sp. nov. Asterocladon iriomotense was characterized by small filamentous thalli having oligostichous parts, phaeophycean hairs, and globular masses on which plurilocular sporangia are formed. Asterocladon discoideum was characterized by small discoid thalli with phaeophycean hairs and globular or semiglobular masses, cells of which were differentiated into plurilocular sporangia.