Twenty-eight species of scale-bearing nanoflagellates from southern Tasmanian waters are illustrated and discussed (excluding the haptophyte Chrysochromulina , previously reported (LeRoi and Hallegraeff 2004), and coccolithophorids). Scale morphologies of both field samples and enrichment cultures were examined using transmission electron microscopy. Predominant species included the chrysophyte Paraphysomonas imperforata , the prasinophyte Pyramimonas grossii , and haptophytes Phaeocystis globosa and Imantonia rotunda . There were nine new records for Australian waters: the chrysophytes Chrysolepidomonas marina , Paraphysomomas antarctica , P. bandaiensis , P. foraminifera , P. cf. takahashii , Petasaria heterolepis , Thaumatomastix cf. thomsenii , and the prasinophytes Dolichomastix cf. tenuilepis and Mamiella gilva . Two potentially harmful haptophyte species, Phaeocystis globosa and Prymnesium parvum f. patelliferum , responsible for bloom events and fish mortalities, particularly in the northern hemisphere, were also found. The present survey adds further evidence for the apparent cosmopolitanism of many scale-bearing nanoflagellate species.