ABSTRACT: Prymnesium neolepis was collected from surface and sub-surface waters of the Southern Indian Ocean. It is characterized by the presence of broad 0.6 ym-1ym, recurved poreless brim (collar), and small sized numerous pores (0.1-0.2ym size, 180-240 pores) in the bulging central area of hat-shaped siliceous scale. It was observed in the subtropical and subantarctic frontal regions (0-110m depth) and in surface waters up to 60°S. It is neither recognizable in the fossil record nor bottom sediments and also shows close affinity with siliceous scales of extant Petasaria heterolepis. Further studies focusing on culture, accessory pigments and phylogenetic-molecular aspects could reveal better understanding of this rare siliceous and other unmineralized scale bearing Haptophyte.