In the modern marine environment the silicoflagellate genus Dictyocha is rare, or absent, south of the Antarctic polar front (APF); the genus Distephanus, in contrast, is dominant. In sediments recovered from ODP Site 1165, 1600 km south of the front, however, three intervals where Dictyocha is abundant are interpreted to represent Pliocene warm events. Dictyocha is absent from other Site 1165 Pliocene intervals, which suggests that cooler SST prevailed. The warm events detected at Site 1165 may represent times when North Atlantic Deep Water production and ocean heat transport into the Southern Ocean exerted maximum influence. (mod. journ. abstr.)