The southern Chilean archipelago and fjordland (41-52 degrees S) thus far is very poorly investigated also with regard to its nudibranch fauna. This study presents the first records Of nudibranchs from remote islands of the Chonos archipelago exposed to the open Pacific. Collecting data and some biological observations are given for the doridoidean Archidoris fontaini, Diaulula punctuolata and Rostanga pulchra. Taxonomically relevant external and radular characters of R. pulchra are redescribed and compared with literature data oil conspecifics from Argentina and California. The bipolar, cold-water adapted R. pulchra is critically compared with the western Atlantic, warm-water adapted R. byga. New distributional data indicates that the Chiloe Island area (41-43 degrees S) does not represent a strict southern distributional barrier for warm-temperate eastern Pacific nudibranch species but is at least partly Clue to collecting bias.