Iranognathus sosioensis n.sp., a Changxingian (latest Permian) conodont species of western Sicily, is the youngest Iranognathus species occurring immediately below the Permian-Triassic boundary. The Middle Permian and part of the Late Permian pelagic conodont faunas of western Sicily are cold bottom-watter faunas, very dif ferent from the contemporaneous pelagic warm water faunas . The facial pretensions of I. sosioensis are not yet known.