Pseudorthoceratid cephalopods from the Early Devonian Fukuji Formation of Gifu Prefecture, Central Japan

Seven species of Lochkovian (Early Devonian) pseudorthoceratid cephalopods are described and figured from the D1 member of the Fukuji Formation in Gifu Prefecture, central Japan. The fauna includes two pseudorthoceratines: Fukujiceras kamiyai gen. et sp. nov. and an indeterminate genus and species of the subfamily; four spyroceratines: Spyroceras fukujiense sp. nov., Spyroceras melolineatum sp. nov., Hamadaites labyrinthus gen. et sp. nov. and Mitorthoceras? kamitakarense sp. nov; and a cayutoceratine: Buchanoceras sp. The occurrence of Early Devonian pseudorthoceratids is first reported in Japan. The description of the new genera is made placing emphasis on ontogenetic variations, especially early juvenile shell morphology. The fauna may represent warm-temperate water conditions.