Niel sen, K. S. S. 2015. In de fence of an iconic ichnogenus -Oichnus Bromley, 1981. Annales Societatis Geologorum Poloniae, 85: 445-451. Ab stract: By es tab lish ing the bioerosion ichnogenus Oichnus, Rich ard Bromley (1981) ad dressed 'small round holes in shells' and catalysed a se ries of still on go ing dis cus sions on ichnotaxonomical prin ci ples. In a re cent re vi sion by Zonneveld and Gingras (2014) , Oichnus was re jected, to gether with Tremichnus Brett, 1985 and Fossichnus Niel

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... n, Niel sen and Bromley, 2003, by means of sub jec tive synonymisation with the pre sumed se nior syn onym Sedilichnus Müller, 1977. How ever, Sedilichnus is nomenclaturally un avail able, be cause it is an atelonym (con di tion ally pro posed). In ad di tion, re in ves ti ga tion of the type ma te rial of 'Sedilichnus' shows that it prob a bly de scribes vari ably shaped oscula and thus is a gen u ine mor pho log i cal char ac ter of the host sponge Prokaliapsis ja nus, rather than a bioerosion trace fos sil. The ichnogenera Oichnus and Tremichnus are re vised, lead ing to the synonymisation of Balticapunctum Rozhnov, 1989 with Tremichnus, and of Fossichnus with Oichnus. The re fined ichnogeneric di ag no ses re turn Oichnus to com plete or in com plete bioerosive pen e tra tions in cal car e ous skel e tal sub strates, com monly in ter preted as praedichnia with or with out signs of at tach ment, while Tremichnus (now in clud ing O. excavatus) ex clu sively re fers to shal low pits pass ing into echinoderm skel e tons that are in ter preted as domichnia or fixichnia.