Psamathe Johnston, 1836 is valid as Psamathe Rafinesque, 1814 in Isopoda is a nomen nudum fide Holthius (1954) and Nomenclator Zoologicus, and Psamathe Philippi 1840 in Copepoda is junior. However, McIntosh (1908:130) had revived Kefersteinia because of this apparent homonymy. Pleijel (1998:124) discusses this matter.
Pleijel, Fredrik 1998. Phylogeny and classification of Hesionidae (Polychaeta). Zoologica Scripta, 27(2): 89-163, 38 figures, 7 tables.