Stebbing (1900) gave a very good description, based on specimens that Willey had collected in the 1890s in New Guinea etc. as a parasite on the pearly nautilus. Willey had mentioned these in a letter to his prof Lankester in:
Willey, A. (1896) Letters from New Guinea on Nautilus and some other Organisms. Quarterly Journal of Microscopical Science, new series, 39:145-180.
Stebbing quotes the passage of interest wherein Willey mentions "Caligus nautili" [as a nomen nudum]. Stebbing gives Willey credit for the species Anchicaligus nautili, as do you. However, it should be Anchicaligus nautili Stebbing, 1900. That is, both the genus and the species are Stebbing's.