According to article 68.2.1. of the ICZN, "The expressions "gen. n., sp. n.", "new genus and species", or an equivalent, applied before 1931 to only one of two or more new nominal species originally included in a new nominal genus or subgenus, are deemed to be an original designation if no other type species was explicitly designated." This way, Lycastoides alticola Johnson, 1903 is the type of the genus Lycastoides by original designation.
Johnson, Herbert Parlin 1903. Fresh-water nereids from the Pacific coast and Hawaii, with remarks on fresh-water Polychaeta in general. 205-222. In. Mark Anniversary Volume. To Edward Laurens Mark, Hersey professor of anatomy and director of the zoölogical laboratory at Harvard university, in celebration of twenty-five years of successful work for the advancement of zoölogy from his former students, 1877-1902. Henry Holt & Co. New York. available online athttp://www.biodiversitylibrary.org/page/1324600