- Phormosoma luculentum Koehler, 1896, non A. Agassiz, 18?? accepted as Hygrosoma petersii (A. Agassiz, 1880)
- Phormosoma petersii A. Agassiz, 1880 accepted as Hygrosoma petersii (A. Agassiz, 1880)
- Phormosoma placenta Thomson, 1872
- Phormosoma placenta sigsbei A. Agassiz, 1880
- Phormosoma uranus Koehler, 1898, non Thomson, 1877 accepted as Hygrosoma petersii (A. Agassiz, 1880)
- Phormosoma uranus Thomson, 1877 accepted as Tromikosoma uranus (Thomson, 1877)