Didymocylindrus fusiformis (Ishii 1935) Pozdnyakov 1966

are endoparasites of

• World Register of Marine Species: Thunnus alalunga (Bonnaterre 1788) (Albacore) (adult)
• World Register of Marine Species: Katsuwonus pelamis (Linnaeus 1758) (Skipjack tuna) (adult)
• World Register of Marine Species: Thunnus thynnus (Linnaeus 1758) (Northern bluefin tuna) (adult)
• World Register of Marine Species: Katsuwonus pelamis (Linnaeus 1758) (Skipjack tuna) (adult)
• World Register of Marine Species: Katsuwonus pelamis (Linnaeus 1758) (Skipjack tuna) (adult)

geographic distribution

• World Register of Marine Species: New Zealand Exclusive Economic Zone
• World Register of Marine Species: Japanese part of the North Pacific Ocean
• World Register of Marine Species: Brazilian Exclusive Economic Zone
• World Register of Marine Species: Japanese Exclusive Economic Zone
• World Register of Marine Species: Hawaii

trophic guild

• World Register of Marine Species: endoparasite
• World Register of Marine Species: endoparasite
• World Register of Marine Species: endoparasite
• World Register of Marine Species: endoparasite
• World Register of Marine Species: endoparasite