- Ceuthophilus zonarius Walker, 1869: 203.
Holotype; female; NHMUK015982273; deposited at: Natural History Museum, London (NHMUK); Canada: British Columbia: Vancouver Island
- Ceuthophilus agassizii (Scudder, 1861) in Scudder, 1869: 21.
- Ceuthophilus agassizii (Scudder, 1861) in Brunner von Wattenwyl, 1888: 309.
- Ceuthophilus crassus Scudder, 1894: 85.
Syntype; male; 3e140b4e-717c-46cd-9c0c-d083cc2a64b8; deposited at: Academy of Natural Sciences of Philadelphia (ANSP); unknown [probably British Columbia or Washington State]
- Ceuthophilus agassizii (Scudder, 1861) in Scudder, 1894: 81.
- Ceuthophilus agassizii (Scudder, 1861) in Scudder, 1899: 118.
- Ceuthophilus crassus Scudder, 1894 in Kirby, 1906: 134.
- Ceuthophilus agassizii (Scudder, 1861) in Kirby, 1906: 133.
- Ceuthophilus crassus Scudder, 1894 in Rehn & Hebard, 1912: 71.
- Ceuthophilus agassizii (Scudder, 1861) in Karny, 1928: 312.
- Ceuthophilus agassizii (Scudder, 1861) in Karny, 1930: 195.
- Ceuthophilus crassus Scudder, 1894 (subjective synonym of Raphidophora [sic] agassizii Scudder, 1861) in Hubbell, 1936: 130.
- Ceuthophilus zonarius Walker, 1869 (subjective synonym of Raphidophora [sic] agassizii Scudder, 1861) in Hubbell, 1936: 130.
- Ceuthophilus (Ceuthophilus) agassizii (Scudder, 1861) in Hubbell, 1936: 130.
- Ceuthophilus crassus Scudder, 1894 (subjective synonym of Raphidophora [sic] agassizii Scudder, 1861) in Karny, 1937: 271.
- Ceuthophilus zonarius Walker, 1869 (subjective synonym of Raphidophora [sic] agassizii Scudder, 1861) in Karny, 1937: 271.
- Ceuthophilus crassus Scudder, 1894 (subjective synonym of Raphidophora [sic] agassizii Scudder, 1861) in Vickery & Kevan, 1986: 144.