| Synonym | Author | CoL Status | Valid | Synonymy | Combination |
|---|---|---|---|---|---|
| Sipunculus mundanus var. branchiatus | Fischer, 1895 | synonym | No | senior synonym |
original combination |
| ! Xenosiphon branchiatum | Fischer, 1895 | ambiguous synonym | No | other |
original combination |
| Xenosiphon branchiatus | (Fischer, 1895) | accepted name | Yes | senior synonym |
change in rank |
| Xenosiphon branchiatus branchiatus | (Fischer, 1895) | synonym | No | senior synonym |
new combination |
| Xenosiphon caribaeum | Fischer, 1954 | synonym | No | junior synonym |
original combination |
| Xenosiphon caribaeus | Fischer, 1954 | ambiguous synonym | No | other |
original combination |