Xenosiphon branchiatus (Fischer, 1895):

3, pl. 1, figs 1–1a, 2, as Sipunculus mundanus var. branchiatus; type locality: Esmeraldas, Ecuador. — Fisher 1947: 360–363, as Xenosiphon branchiatum (from La Paz, Baja California Sur to Panama). — Fisher 1952: 377–380, pl. 19, as X. branchiatum (La Paz, Baja California Sur; Panama, Hassler Expedition). — Brusca 1980: 125, as X. branchiatum (Gulf of California). — Cutler et al. 1992: 154 (Curú Beach, Gulf of Nicoya; Tamarindo Beach, Costa Rica, in fine sand). — Dean 2001: 86 (Conchal Beach, Brasilito Bay; Curú Beach, Gulf of Nicoya; Tamarindo Beach, Tamarindo Bay, Costa Rica, in fine sand). — Schulze et al. 2007: 186 (Tamarindo Beach, Costa Rica).