SEM image of specimens of Rhadinorhynchus oligospinosus from Scomber japonicus and Trachurus murphyi from off the Pacific coast of Peru. (A) A profile of the anterior part of a male specimen showing the neck and proboscis curvature and the distribution of trunk spines. (B) The proboscis and curved neck of another specimen. (C) The anterior end of a proboscis showing the minute size of the apical hooks compared to subapical hooks. (D) A typical hook at mid-proboscis showing its curvature and its thickness at base. (E) A gallium cut section of a proboscis hook showing its thick cortical layer and partially vacuolated center. (F) A basal view of a trunk spine showing its broad base.