Aspidosiphon (Akrikos) mexicanus (Murina, 1967)  

This species does not have the typical aspidosiphonid appearance. The introvert arises in an atypical angle and it is up to 5 times the trunk length. The anal shield is almost nonexistent, and caudal shield is completely absent. The hooks are small, compressed unidentate, and scattered on the distal part of the introvert. Aspidosiphon mexicanus has been reported only in the Atlantic in sandy and muddy sediments in depths over 80 and up to 320 m.