Rhynchospio aciliata sp. nov. A–C paratype (NIBRIV0000893852) D, E paratype (NIBRIV0000893851) fixed in formalin, with a solution of methyl green in distilled water A dorsal view of anterior end, nuchal organs (arrowheads) B lateral view of chaetigers 19–23, intersegmental lateral pouches (arrowheads) C lateral view of chaetigers 66–69, oocytes (arrowheads) D lateral view of whole body, at least one week after staining E ventral view of chaetigers 25–30. Scale bars: 0.5 mm (A); 0.2 mm (B, C, E); 2 mm (D).