From Sikorski et al (2018: 962): "anterolateral corners of the prostomium fused to peristomium generally only by an inconspicuous (in dorsal view) membrane (membrane connecting the prostomium could be hidden in the groove between the two); nuchal organ generally quite short (~10 anterior chaetigers long) and not so variable; other numerical characters highly variable and by notopodial hooded hooks which may present in the very posterior chaetigers."
Sikorski, Andrey; Gunton, Laetitia M.; Pavlova, Lyudmila. (2017). Laonice species (Polychaeta, Spionidae) from the Whittard Canyon (NE Atlantic) with descriptions of two new species. Journal of the Marine Biological Association of the United Kingdom. 97(05): 961-973.