From Sikorski et al. (2018: 962): "Can easily be distinguished by a prostomium clearly fused with peristomium by anterior margin; capillaries in anterior part of body arranged in two vertical rows and all numerical characters quite variable."
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.