In an article by Geyer and Peel (Reference Geyer and Peel2017, p. 288), we inadvertently coined a species-group name, Elrathia groenlandica Geyer and Peel, Reference Geyer and Peel2017 for a trilobite species of the superfamily Ptychopariacea. This name is a junior homonym of Elrathia? groenlandica Poulsen, Reference Poulsen1927 and is thus invalid (ICZN Article 57.2; see International Commission on Zoological Nomenclature, 1999). We therefore propose Elrathia hensonensis new name as the replacement name for E. groenlandica Geyer and Peel, Reference Geyer and Peel2017. The new species name is derived from the Henson Gletscher area, North Greenland, the region where the type locality of this species is located.

Elrathia? groenlandica Poulsen, Reference Poulsen1927 was introduced for a trilobite species from boulders in the Miaolingian Cape Wood Formation at Cape Frederik VII, Inglefield Land, assigned to the Glossopleura Zone (Poulsen, Reference Poulsen1927, p. 274, pl. 17, fig. 7). This species is based on a single, nearly complete cranidium of only 4 mm length, figured in small size in the original publication and subsequently neglected except for a mention by Poulsen (Reference Poulsen1964).

Poulsen (Reference Poulsen1964) regarded Elrathia? groenlandica as a synonym of Ptychoparella brevicauda Poulsen, Reference Poulsen1927, which occurs more or less in the same strata, but neither described nor illustrated any material. The problems of the generic concept of Ptychoparella Poulsen, Reference Poulsen1927 were discussed in some detail by Geyer and Peel (Reference Geyer and Peel2017). Without precise knowledge on the morphology of the thorax and pygidium as well as the morphologic plasticity, no confident generic assignment is possible at this moment.