However, in 1961, the American paleontologist Erik Norman Kjellesvig-Waering split Hughmilleria in two subgenera, H. (Hughmilleria) for species with large ovoid marginal eyes and H. (Nanahughmilleria) for small reniform intramarginal (within the margin) eyes. Since H. patteni fulfilled this condition, it was referred to H. (Nanahughmilleria). It was not until 2008 when during a phylogenetic review of the entire Adelophthalmidae family by the Norwegian Odd Erik Tetlie and German Markus Poschmann paleontologists, N. patteni was recognized as sufficiently different to represent its own genus due to the anterior position of its eyes, much more exaggerated than in the other adelophthalmid genera. The first part of the generic name is composed of the word Eysysla, the Viking name for Saaremaa, and the second part by opterus, a suffix commonly used in eurypterids which means "wing" (and therefore, translated as "wing of Eysysla").
