Although superficially similar to the related genus Parahughmilleria, Pruemopterus can be distinguished from other adelophthalmids by several features, most notably its wide and vaguely rectangular carapace (head plate) and its rounded, rather than elongated, eyes.

The fossil deposits the specimen was uncovered in belong to the Klerf Formation and are of Early Devonian age, specifically the uppermost Lower Emsian epoch.

[1] The fossil was not formally described by Poschmann until 2020, when he determined that the combination of traits displayed suggested that it was an adelophthalmid eurypterid similar to Parahughmilleria, known from the same deposits, but differing in features of its carapace, opisthosoma and telson.

The specimen is today housed at the Generaldirektion Kulturelles Erbe, Direktion Landesarchäologie/Erdgeschichte in Koblenz, Germany, and is part of the State Collection of Natural History of Rhineland-Palatinate.

The short and rectangular carapace of Pruemopterus, and its eyes being rounded rather than elongated, easily distinguishes the genus from the adelophthalmid genera Eysyslopterus, Pittsfordipterus, Bassipterus, Nanahughmilleria and Adelophthalmus.

Pruemopterus can be distinguished from Parahughmilleria hefteri by several features, including its more centrally positioned and rounder eyes, its wider carapace, the epimera being much more prominent, and the telson being broader and more robust.

[1] Poschmann also noted in his description of the type specimen that there were also close similarities to the Hughmilleriidae in the Pterygotioidea superfamily, though Pruemopterus differed from the genera in that family in having prominent lateral epimera on its opisthosomal segments (a feature for the most part missing among the hughmilleriids) and its eyes not being placed on the margin of the carapace.

The Early Devonian eurypterid-yielding fossil sites in the Rhineland have been interpreted as having been part of a shallow aquatic environment with brackish to fresh water,[3] such as an estuary or a bay.