Kjellesvig-Waering named the species "P. bolivianus" in 1964 based on fossils recovered from deposits of Emsian-Eifelian (Early to Middle Devonian) age in Bolivia. This species was the first pterygotid to be discovered in South America, the first Devonian pterygotid to be recovered in deposits in the Southern Hemisphere and also represents one of the last known living member of the pterygotid family. The specimen (PE6173, housed at the Chicago Natural History Museum) includes the well-preserved anterior half of a chelicera and ramus. The tooth of the ramus are short, wide and conical, all being slightly curved backwards. The terminal tooth is larger, but only slightly, than the tooth succeeding it and the inwards bend of the claw suggests that another tooth might be present, creating a kind of "double tooth combination" that is also present in some other species, such as "P. lightbodyi", "P. impacatus" and "Erettopterus brodiei". The total length of the fossilized ramus is 2.35 cm (1 in), but it likely only represents around half of the full ramus. As in other species (and the Pterygotidae in general), the teeth are finely ribbed. It can be distinguished from all other species of "Pterygotus" by the wide but short and evenly sized teeth as well as the terminal tooth not having any particular development. In 2019, a new fragmentary ramus of a chelicera was found in the Cuche Formation of Colombia. The specimen (SGC-MGJRG.2018.I.5), assigned with uncertainty to "P. bolivianus" due to similarities with its holotype, represents the first eurypterid of Colombia and the fourth of South America. The fossil was dated as Frasnian (Late Devonian), showing that "Pterygotus" did not become extinct during the Middle Devonian as previously thought.