original description
Cook, O. F.; Collins, G. N. (1895). The Craspedosomatidae of North America. Annals of the New York Academy of Sciences, 9: 1-100. New York, available online at http://biodiversitylibrary.org/page/35260543
page(s): 6 [details]
additional source
Shelley, R. M.; Smith, J. M. (2016). Parajulid milliped studies XII: Initial assessment of Ptyoiulus Cook 1895 and neotype designations for Julus impressus Say 1821 and J. montanus Cope 1869 (Diplopoda: Julida). Insecta Mundi. (0522): 1-21., available online at https://digitalcommons.unl.edu/insectamundi/1027/ [details] Available for editors 
From editor or global species database