The three subspecies of P. granulosus, P. g. laepensis, P. g. salawinensis and P. g. maepoensis are from the Late Devonian of Thailand.[2]
^Conodonts across the Devonian/Carboniferous boundary in SE Sardinia (Italy). Angelo Mossoni, Nicola Carta, Carlo Corradini and Claudia Spalletta, Bulletin of Geosciences, 2015, volume 90, issue 2, pages 371–388, doi:10.3140/bull.geosci.1524
^Late Devonian conodonts from northwestern Thailand. Norman M. Savage (2013), Bourland Printing / Trinity Press. pages 1–48, ISBN978-0-578-11919-9.