Several other species and subspecies were at times placed in Plutonides but have subsequently been moved to other genera.

In terms of the Scandinavian Middle Cambrian sequence the genus ranges from the Baltoparadoxides oelandicus Biosuperzone (B. pinus Biosubzone) at the type locality for P. sedwickii on Trwyncynddeiriog headland located 1.3 km (0.81 mi) south-southwest of St David’s Cathedral and 500 m (1,600 ft) east of Porth Clais Harbour - Pen-y-Cyfrwy Member, Newgale Formation,[1] and possibly to middle part of the Mawddachites hicksii Biozone on the Penpleidiau (eastern) Headland of Caerfai Bay south of St David’s in southwest Wales, where P?

sedgwickii, described by Smith and White (1963) from the Baltoparadoxides pinus Biosubzone in the upper part of the Purley Shale Formation of Warwickshire, central England[7] was redescribed by Rushton (1966, p. 42, pl.

Vanĕk et al. (1999) [9] described cranidia from the Middle Cambrian of Skrije - Týřovice area in the Czech Republic as Plutonides hicksi, although the specimens illustrated are of a different species to that from Wales.

Fletcher (2007) however, has also since established the new subgenus, Paradoxides (Mawddachites), to include P. hicksii as type species.