A number of subspecies were recognised; Placostylus bollonsi arbutus and P. b. bollonsi are classified by the New Zealand Department of Conservation as being Nationally Endangered, while Placostylus bollonsi caperatus is classified as Nationally Critical.[3]
^ abBuckley T. R., Stringer I., Gleeson D., Howitt R., Attanayake D., Parrish R., Sherley G. & Rohan M. (2011). "A revision of the New Zealand Placostylus land snails using mitochondrial DNA and shell morphometric analyses, with implications for conservation". New Zealand Journal of Zoology38(1): 55-81. doi:10.1080/03014223.2010.527997.
Further reading
Suter, H. (1908). A new Placostylus from New Zealand. Transactions of the New Zealand Institute, 40: 340-343, pl. 25.