Placostylus ambagiosus is a species of flax snail (Māori: pupuharakeke), a large air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the family Bothriembryontidae.
This snail has a large (60–95 millimetres or 2.4–3.7 inches long) shell, which is heavily calcified.
This land snail species occurs in New Zealand. It is restricted to a small fragmented area of Northland Region, including the Aupouri Peninsula and Motuopao Island.
In 2011, Buckley et al. established, based on molecular phylogeny research and shell morphology research, that there are in fact no subspecies of Placostylus ambagiosus. However, in the past, what were thought to be eight extant subspecies and a number of undescribed but distinct populations were named; 6 of these "subspecies" are now extinct (marked with a †); conservation statuses were given according to the New Zealand Threat Classification System for the extant taxa: "nationally critical" and "nationally endangered":
Placostylus ambagiosus "Herangi Hill" †Placostylus ambagiosus "nouvelle" - nationally endangeredPlacostylus ambagiosus "Haupatoto" - nationally criticalPlacostylus ambagiosus "Kauaetewhakapeke Stream" - nationally criticalPlacostylus ambagiosus "Kohuronaki" - nationally criticalPlacostylus ambagiosus "Poroiki" - nationally criticalPlacostylus ambagiosus "Te Paki" - nationally endangeredPlacostylus ambagiosus "Tirikawa" - nationally criticalPlacostylus ambagiosus ambagiosus Suter, 1906 - nationally criticalPlacostylus ambagiosus annectens Powell, 1938 2Placostylus ambagiosus consobrinus Powell, 1938 - nationally criticalPlacostylus ambagiosus gardneri †Placostylus ambagiosus hancoxi 1Placostylus ambagiosus hinemoa †Placostylus ambagiosus keenorum Powell, 1938 - nationally endangeredPlacostylus ambagiosus lesleyae †Placostylus ambagiosus michiei Powell, 1951 - nationally endangeredPlacostylus ambagiosus pandora Powell, 1951 - nationally criticalPlacostylus ambagiosus paraspiritus Powell, 1951 - nationally endangeredPlacostylus ambagiosus priscus †Placostylus ambagiosus spiritus †Placostylus ambagiosus watti Powell, 1947 - nationally criticalPlacostylus ambagiosus whareana Powell, 1951 - nationally criticalPlacostylus ambagiosus worthyi †
