''Placostylus ambagiosus'' is a species of

flax snail ''Placostylus'', or flax snails, are a genus of very large, air-breathing land snails, terrestrial pulmonate gastropod molluscs in the family Bothriembryontidae.MolluscaBase eds. (2020). MolluscaBase. Placostylus H. Beck, 1837. Accessed through: ...

( Māori: pūpū whakarongotaua), a large air-breathing

land snail A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. ''Land snail'' is the common name for terrestrial gastropod mollusks that have shells (those without shells are known as ...

, a terrestrial

pulmonate Pulmonata or pulmonates, is an informal group (previously an order, and before that a subclass) of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. The group includ ...

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

in the family

Bothriembryontidae Bothriembryontidae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Orthalicoidea. Taxonomy This family has been named Placostylidae and had no subfamilies (according to the taxonomy of th ...

Description

This snail has a large ( long) shell, which is heavily calcified. The size of the adult shell is habitat dependent, but the shell shape is not plastic. ''Placostylus ambagiosus'' is highly valued by Te Aupōuri me Ngāti Kurī (the indigenous people of northern New Zealand) as a food source, musical instrument and in the past this snail provided alarm calls at night warning of approaching invaders.

Distribution

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 the past local Māori moved and propagated populations of ''Placostylus ambagiosus,'' so today at least three extant populations are found on old

pā The word pā (; often spelled pa in English) can refer to any Māori village or defensive settlement, but often refers to hillforts – fortified settlements with palisades and defensive terraces – and also to fortified villages. Pā sites o ...

sites (fortified settlements), along with other species that were cultivated such as karaka ( ''Corynocarpus laevigatus'') and harakeke ('' Phormium tenax'').

Biology

This snail feeds at night on fallen leaves on the forest floor. A favorite plant species is hangehange (''Geniostoma ligustrifolium''). ''Placostylus ambagiosus'' needs year round moisture provided by deep leaf-litter. Eggs are laid in clutches (average 43 eggs) in the shallow hollows in the soil. The species is slow-growing with a lifespan of 10–22 years and strong site fidelity The same individual snail has been found under the same food plant for 12 years. The species is endangered due to predation from rats and birds, habitat damage by pigs and horses and competition from introduced snails.

Hypothetical subspecies

Based on molecular phylogeny (mtDNA) and shell morphology research it was suggested in 2011 by Buckley et al. that there are no subspecies of ''Placostylus ambagiosus''.Buckley 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 Zoology'' 38(1): 55-81. . However, in the past, what were thought to be eight extant

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

and a number of undescribed but distinct populations, were named; six of these "subspecies" are now

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

(marked with a †); conservation statuses were given according to the

New Zealand Threat Classification System The New Zealand Threat Classification System is used by the Department of Conservation to assess conservation priorities of species in New Zealand. The system was developed because the IUCN Red List, a similar conservation status system, had some ...

for the extant taxa: "nationally critical" and "nationally endangered": At least five subspecies of ''Placostylus ambagiosus'' can be recognized using shell shape (not size or location) of individuals snails suggesting these represented distinct populations that require protection. *''Placostylus ambagiosus'' "Herangi Hill" † *''Placostylus ambagiosus'' "nouvelle" - nationally endangered *''Placostylus ambagiosus'' "Haupatoto" - nationally critical *''Placostylus ambagiosus'' "Kauaetewhakapeke Stream" - nationally critical *''Placostylus ambagiosus'' "Kohuronaki" - nationally critical *''Placostylus ambagiosus'' "Poroiki" - nationally critical *''Placostylus ambagiosus'' "Te Paki" - nationally endangered *''Placostylus ambagiosus'' "Tirikawa" - nationally critical *''Placostylus ambagiosus ambagiosus'' Suter, 1906 - nationally critical *''Placostylus ambagiosus annectens'' Powell, 1938 2 *''Placostylus ambagiosus consobrinus'' Powell, 1938 - nationally critical *''Placostylus ambagiosus gardneri'' † *''Placostylus ambagiosus hancoxi'' 1 *''Placostylus ambagiosus hinemoa'' † *''Placostylus ambagiosus keenorum'' Powell, 1938 - nationally endangered *''Placostylus ambagiosus lesleyae'' † *''Placostylus ambagiosus michiei'' Powell, 1951 - nationally endangered *''Placostylus ambagiosus pandora'' Powell, 1951 - nationally critical *''Placostylus ambagiosus paraspiritus'' Powell, 1951 - nationally endangered *''Placostylus ambagiosus priscus'' † *''Placostylus ambagiosus spiritus'' † *''Placostylus ambagiosus watti'' Powell, 1947 - nationally critical *''Placostylus ambagiosus whareana'' Powell, 1951 - nationally critical *''Placostylus ambagiosus worthyi'' †

Description

Distribution

Biology

Hypothetical subspecies

References

Further reading