T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Slug (Paua Slug) Schizoglossa novoseelandica novoseelandica

Kingdom:  Animalia
Phylum:  Mollusca
Class:  Gastropoda
Unranked:  Heterobranchia
Clade:  Euthyneura
Clade:  Panpulmonata
Clade:  Eupulmonata
Clade: Stylommatophora
Informal group:  Sigmurethra
Superfamily:  Rhytidoidea
Family:  Rhytididae
Genus:  Schizoglossa
Species:  S. novoseelandica
Sub Species: S. novoseelandica novoseelandica
Binomial name:  Schizoglossa novoseelandica novoseelandica
Synonym: Daudebardia novoseelandica
Common name:  Paua Slug

Schizoglossa novoseelandica novoseelandica is a large, native, predatory carnivorous species of air-breathing land slug or semi-slug, a terrestrial gastropod mollusc in the family Rhytididae. It is the type species of the genus Schizoglossa and is found only in New Zealand only in the upper half of the N. Island. Localities include: Te Henui Walkway New Plymouth, Kakepuku Mountain in Waikato Region, Piropiro in the Pureora Forest Park, Wainuiomata in Wellington Region, Toko near Stratford and Cape Egmont and Mount Messenger Conservation Area in Taranaki Region, Wanganui (in Bushy Park) and Hunterville in Manawatu-Wanganui Region, Whangarei Heads in Northland Region, Ohingaiti, Kaimai Ranges between Waikato Region and Bay of Plenty Region. It can be also found in Mount Tongariro/Lake Taupo area. The other subspecies is Schizoglossa novoseelandica barrierensis and is only found on Great Barrier Island in the Hauraki Gulf.

The paua slugs (genus: Schizoglossa) exhibits a small, vestigial, external paua-shaped shell, hence its common name. Most other species of slugs retain a remnant of their shell, which is usually internalised. 

This is a slug with an external vestigial shell that is small, rudimentary, auriform (ear-shaped) and is situated far back on the animal. The shell is incapable of containing the body and is reduced to the function of a shield for the lungs and heart. It also serves as storage for calcium salts. The shell is rudimentary, paucispiral (having few spirals), and nacreous (resembling mother of pearl) within. The columella ((meaning little column) is excavated into a pit for the reception of the shell-muscle. The animal has no rachidian (2 pairs of lateral teeth) teeth. Like other slugs and snails, they prefer a damp, protected environment, foraging nocturnally when the humidity is high.

Though the survival of this species is not threatened it under pressure due to habitat destruction and by the foraging of introduced predators like the rat, stoat, weasel, pig and blackbirds. 

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The five photos below are of a slug photographed in the Te Henui Walkway, New Plymouth.  

The slug in resting position.

Close up of Schizoglossa novoseelandica novoseelandica head.

The paua (abalone like) vestigial shell.

Most slugs retain a remnant of their shell, which is usually internalised but the New Zealand Paua slugs have a remnant of an exterior shell.
Photos of an 18 mm long empty shell.

The photos below are of a slug found on a farm at Putts Rd. Uriti (July)

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/