''Diloma zelandicum'' is a species of

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

, a

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

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 Trochidae, the top snails or top shells.Bouchet, P. (2010). Diloma zelandicum(Quoy & Gaimard, 1834). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=546852 on 2011-07-03

Description

The height of the shell attains 20 mm, its diameter 25 mm. The imperforate shell is depressed and has an orbiculate-conoidal shape. The six

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane floral ...

s are separated by impressed sutures. The whorls are slightly convex, greenish-black and shining. They are spirally sulcate, the sulci about 5 on the penultimate whorl. The

body whorl The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk. In gastropods In gastropods, the b ...

is much dilated, slightly depressed above, rounded in the middle, very obliquely striate, obsoletely transversely sulcate, slightly convex beneath. The aperture is subrhomboidal and lirate within. The acute lip is green. The basal margin is thickened within. The white columella is compressed and arcuate. The columellar callus is broadly expanded, subdepressed at the place of the umbilicus.Tryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia
(described as ''Monodonta atrovirens'')

Distribution

This marine species is endemic to New Zealand and occurs off North Island, South Island and

Stewart Island Stewart Island ( mi, Rakiura, ' glowing skies', officially Stewart Island / Rakiura) is New Zealand's third-largest island, located south of the South Island, across the Foveaux Strait. It is a roughly triangular island with a total land ar ...

. It has also been reported from Tasmania.

References

* Powell A. W. B., ''New Zealand Mollusca'', William Collins Publishers Ltd, Auckland, New Zealand 1979 * Spencer H.G., Marshall B.A. & Waters J.M. (2009) ''Systematics and phylogeny of a new cryptic species of Diloma Philippi (Mollusca: Gastropoda: Trochidae) from a novel habitat, the bull kelp holdfast communities of southern New Zealand''. Invertebrate Systematics 23: 19–25.

External links

* {{Taxonbar, from=Q5277025 zelandicum Gastropods of New Zealand Gastropods described in 1834