Key to Geographical Ranges
The symbols K.A.C.F.M.An. are used to indicate the geographical range of the species. They have been adopted to give an approxomation of the range of each species within New Zealand.
Kermadec Islands
Aupourian - Kaipara Harbour, north around North Cape, encompassing the Three Kings Islands and south to East Cape
Cookian - Lower North Island and the northern part of the South Island
Forsterian - Otago, Fiordland and Stewart Island
Moriorian - Chatham Islands, Pitt Island
Antipodean - Subantarctic Islands of New Zealand
Fw =
L =
N =
North Island
S =
South Island
E =
I =
R =
Sf =
Fo =

Glossary of terms used in describing Mollusca

  • Acicular Needle shaped.
  • Adductor Muscles Anterior and posterior muscles that close a bivalve shell.
  • Amphitropical Species that have disjunct distribution patterns, one part of the range being to the north of the Equator, the other to the south, the different parts being geographically quite separate.
  • Anterior Apertural or head end of a gasropod
  • Anterior canal Notch or tubular extension of anterior apertural margin supporting the inhalant siphon.
  • Aperture: Opening of the shell providing outlet for the head and foot. Entrance of the body whorl.
  • Axial Longitudial ribs or colour bands. Parallel to the shells axis.
  • Axis Imaginary line through the apex, about which the whorls are coiled. Central structure of a Gastropod shell.
  • Benthic Bottom dwelling.
  • Benthopelagic Both benthic and pelagic.
  • Bivalve Belonging to the Molluscan class Bivalvia. Usually having a shell composed of two valves, hinged together. Includes clams, oysters, scallops.
  • Body Whorl Last whorl of a univalve/gastropod.
  • Byssus Fibres secreted by foot in bivalves, used for attachment.
  • Canaliculate Gutter-like or channelled. Applied to suture of some Gastropod shells.
  • Cardinal In bivalves, situated more or less in the central part of the hinge area directly below the beaks.
  • Carinate Angled or keeled.
  • Cerata Dorsal appendages in nudibranchs.
  • Chondrophore Pit containing the resilium, a chitinous pad in certain bivalves.
  • Clathrate Latticed by axial and spiral ridges.
  • Columella Apertural part of axis in a spiral gastropod.
  • Concentric Arc-like ridges or striae following the same direction as the ventral margin of a bivalve shell or the growth lines.
  • Dentate Sculptured with teeth or short ridges.
  • Dextral Right hand coiled Gastropod.
  • Divaricate Forked or branched. Diverging sculptural elements, often forming chevrons.
  • Dorsal In gastropods, the side of the shell opposite the aperture. In bivalves, the surface or margin nearest the hinge.
  • Dorsum Back of the shell, opposite the aperture in Gastropods.
  • Escutcheon Depressed area behind ligament in bivalves.
  • Fasciole In Gastropods, either a spiral ridge at base of pillar, or groove on shoulder area, often ending in a sinus.
  • Fimbriate Fringed.
  • Foramen A natural hole or perforation.
  • Fusiform Spindle shaped, Gastropods with tall spire and long canal.
  • Gastropod Belonging to the large Molluscan class Gastropoda, often but not always having a single shell. Includes snails, slugs, whelks.
  • Hinge Junction of two bivalve shells, usually characterised by interlocking teeth.
  • Holotype A single specimen upon which a species is based.
  • Imperforate Without an umbilicus.
  • Labrum Outer lip in Gastropods.
  • Lamellae Thin plates or sharply raised ridges.
  • Lectotype A lectotype is a specimen later selected to serve as the single type specimen for species originally described from a set of syntypes. In zoology, a lectotype is a kind of name-bearing type. When a species was originally described on the basis of a name-bearing type consisting of multiple specimens, one of those may be designated as the lectotype. Having a single name-bearing type reduces the potential for confusion, especially considering that it is not uncommon for a series of syntypes to contain specimens of more than one species.
  • Lirate Fine raised lines.
  • Lirations Fine raised lines.
  • Lunule Heart shaped depression in front of beaks in bivalves.
  • Mantle Outer edge of molluscan animal that secretes shell.
  • Mesopelagic Inhabiting the intermediate depths of the sea, between about 200 and 1,000 metres.
  • Neotype A specimen later selected to serve as the single type specimen when an original holotype has been lost or destroyed or where the original author never cited a specimen.
  • Nepionic Stage following the embryonic one.
  • Nodose Bearing tubercules or knobs.
  • Operculum In Gastropods
  • Pallial Sinus An indentation or inward bending in the pallial line on the interior of a bivalves valves. Corresponds to the position of the siphons.
  • Paralectotype Any additional specimen from among a set of syntypes, after a lectotype has been designated from among them.
  • Paratype Specimen or specimens from the same lot as the holotype, used in original description of species.
  • Parietal Upper part of inside wall of aperture in Gastropods.
  • Pelagic Swimming or drifting in the open sea.
  • Periostracum Outermost horny covering of a shell
  • Peristome Aperture margin of Gastropod.
  • Plaits Fold on columella or pillar of Gastropods.
  • Prodissoconch Embryonic shell in Bivalves, often preserved at beaks.
  • Protoconch Embryonic shell in Gastropods, often preserved at apex.
  • Pyriform Pear-shaped.
  • Resilium Chitinous pad associated with Bivalve hinge. Causes the shell to open when adductor muscle relaxes.
  • Reticulated Cross ridged, forming network pattern.
  • Rhinophores Pair of club like sensory appendages in nudibranchs.
  • Scalariform Loosely coiled, unwound.
  • Selenizone Spiral band of crescentic growth lines, associated with marginal slit or foramen, in certain univalves.
  • Sinistral Left hand coiled Gastropod, opposite of dextral.
  • Sinus A curve, cleft or indentation.
  • Spatula Spoon-shaped central area of the shell interior of a limpet, usually differing in colour from the rest of interior of the shell. Usually resulting from where the animal was attached to the shell.
  • Spinose Bearing many spines.
  • Spire In Gastropods: all whorls except last one (body whorl).
  • Syntype A syntype is any one of two or more specimens that is listed in a species description where no holotype was designated
  • Teleoconch Entire shell, other than protoconch.
  • Tessellated Checkered pattern, mosaic-like squares.
  • Topotype A biological specimen that is of the same species or subspecies as a type specimen and has been collected from the same location.
  • Umbilicus Gap between reflected inner lip of shell aperture and the first body whorl of Gastropod.
  • Umbo Early part of bivalve shell, often called the beak. Larval shell.
  • Varix A ridge formed at the outer lip in some Gastropods. Left at successive growth stages in some species, and dissolved prior to new growth in other species.
  • Whorl One complete spiral of a Gastropod shell.