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Olives and ancillids

The family Olividae consists of two subfamilies.  The species of the Olivinae are the glossy, attractive shells well known to collectors and treated in a number of monographs.  These are primarily inhabitants of tropical seas, and only a few species are found very rarely in northern  NSW.  The other subfamily, the Ancillinae, has species which are smaller, and most occur only subtidally, so are less well known and less collected.  Of this subfamily, seven species occur in NSW, all endemic to Australia .  They all live subtidally, but two species occur fairly commonly washed up on beaches.

Ancillids are sand dwelling carnivores and scavengers.  The animal has a large flat foot that may extend twice the length of the shell, completely covering the shell.  In some species the foot provides a limited swimming capability, probably used to escape predators.  The construction of the shells is unusual in that a glaze or callus is applied over the spire, usually obscuring the suture on the spire, and forming a spiral band below the suture on the body whorl.

The tropical olive shells have received much taxonomic attention, but there is no overall review of the ancillids.  The Australian ancillids are in urgent need of revision, as many have been named from specimens available in one state, without investigating the variation throughout the range from Queensland to Western Australia .

Family References: 

• Kilburn, R.N. 1981. Revision of the genus Ancilla Lamarck, 1799.  Annals Natal Museum 24 (2):349-463

• Ninomiya, T. 1991. Sixteen new species of the Ancillinae (Gastropoda: Olividae) from Australia .  Venus  49(2): 69-82.

• Tursch, B. & Greifeneder, D. 2001. The genus Oliva and the species problem. Ancona : L’Informatore Piceno

Coverage:  All NSW members of the family are figured, with the exception of the following species.

• Tropical Indo-West Pacific species that occur rarely in northern NSW:

Oliva annulata (Gmelin, 1791)  Indo-West Pacific, to Solitary Islands,  NSW. 

Oliva oliva (Linnaeus, 1758).  Indo-West Pacific, to Wooli, NSW.

Oliva miniacea Röding, 1798.  Indo-West Pacific to Coffs Harbour, NSW

• Amalda fasciata  Ninomiya, 1991. Known only from the holotype (type locality "Off Clarence River, NSW", 6.3 mm length) that is a broken, worn specimen that makes recognition of the species difficult.

• Amalda nitidanosum Ninomiya, 1991.  Known only from the holotype (holotype locality "Off Jervis Bay, NSW, 400-1000 m", length 10.8 mm) and paratype , both worn, broken specimens that make recognition of the species difficult.

Identification Notes: In ancillids the spire is covered with a glaze (also referred to as ‘callus’ if it is thick) applied after the creation of the normal spiral shell.  There may be two layers of callus, applied at different times, over different parts of the shell.  The callus on the spire may be smooth or spirally ribbed.  The subsutural callus is a spiral band of callus below the suture.  Below the centre of the body whorl there is a groove known as the ancillid groove, which may be weak or strong. Below the ancillid groove is the ancillid band, and below that the anterior fasciole, or fasciolar band.  The fasciolar band usually has a ridge in the centre, which again may be weak or strong.  The columellar pillar may be smooth or with plaits, varying in number and strength.