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Family  Philinidae

Philinids

 

 

 

Philinids are large-bodied, lozenge-shaped head-shield slugs that completely enclose a thin, fragile, internal shell in the rear half of the body beneath the posterior shield. The shell has a broad aperture and a low spire, or no spire at all. The family occurs worldwide in shallow and deep water on soft substrates; shells range in size from 2 to 40 mm in length.

Most philinids live infaunally in fine sandy or muddy habitats, but a few are epifaunal. The most common and by far the largest NSW species, Philine angasi, lives intertidally and subtidally burrowing in fine silty sand. The infaunal animals are usually white while the epifaunal species may be brightly coloured.

The diet of philinids is frequently small bivalves. The animal has a radula as well as three hard gastral plates in the stomach, used for crushing and grinding the food.

In NSW three species are recorded. As well as the large, common Philine angasi there are two much smaller species, one with a shell of only 2 mm long, the other twice that size. One of these occurs intertidally and in the shallow subtidal, but the other is known from dredgings from 15-200 m.

Family Reference

Burn (2015) figured the most common species in Victoria. Rudman (1972) reported in detail on the anatomy of the genus.

Coverage

As well as the three species detailed here, there are three other species of the family recorded from NSW in old records:

Philine burrowsi Burn, 1961 is based on a single live animal specimen of which the shell was destroyed beyond reconstruction but it is completely smooth. The preserved animal measures 15 mm long. Its radular teeth and gizzard plates are different to those of P. angasi.

Philine columnaria Hedley & May, 1908 is of doubtful occurrence in NSW.

Philine oscitans Hedley, 1907 is known only from the holotype and another lot, but they may belong to different species.

The following additional species was reported as observed in northern NSW by Nimbs & Smith, 2017:

Philine orca Gosliner, 1988. Tweed Heads and Solitary Islands.

Identification Notes

Shells are thin and fragile, with the aperture occupying at least three-quarters of the ventral surface.

 


Copyright Des Beechey 2018