Phascolion (Isomya) tuberculosum Théel

Cutler, Edward B., Schulze, Anja & Dean, Harlan K., 2004, Zealand species, Zootaxa 525, pp. 1-19 : 11

Phascolion (Isomya) tuberculosum Théel

Phascolion tuberculosum Théel, 1875: 15 –16.

Type locality: Koster, western Sweden, 25– 35 m.

Remarks: The single 25 mm representative of this species had been living in a gastropod shell and has a cluster of epizoans around the base of the introvert. The holdfast papillae are flattened discs some with a circular margin of pale hardened protein. There are sparsely scattered dark, large hooks. The two retractor muscles are of almost equal size and both originate very close to the posterior end of the trunk.

Distribution: Common in the northeastern Atlantic, including the Azores, Mid­Atlantic Ridge, Bay of Biscay, and Scandinavian waters at bathyal depths (25–2700 m). The few specimens from Japan and New Zealand (as P. temporariae, Edmonds, 1976 ) from 93–300 m point to a low­density population in the western Pacific Ocean.

This sample reinforces that previous report from New Zealand of what appears to be a low­density southern hemisphere population.