Phascolion (Montuga) pacificum Murina

Phascolion (Montuga) pacificum Murina

Phascolion pacificum Murina, 1957: 1777 –1781

Type locality: Northwest Pacific, 5100–6900 m.

Remarks: Most of the 146 worms had been living in gastropod shells (some in scaphopod shells) and many had been damaged upon removal. Thus, body lengths are difficult to measure. They are all small, ranging from 2–10 mm, and have some limited array of V­ or U­shaped holdfast papillae on the posterior half of the trunk. These may be weakly developed, especially in the smaller worms.

The introvert retractor muscles appear as a single column until very near the posterior end where they divide into a pair of distinct roots.

Distribution. This bathyal and abyssal species (300–6900 m) is widespread at high latitudes in the northwestern and southwestern Pacific, the northeastern, southern and Antarctic Atlantic, and the subantarctic Indian Oceans, including northern Australia. While there are recorded populations at some distance to the west and southeast of New Zealand (Cutler, 1977a; Cutler et al., 2001), this material does suggest a more continuous, albeit not dense distribution.