Paracalliactis cf. involvens (McMurrich, 1893)

Paracalliactis cf. involvens View in CoL

( McMurrich, 1893)

Fig. 4F View Fig .

Adamsia involvens McMurrich, 1893: 182 View in CoL .

Paracalliactis involvens View in CoL : Carlgren, 1947: 15; 1949: 95.

MATERIAL. LV-82-10, 55.2902°N 167. 3009ºE – 55.2898°N 167.2974ºE, depth 2755– 2638 m, one specimen collected (sample 3) and seven specimens photographed.

REMARKS. This species is an obligate symbiont that lives on the shell of gastropods inhabited by hermit crabs. It can reach 10 cm in length in extended state. Its pedal disc covers the whole shell and capable to form carcinoecium. The column and the margin are smooth, the scapus is covered with a thin cuticle, sometimes with a layer of mud. The scapulus, the limbus and the tentacles are rose-orange. Underwater photos and videos on the southern slope of the Vulcanologov Massif recorded 10 specimens, one of which was collected.

Daly et al. (2004) synonymized Pacific P. involvens and North Atlantic P. consors (Verrill, 1882) . However, P. consors has coronal tubercles covered by cuticle ( Molodtsova et al., 2008), similar to those reported for syntypes of P. consors , which are probably characteristic for the Atlantic species.The known specimens from the Pacific Ocean have no such tubercles. Thus, at present, we prefer to separate the Atlantic and Pacific species and consider them as two species.