Systematic value of the ultrastructure of the sucker surface in the squid family Mastigoteuthidae (Mollusca: Cephalopoda)

The ultrastructure of the sucker surface is described and its systematic value for mastigoteuthid squids, which bear minute suckers, is considered. An introduction to sucker terms is given and a redefinition of these terms is attempted. Using scanning electron microscopic data, two genera and four subgenera of Mastigoteuthidae from the Northwest Pacific are distinguished. The presence of “cushions” in the sucker is discussed and considered as a character important for understanding adaptations of cephalopods to the deep-sea.