DNA-based identification of an echinoderm host for a deep-sea parasitic snail (Gastropoda: Eulimidae)

Eulimid gastropods (Caenogastropoda: Vanikoroidea) are exclusive parasites of echinoderms including all five classes of the phylum. However, many species have a long autonomous period and some tend to fall off the host during collection. This may result in a lack of host information for taxa, particularly those from the deep sea. The present study represents the first attempt to analyse the possible remains of host DNA in eulimid snails for a better understanding of their parasitic ecology. DNA extraction from the proboscis, polymerase chain reaction (PCR) with echinoderm-specific primers and sequencing of subclones successfully identified the ‘sea pig’, a holothurian of the genus <i>Scotoplanes</i> (Elasipodida: Elpidiidae) as the previously unknown host of <i>Crinolamia</i> sp. from bathyal depths off northern Japan. The morphological similarity between this eulimid and the type species of <i>Crinolamia</i> questions the alleged association of the latter with crinoids.