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.

艾螺科（Eulimidae）腹足动物隶属于新腹足目（Caenogastropoda）瓦尼科罗螺总科（Vanikoroidea），是棘皮动物门（Echinodermata）的专性寄生生物，可寄生于该门的全部五个纲类群。然而多数种类拥有较长的自由生活阶段，且部分类群在采集过程中易从宿主身上脱落，这导致相关类群（尤其是深海类群）缺乏宿主相关的记录信息。本研究首次尝试检测艾螺体内残留的宿主DNA，以深入解析其寄生生态学特征。研究人员通过从吻部提取DNA、使用棘皮动物特异性引物开展聚合酶链式反应（PCR）并对亚克隆产物进行测序，成功鉴定出"海猪"——即平足目（Elasipodida）埃尔皮迪亚科（Elpidiidae）海猪属（*Scotoplanes*）的一种海参——为日本北部大陆坡半深海环境中采集的*Crinolamia*未定种此前未知的宿主。该艾螺物种与*Crinolamia*属模式种的形态相似性，对后者被认为与海百合存在关联的既定结论提出了质疑。