Amended generic classification of the marine gastropod family Phenacolepadidae: transitions from snails to limpets and shallow-water to deep-sea hydrothermal vents and cold seeps

Benthic invertebrates at deep-sea hydrothermal vents and cold seeps have attracted considerable attention regarding their spatiotemporal distributions, colonization pathways, geological origins and morphological, ecological and physiological adaptations. Here we first reconstruct a molecular phylogeny for vent and seep species in the gastropod subclass Neritimorpha based on combined mitochondrial and nuclear gene sequences. The resulting tree, in conjunction with anatomical and palaeontological evidence, indicates that neritimorph snails and limpets in the Cenozoic deep-sea chemosynthetic habitats belong to the monophyletic subfamily Shinkailepadinae (family Phenacolepadidae). Confamilial shallow-water species form its sister clade, the subfamily Phenacolepadinae. There were probably at least three independent shifts from the coiled snail with a functional operculum to the limpet form in the evolutionary history of the family, twice in the deep-sea Shinkailepadinae and once in the shallow-water Phenacolepadinae. Physiological and ecological characteristics including the presence of red blood cells and larval migration seem to have facilitated their early Cenozoic colonization of vents and seeps. The type specimens of type species were investigated for most nominal genera to amend generic classification of this long-neglected family. A monotypic Divia gen. nov. is proposed for Shinkailepas briandi; Shinkailepas and Thalassonerita pre-date Olgasolaris and Bathynerita, respectively.

深海热液喷口和冷泉处的底栖无脊椎动物在其时空分布、定殖途径、地质起源以及形态、生态和生理适应性方面引起了相当大的关注。在此，我们首先基于线粒体和核基因序列组合，为腹足纲蜑螺亚纲的喷口和冷泉物种重建了分子系统发育树。由此产生的系统发育树，结合解剖学和古生物学证据表明，新生代深海化能合成生境中的蜑螺和帽贝属于单系的新笠贝亚科（笠贝科）。同科的浅水物种形成其姊妹分支，笠贝亚科。在该科的进化历史中，可能至少有三次从具有功能性厣的螺旋形螺到帽贝形态的独立转变，其中在深海新笠贝亚科中发生了两次，在浅水笠贝亚科中发生了一次。包括红细胞的存在和幼体迁移在内的生理和生态特征似乎促进了它们在新生代早期对喷口和冷泉的定殖。对大多数命名属的模式种的模式标本进行了研究，以修正这个长期被忽视的科的属级分类。为布氏新笠贝提出了一个单型属新属迪维亚；新笠贝和海笠贝分别早于奥尔加笠贝和深海笠贝。