Ocean Species Discoveries 13–27 — Taxonomic contributions to the diversity of Polychaeta, Mollusca and Crustacea

This article presents 14 new species and one re-description, two new genera, with taxa spanning three phyla. Newly-described taxa comprise two polychaete annelids: <i>Nicon salinus</i> Hernández-Alcántara & Dávila-Jiménez, <b>sp. nov.</b> and <i>Spinther bohnorum</i> Tilic & Rouse, <b>sp. nov.</b> Molluscs span four classes, with three polyplacophorans: <i>Craspedochiton zefranki</i> Vončina, <b>sp. nov.</b>, <i>Ferreiraella charazata</i> Sigwart, <b>sp. nov.</b> and a new genus with type species <i>Pycnodontochiton sinensis</i> Sirenko, Zhang & Sigwart, <b>gen. et sp. nov.</b> and <i>Pycnodontochiton tenuidontus</i> (Saito and Okutani, 1990), <b>comb. nov.</b> The new monoplacophoran <i>Veleropilina gretchenae</i> Sigwart & Steger, <b>sp. nov.</b> is one of the first species of this class with a high-quality genome, published from the specimen that is now the holotype. The scaphopod <i>Laevidentalium wiesei</i> Sahlmann, 2012 represents a re-description and range extension and the bivalve <i>Myonera aleutiana</i> Machado & Sigwart, <b>sp. nov.</b> is the second bivalve including an anatomical description with non-invasive methods using micro-CT. Amongst crustaceans, there are two new amphipod species: <i>Apotectonia senckenbergae</i> Momtazi & Riehl, <b>sp. nov.</b> and <i>Metharpinia hirsuta</i> Souza-Filho & Andrade, <b>sp. nov.</b> Three isopod species were described, including the parasitic species <i>Zeaione everta</i> Boyko & Williams, <b>sp. nov.</b> that is the only species in the new genus <i>Zeaione</i> Boyko & Williams, <b>gen. nov.</b> and two free-living isopods: <i>Haploniscus bulbosus</i> Henseler, Knauber & Riehl, <b>sp. nov.</b> and <i>Macrostylis peteri</i> Riehl, <b>sp. nov.</b> Finally, there are two new tanaidaceans: <i>Hoplopolemius olo</i> Jóźwiak & Stępień, <b>sp. nov.</b> and <i>Nesotanais thalassinus</i> Stępień, <b>sp. nov.</b>The data used for the description of ten of the species and one of the new genera treated herein were wholly or partially obtained at the SOSA Discovery Laboratory using integrative methods including light and electron microscopy, confocal imaging, molecular barcoding and micro-CT scanning. Additional novel findings include the first record of the family Macrostylidae and the genus <i>Macrostylis</i> G. O. Sars, 1864 from Australian waters (<i>Macrostylis peteri</i>, <b>sp. nov.</b>) and novel host associations: <i>Ferreiraella charazata</i>, <b>sp. nov.</b> is documented with epibiotic tubeworms on its tail valves that are typical of this genus and the decapod <i>Eucalliaxiopsis aequimana</i> (Baker, 1907) is newly recorded as a host for bopyrid isopods, representing the first such record for the family Eucalliacidae.