AUTHOR=Passos Flávio Dias , Corrêa Paulo Vinicius Ferraz , Miranda Marcel Sabino 

TITLE=Better Alone Than in Bad Company: New Species of Caudofoveate Limifossorid (Mollusca, Aplacophora) Unravels Patterns of Distribution Hidden in the Deep Atlantic

JOURNAL=Frontiers in Marine Science

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2021.669478

DOI=10.3389/fmars.2021.669478

ISSN=2296-7745

ABSTRACT=<p>Aplacophorans are common inhabitants of the deep-sea, where many places remain unexplored regarding their biodiversity. Filling a gap in knowledge about these animals from the South Atlantic, <italic>Scutopus variabilis</italic> sp. nov. (Caudofoveata, Limifossoridae) is described; further, species distribution modelling (SDM) was performed to elucidate the distribution patterns of Atlantic species of <italic>Scutopus</italic>. The type materials of <italic>S. megaradulatus</italic><xref ref-type="bibr" rid="B40">Salvini-Plawen (1972)</xref> and <italic>S. chilensis</italic><xref ref-type="bibr" rid="B40">Salvini-Plawen (1972)</xref>, were examined and a search was performed for specimens of <italic>Scutopus</italic> held in museum collections. <italic>Scutopus variabilis</italic> sp. nov. has a slender and highly variable body form and a very distinct suture line is present midventrally. Two dominant types of trunk sclerites were observed by Scanning Electron Microscopy (SEM): one elongated with lateral margins slightly concave in medial portion, and another longer, with narrower base; its radula bears up to eight rows of heavily sclerotized teeth bearing 12–16 small denticles. The species occurs in a wide bathymetric range (40–1300 m), being more abundant at the edge between the continental shelf and upper slope. Outside the areas from where these samples were obtained, suitable areas for <italic>S. variabilis</italic> sp. nov. were found in the Southern Caribbean Sea (from where <italic>S. megaradulatus</italic> is recorded) and in the Brazilian Northern coast; the Gulf of Mexico and the Brazilian Northeastern coasts were found as unsuitable. Species of <italic>Scutopus</italic> appear to exhibit different patterns of geographical distribution: the European <italic>S. ventrolineatus</italic><xref ref-type="bibr" rid="B37">Salvini-Plawen (1968)</xref> and <italic>S. robustus</italic><xref ref-type="bibr" rid="B39">Salvini-Plawen (1970)</xref> are known as widely distributed, while non-European representants, the American <italic>S. megaradulatus</italic>, <italic>S. chilensis</italic> and <italic>S. variabilis</italic> sp. nov., and the Japanese <italic>S. schanderi</italic><xref ref-type="bibr" rid="B36">Saito and Salvini-Plawen (2014)</xref> and <italic>S. hamatamii</italic><xref ref-type="bibr" rid="B36">Saito and Salvini-Plawen (2014)</xref> have more restricted distributions. However, clear and definite patterns of distribution of some of these species are probably blurred by sampling bias, for the European area is better studied. In the Atlantic, the SDM showed that species of <italic>Scutopus</italic> occur in a way that overlapping is minimized. Great sampling efforts combined with detailed descriptions based on SEM have revealed an interesting, abundant and up to now undescribed Brazilian deep-sea malacofauna.</p>