Abstract The ichnogenus Radulichnus Voigt, 1977 is recorded for the first time from a bivalve, Anomalocardia brasiliana (Gmelin, 1791), in a late Pleistocene molluskan assemblage from the southern Brazilian coastal plain. Grazing traces comprise short (<1 mm), parallel furrows, arranged in rows on the inner (concave) shell surface and mostly concentrated in its central area. Radulichnus accommodates scratches on hard substrates produced by the radula of grazing gastropod or polyplacophorans. Our literature survey on fossil and extant traces, as well as studies on the grazing mechanism in living mollusks, document at least two distinct morphotypes that are related to differences in the feeding modes of the producers. We propose to distinguish a second ichnospecies of Radulichnus, in addition to the type, R. inopinatus Voigt, 1977 (produced by gastropods), which is named R. transversus isp. nov., and attributed to polyplacophorans. Grazing traces on the shell of A. brasiliana match the morphotype produced by polyplacophorans mollusks, and are indicative of its complex taphonomic history in comparison with other shells in this assemblage.

中文翻译：

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来自巴西南部更新世双壳类动物的软体动物放牧痕迹 (Ichnogenus Radulichnus Voigt, 1977)，提出了一种新的物种

摘要 ichnogenus Radulichnus Voigt, 1977 首次从巴西南部沿海平原晚更新世软体动物组合中的双壳类动物 Anomalocardia brasiliana (Gmelin, 1791) 中发现。吃草痕迹包括短（<1 毫米）、平行的犁沟，排列在内（凹）壳表面上，主要集中在其中心区域。Radulichnus 可容纳由食草腹足类动物或多蠓类动物的轮缘产生的硬质基材上的划痕。我们对化石和现存痕迹的文献调查，以及对活软体动物的放牧机制的研究，记录了至少两种与生产者摄食方式差异相关的不同形态类型。我们建议区分 Radulichnus 的第二个 ichnospecies，除了类型，R. inopinatus Voigt，1977年（由腹足类产生），被命名为R. transversus isp。11 月，并归因于 polyplacophorans。A. brasiliana 壳上的放牧痕迹与 polyplacophorans 软体动物产生的形态类型相匹配，并表明与该组合中的其他壳相比，其复杂的埋藏历史。