Here we describe a new species of shallow-subtidal nudibranch from south-eastern Africa. The strikingly vivid orange sea slug with white markings belongs to the long-disputed family Facelinidae, and has been photographed and recorded in the region by divers for some time. Tomographic modelling was applied to produce a 3D anatomical reconstruction of the reproductive and digestive organs from serial sections. A molecular phylogeny using multiple markers (cytochrome c oxidase subunit I, 16S rRNA and histone H3) recovered three distinct clades within the paraphyletic Facelinidae, in agreement with other recent studies. This topology supported a genus-level clade, including the type species of Sakuraeolis Baba, 1965, S. enosimensis Baba, 1930, the new species described herein, S. arcana n. sp., and an undescribed sibling species that shares morphological resemblance to S. arcana n. sp. Facelina quatrefagesi Vayssière, 1888 is also recognized as Caloria quatrefagesi n. comb. on the basis of molecular and morphology affinity. Field observations provided insight into phenology, with a population decline noted in August. Although the new species does not have the penial structure previously considered diagnostic for Sakuraeolis, the decision was made on the balance of evidence for phylogenetic affinity to amend the diagnosis of the genus to accommodate S. arcana n. sp.

中文翻译：

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一种来自莫桑比克的 Sakuraeolis 新物种，使用 3D 解剖结构重建和系统发育分析进行描述

在这里，我们描述了来自非洲东南部的一种新的浅潮下带裸鳃类动物。这种带有白色斑纹的橙色海蛞蝓非常鲜艳，属于备受争议的海蛞蝓科，潜水员在该地区拍摄和记录了一段时间。应用断层扫描建模从连续切片生成生殖和消化器官的 3D 解剖重建。与最近的其他研究一致，使用多个标记（细胞色素 c 氧化酶亚基 I、16S rRNA 和组蛋白 H3）的分子系统发育恢复了并系 Facelinidae 内的三个不同进化枝。这种拓扑结构支持一个属级进化枝，包括 Sakuraeolis Baba，1965 年，S. enosimensis Baba，1930 年的模式物种，本文描述的新物种，S. arcana n。sp., 和一个未描述的同胞物种，与 S. arcana n 具有形态相似性。sp。Facelina quatrefagesi Vayssière，1888 年也被认为是 Caloria quatrefagesi n。梳子。基于分子和形态亲和性。实地观察提供了对物候学的深入了解，8 月份出现了人口下降。尽管这个新物种没有以前被认为可诊断为 Sakuraeolis 的阴茎结构，但还是根据系统发育亲和性的证据平衡做出了修改该属的诊断以适应 S. arcana n. 的决定。sp。尽管这个新物种没有以前被认为可诊断为 Sakuraeolis 的阴茎结构，但还是根据系统发育亲和性的证据平衡做出了修改该属的诊断以适应 S. arcana n. 的决定。sp。尽管这个新物种没有以前被认为可诊断为 Sakuraeolis 的阴茎结构，但还是根据系统发育亲和性的证据平衡做出了修改该属的诊断以适应 S. arcana n. 的决定。sp。