Microgastropods in the subclass Caenogastropoda are diverse and species‐rich and often exhibit similar morphologies across families, posing difficulties for species identification. Spirostyliferina Bandel, 2006 is a microgastropod genus that has been placed in the family Litiopidae associated with algae and seagrass across the tropical Indo‐Pacific and with only one known member to date (Spirostyliferina lizardensis Bandel, 2006). There are uncertainties surrounding the familial assignment of Spirostyliferina however, due to its unique shell with spiral zigzag ridges, unique pitted protoconch and a lack of molecular data for phylogenetic analysis. This study aims to resolve the position of Spirostyliferina within the Caenogastropoda by employing a multilocus data set for phylogenetic reconstruction, and scanning electron microscopy and micro‐computed tomography for morphological analysis. Maximum likelihood and Bayesian phylogenies of 56 species, 30 families and six superfamilies of Caenogastropoda recovered Spirostyliferina within the Truncatelloidea. Spirostyliferina had no affinity with any existing truncatelloidean families, and therefore, the family Spirostyliferinidae fam. nov. is proposed for this genus. The genus Hoenselaaria Moolenbeek, 2009 was synonymized with Spirostyliferina in this study (monotypic Hoenselaaria wareni Moolenbeek, 2009). Spirostyliferinidae is diagnosed by heavy pitted microsculpture on protoconch I and intermittent spiral zigzag ridges on the teleoconch. The unpegged corneous operculum and taenioglossate radula of Spirostyliferina appear similar to other truncatelloideans, confirming the position of Spirostyliferina as a monotypic clade within the Truncatelloidea. In all, this study advances the taxonomic status of a microgastropod with a minute size and rarity that presents significant challenges to its collection and study.

中文翻译：

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为 Spirostyliferina 建立一个新科，一种截形小腹足类动物，并进一步了解截形纲的系统发育

Caenogastropoda 亚纲中的小腹足动物种类繁多且物种丰富，并且在各科之间通常表现出相似的形态，这给物种鉴定带来了困难。Spirostyliferina Bandel, 2006 是一种小腹足类属，已被置于与热带印度洋-太平洋的藻类和海草相关的 Litiopidae 科中，迄今为止只有一个已知成员 (Spirostyliferina lizardensis Bandel, 2006)。然而，Spirostyliferina 的家族分配存在不确定性，因为它具有螺旋形锯齿脊的独特外壳、独特的有凹痕的原贝壳以及缺乏用于系统发育分析的分子数据。本研究旨在通过使用多位点数据集进行系统发育重建来确定 Spirostyliferina 在 Caenogastropoda 中的位置，用于形态学分析的扫描电子显微镜和显微计算机断层扫描。Caenogastropoda 的 56 个物种、30 个科和 6 个超科的最大似然和贝叶斯系统发育在 Truncatelloidea 中恢复了 Spirostyliferina。Spirostyliferina 与任何现有的 truncatelloidean 科没有亲缘关系，因此与 Spirostyliferinidae 家族没有任何关系。十一月 建议用于该属。在本研究中，Hoenselaaria Moolenbeek 属，2009 与 Spirostyliferina 同义（单型 Hoenselaaria wareni Moolenbeek，2009）。Spirostyliferinidae 通过原始贝壳 I 上的大量凹坑微雕和远贝壳上的间歇性螺旋锯齿形脊来诊断。Spirostyliferina 的未固定的角质鳃盖和 taenioglossate radula 看起来与其他截形纲动物相似，确认 Spirostyliferina 在 Truncatelloidea 中作为单型进化枝的位置。总而言之，这项研究提高了微小腹足类动物的分类地位，其体积小且稀有，这对其收集和研究提出了重大挑战。