Department of Evolutionary Biology, University of Vienna, Vienna, Austria.
Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
J Morphol. 2024 Sep;285(9):e21770. doi: 10.1002/jmor.21770.
Terebriporidae is one of the four extant endolithic ctenostome bryozoan families, with colonies immersed into carbonate substrates like molluscan shells. This monogeneric family comprises 17 species, with 11 extant and 6 fossil species. It is currently considered closely related to vesicularioid ctenostomes, a group characterized by colonies interconnected by polymorphic stolons and a distinct gizzard as part of their digestive systems. However, confusion persists regarding the correct species identities and affiliations of many terebriporid species, and even the description of the entire family is based solely on a few external features of their boring traces, rendering the family an ichnotaxon (trace fossil). Our molecular analysis does not support a vesicularioid affinity, but corroborate a close relationship to Immergentia, another genus of boring bryozoans. Consequently, this study aims to untangle the systematic confusion surrounding Terebriporidae by examining the tracemaker of the type species of the family, Terebripora ramosa from Chile, and investigating its morphology and histology using modern techniques. The current analysis could not confirm typical vesicularioid characters such as a gizzard or true polymorphic stolons. Instead, all characters point towards a closer relationship to Immergentiidae as suggested by a recent molecular phylogeny. In fact, these two taxa share several characters such as cystid appendages and duplicature bands, and appear closely related, with the only difference being a characteristic vane with tubulets present in the tracemaker of T. ramosa. The sister-group relationship of the tracemaker and the genus Immergentia infers that these borers share a common boring ancestor, but also emphasizes that additional species from the ichnogenus Terebripora need to be studied for more clarity.
Terebriporidae 是现存的四个内栖栉水母动物门苔藓动物家族之一，其群体沉浸在碳酸盐基质中，如软体动物的壳。这个单种科包括 17 个物种，其中 11 个现存，6 个化石。它目前被认为与泡状栉水母密切相关，泡状栉水母是一个群体，其特征是由多态性的匍匐茎连接的群体，以及作为其消化系统一部分的独特的胃石。然而，许多 terebriporid 物种的正确物种身份和归属仍然存在混淆，甚至整个家族的描述仅基于其钻孔痕迹的几个外部特征，使得该家族成为一个遗迹生物群（痕迹化石）。我们的分子分析不支持泡状栉水母的亲缘关系，但证实了与另一种钻孔苔藓动物 Immergentia 的密切关系。因此，本研究旨在通过检查智利 ramosa 属的模式种的造迹生物来理清围绕 Terebriporidae 的系统混乱，并使用现代技术研究其形态和组织学。目前的分析无法证实典型的泡状栉水母特征，如胃石或真正的多态性匍匐茎。相反，所有特征都表明与 Immergentiidae 的关系更为密切，正如最近的分子系统发育所表明的那样。事实上，这两个分类群有几个共同的特征，如胞囊附属物和双折叠带，并且看起来密切相关，唯一的区别是在 ramosa 属的造迹生物中存在带有小管的特征叶片。造迹生物与属 Immergentia 的姐妹群关系推断出这些钻孔生物具有共同的钻孔祖先，但也强调需要研究更多的 ichnogenus Terebripora 物种以获得更清晰的认识。
