Abstract A new fossil apseudomorphan tanaidacean, Protoapseudoidus espinalensis gen. et n. sp., from the Chiapas Region of Mexico, is described and placed within the new monotypic family Protoapseudoidae. Its description is based on more than 1000 specimens collected from the Lower Cretaceous (Aptian) in laminar dolomites from the El Espinal quarries (Sierra Madre Formation). The presence of a telsonic somite partially fussed, but ventrally distinct indicates that the body form of this new tanaidacean may represent a transitional evolutionary step between fossil Anthracocaridomorpha and the extant Apseudomorpha. The presence of an apparently fused, but a ventrally delineated telsonic somite indicates that the new family may represent a transition of an anthracocaridomorphan to an apseudomorphan body form. A new family, the Protoapseudoidae, is designated to accommodate the unique combination of morphological features exhibited by the new Chiapas species. These features include the presence of a vestigial telson, a blunt subtriangular rostrum, vestigial anterolateral processes on the carapace, and a single male genital cone, coupled with the absence of eye stalks, coxal spine on the first pereopod, and spines or lateral processes on carapace and pereon. This combination of characters distinguishes the new family from all the other known extinct and extant families within the Order Tanaidacea. Though clearly indicated ventrally, unlike the Anthracocaridomorphan, the vestigial telsonic somite of new Chiapas family appears not to be “independent” or “articulated,” and is functionally fused with pleonite-6 to form a pleotelson. Accordingly, the new family is tentatively placed within the suborder Apseudomorpha. The Protoapseudoidae appears, at least superficially, to have possible affinities with both the Paleozoic genus Ophthalmapseudes and to the members of the extant parapseudid Discapseudes-Halmyrapseudes Complex. The Paleozoic anthracocaridid genera Eucryptocaris and Ophthalmapseudes, due to their unique morphological features and temporal distances, are hierarchized to family rank. Based on their high morphological similarity, members of the apseudomorphan superfamily Jurapseudoidea are subsumed into the superfamily Apseudoidea. The possible relationship between the extinction of Protoapseudoidae and the emergence of parapseudid tanaidaceans in Americas is discussed. The morphological changes recorded between the Cretaceous fossil tanaidaceans, including the review of those 25 species as far known, and their extant relatives are considered to propose the timelines on the evolution of different tanaidacean morphotypes. Also, here are discussed the taphonomic and paleoenvironmental Condition that allow the fossil preservation of tanaidaceans.

中文翻译：

---

墨西哥恰帕斯下白垩统（Aptian）的新科、属和种（甲壳纲；假形纲）：系统修正和古环境观察

摘要 一种新的假象门类化石，Protoapseudoidus espinalensis gen。et n. 来自墨西哥恰帕斯地区的 sp. 被描述并置于新的单型家族 Protoapseudoidae 中。它的描述是基于从 El Espinal 采石场（Sierra Madre 组）的层状白云岩中收集的 1000 多个样本，这些标本是从下白垩统（Aptian）收集的。telsonic 体节的存在部分混乱，但腹侧不同表明这种新的 tanaidacean 的体型可能代表化石 Anthracocaridomorpha 和现存的 Apseudomorpha 之间的过渡进化步骤。一个明显融合但在腹侧划定的 telsonic 体节的存在表明这个新家族可能代表了炭疽螈体向假螈体形式的转变。一个新的家族，原假蜂科，被指定适应新恰帕斯物种表现出的形态特征的独特组合。这些特征包括存在残留的尾骨、钝的下三角喙、背甲上残留的前外侧突起和单个雄性生殖器锥体，再加上没有眼柄、第一个脚足上的髋棘和棘或侧突甲壳和pereon。这种字符组合将新科与塔奈达科内所有其他已知的已灭绝和现存科区分开来。虽然在腹侧有明确的指示，但与 Anthracoccaridomorphan 不同，新恰帕斯家族的残余 telsonic 体节似乎不是“独立的”或“铰接的”，并且在功能上与 pleonite-6 融合形成一个 pleotelson。因此，新科暂时归入伪形亚目。Protoapseudoidae 似乎，至少在表面上，与古生代 Ophthalmapseudes 属和现存的近端假足类 Discapseudes-Halmyrapseudes 复合体的成员有可能的亲缘关系。古生代炭疽菌属 Eucryptocaris 和 Ophthalmapseudes，由于它们独特的形态特征和时间距离，被划分为科等级。基于它们高度的形态相似性，拟螟总科 Jurapseudoea 的成员被归入伪螈总科。讨论了原蝾螈科的灭绝与美洲拟蝾螈类的出现之间的可能关系。记录的白垩纪化石tanaidaceans之间的形态变化，包括对目前已知的这 25 个物种的审查，以及它们现存的亲属被认为提出了不同 tanaidacean 形态类型进化的时间表。此外，这里还讨论了允许 tanaidaceans 化石保存的地埋地学和古环境条件。