Since their discovery, the systematic placement of two shrimp taxa, Amphionides and Procarididae, has been controversial. Both exhibit primitive features yet also possessing caridean traits. Amphionides was initially classified as a monotypic genus in the order Amphionidacea, while Procarididae was the only family in the superfamily Procaridoidea. Recent molecular studies have presented evidence that Amphionides is a larval form of pandalid shrimp, while Procaridoidea is elevated to an infraorder of Decapoda. To confirm the systematic status of the two shrimps, we report here the complete mitogenome sequences of Amphionides reynaudii and Procaris hawaiana. The phylogenetic tree of mitochondrial protein-coding genes from all decapod infraorders provides strong support for the systematic position of procaridid shrimp as the sister of Caridea, and the evolutionary divergence of the sequences substantiates the infraordinal status of Procarididae. The tree also verifies Amphionides as a caridean genus in Pandalidae, and further analysis using eight gene markers from the family indicates the sister relationship between Amphionides and Dorodotes. We also review the morphological characters of these two taxa and identify morphological features in support of their respective systematic status.

中文翻译：

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确认两种神秘虾，Amphionides 和 Procarididae（甲壳纲：十足目）的系统位置

自从他们被发现以来，对两种虾类群Amphionides和 Procarididae的系统放置一直存在争议。两者都表现出原始特征，但也具有caridean特征。Amphionides最初被归类为Amphionidacea 目中的一个单型属，而 Procarididae 是 Procaridoidea 总科中的唯一科。最近的分子研究表明，Amphionides是熊猫虾的幼虫形式，而 Procaridoidea 被提升为十足目虾的亚目。为了确认这两种虾的系统状态，我们在此报告了Amphionides reynaudii和Procaris hawaiana的完整有丝分裂基因组序列. 来自所有十足目下位纲的线粒体蛋白编码基因的系统发育树为原螯虾科作为 Caridea 的姐妹的系统地位提供了强有力的支持，并且序列的进化差异证实了原尾目虾科的下位地位。该树还验证了Amphionides是Pandalidae中的一个 caridean 属，使用来自该科的 8 个基因标记的进一步分析表明Amphionides和Dorodotes之间的姐妹关系。我们还回顾了这两个分类群的形态特征，并确定形态特征以支持它们各自的系统地位。