The axiidean families Callianassidae and Ctenochelidae, sometimes treated together as Callianassoidea, are shown to represent a monophyletic taxon. It comprises 265 accepted species in 74 genera, twice this number of species if fossil taxa are included. The higher taxonomy of the group has proved difficult and fluid. In a molecular phylogenetic approach, we inferred evolutionary relationships from a maximum-likelihood (ML) and Bayesian analysis of four genes, mitochondrial 16S rRNA and 12S rRNA along with nuclear histone H3 and 18S rRNA. Our sample consisted of 298 specimens representing 123 species plus two species each of Axiidae and Callianideidae serving as outgroups. This number represented about half of all known species, but included 26 species undescribed or not confidently identified, 9% of all known. In a parallel morphological approach, the published descriptions of all species were examined and detailed observations made on about two-thirds of the known fauna in museum collections. A DELTA (Description Language for Taxonomy), database of 135 characters was made for 195 putative species, 18 of which were undescribed. A PAUP analysis found small clades coincident with the terminal clades found in the molecular treatment. Bayesian analysis of a total-evidence dataset combined elements of both molecular and morphological analyses. Clades were interpreted as seven families and 53 genera. Seventeen new genera are required to reflect the molecular and morphological phylograms. Relationships between the families and genera inferred from the two analyses differed between the two strategies in spite of retrospective searches for morphological features supporting intermediate clades. The family Ctenochelidae was recovered in both analyses but the monophyly of Paragourretia was not supported by molecular data. The hitherto well recognised family Eucalliacidae was found to be polyphyletic in the molecular analysis, but the family and its genera were well defined by morphological synapomorphies. The phylogram for Callianassidae suggested the isolation of several species from the genera to which they had traditionally been assigned and necessitated 12 new generic names. The same was true for Callichiridae, with stronger ML than Bayesian support, and five new genera are proposed. Morphological data did not reliably reflect generic relationships inferred from the molecular analysis though they did diagnose terminal taxa treated as genera. We conclude that discrepancies between molecular and morphological analyses are due at least in part to missing sequences for key species, but no less to our inability to recognise unambiguously informative morphological synapomorphies. The ML analysis revealed the presence of at least 10 complexes wherein 2–4 cryptic species masquerade under single species names.

中文翻译：

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具有形态学支持的 Callianassidae 和相关科（甲壳纲：十足目：Axiidea）的分子系统发育

Axiidean 科 Callianassidae 和 Ctenochelidae，有时一起被视为 Callianassoidea，被证明代表一个单系分类群。它包括 74 个属中的 265 个公认的物种，如果包括化石分类群，则是这个物种数量的两倍。事实证明，该群体的更高分类是困难和流动的。在分子系统发育方法中，我们从四个基因的最大似然 (ML) 和贝叶斯分析推断进化关系，线粒体 16S rRNA 和 12S rRNA 以及核组蛋白 H3 和 18S rRNA。我们的样本包括代表 123 个物种的 298 个标本以及作为外群的 Axiidae 和 Callianideidae 各两个物种。这个数字代表了所有已知物种的大约一半，但包括 26 个未描述或不确定的物种，占所有已知物种的 9%。在平行形态学方法中，对已发表的所有物种的描述进行了检查，并对博物馆藏品中大约三分之二的已知动物群进行了详细观察。为 195 个推定物种制作了一个 DELTA（分类描述语言）数据库，包含 135 个字符，其中 18 个未描述。PAUP 分析发现小进化枝与分子处理中发现的末端进化枝一致。全证据数据集的贝叶斯分析结合了分子和形态分析的元素。进化枝被解释为 7 个科 53 个属。需要 17 个新属来反映分子和形态系统图。尽管对支持中间进化枝的形态特征进行了回顾性搜索，但从两种分析中推断出的科和属之间的关系在两种策略之间有所不同。在两次分析中都恢复了 Ctenochelidae 科，但分子数据不支持 Paragourretia 的单系。迄今为止公认的 Eucalliacidae 科在分子分析中被发现是多系的，但该科及其属在形态学突触中得到了很好的定义。Callianassidae 的系统图表明从传统上分配给它们的属中分离了几个物种，并需要 12 个新的属名。Callichiridae 也是如此，其 ML 比贝叶斯支持更强，并提出了五个新属。形态学数据并不能可靠地反映从分子分析中推断出的类属关系，尽管它们确实诊断了被视为属的末端分类群。我们得出结论，分子和形态分析之间的差异至少部分是由于关键物种的序列缺失，但同样是由于我们无法识别明确信息的形态突触。ML 分析揭示了至少 10 个复合体的存在，其中 2-4 个隐蔽物种伪装在单一物种名称下。