Data from: Hydrospire morphology and implications for blastoid phylogeny

The external expression of hydrospires in blastoids has provided a basis for major and minor group classification in the clade for over a century. Unfortunately, the complete anatomy of the hydrospires has never been comprehensively studied. This study examined and described the internal hydrospires of six spiraculate species by digitally extracting hydrospire data from a legacy data set of serial acetate peels. Although only six models have been currently generated, hydrospire morphology is variable both within and between previously described spiraculate families. Hydrospires were found to possess novel characters that were incorporated into a phylogenetic analysis of the six digitally modeled species and several related species. The addition of internal morphology into the phylogenetic analysis provides further resolution between groupings of blastoids.百余年来，海蕾（Blastoidea）的水孔（hydrospire）外部形态，一直是该演化支（clade）内各级类群分类的核心依据。遗憾的是，学界此前从未对水孔的完整解剖结构开展过系统性研究。本研究依托一套遗留的系列醋酸盐剥离制片（serial acetate peels）数据集，通过数字化提取水孔相关数据，对6种具水孔海蕾物种的内部水孔结构进行了检视与描述。尽管目前仅生成了6个数字化模型，但水孔形态在已发表的具水孔海蕾科内以及科间均存在显著变异。研究发现水孔具备全新的形态性状，我们将这些性状纳入对该6个数字化建模物种及若干近缘物种的系统发育分析（phylogenetic analysis）中。将内部形态数据纳入系统发育分析，进一步提升了海蕾类群分组间的系统发育分辨率。