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.

一个多世纪以来，海蕾类（blastoids）的水芽（hydrospire）外部形态一直是该演化支内大类群与小类群分类的核心依据。遗憾的是，学界从未对水芽的完整解剖结构开展过系统性研究。本研究通过从连续乙酸盐剥离复型片的遗留数据集中数字化提取水芽相关数据，对6个具呼吸孔海蕾物种的内部水芽结构进行了检视与描述。尽管目前仅构建了6个数字化模型，但研究发现水芽的形态在已报道的具呼吸孔海蕾科内以及科间均存在显著变异。本研究发现水芽具备若干此前未被记录的新性状，并将这些新性状纳入对该6个数字化建模物种及若干近缘物种的系统发育分析中。将内部形态数据纳入系统发育分析后，海蕾类各演化支间的系统发育分辨率得到了进一步提升。