Data from: A quantitative taxonomic review of Fusichonetes and Tethyochonetes (Chonetidina, Brachiopoda)

Two middle Permian (Capitanian) to Early Triassic (Griesbachian) rugosochonetidae brachiopod genera, Fusichonetes Liao in Zhao et al., 1981 and Tethyochonetes Chen et al., 2000, have been regarded as two distinct taxa and used as such for a wide range of discussions including biostratigraphy, paleoecology, paleobiogeography, and the Permian-Triassic boundary mass extinction. However, the supposed morphological distinctions between the two taxa are subtle at best and appear to represent two end members of a continuum of morphological variations. In this study, we applied a range of quantitative and analytical procedures (bivariate plots, Kolmogorov-Smirnov test, categorical principle component analysis, and cladistic analysis) to a dataset of 15 quantified morphological variables, integrating both key external and internal characters, measured from 141 specimens of all well-known Fusichonetes and Tethyochonetes in order to test whether or not these two genera could be distinguished in view of the chosen characters. The results indicate that these two genera are morphologically indistinguishable and that the species classification previously applied to these two genera appears to represent polyphyletic groupings within the genus Fusichonetes. Consequently, Tethyochonetes is concluded to be a junior synonym of Fusichonetes. The diagnosis and key characteristics of Fusichonetes are clarified and refined based on a new suite of well-preserved specimens from the Permian−Triassic Xinmin section in South China.产自中二叠世（卡匹敦期）至早三叠世（格里斯巴赫期）的皱纹贝科（Rugosochonetidae）腕足动物包含两个属：皱饰贝属（Fusichonetes Liao in Zhao et al., 1981）与特提斯皱饰贝属（Tethyochonetes Chen et al., 2000）。二者长期被视为两个独立的分类单元，并被广泛应用于生物地层学、古生态学、古生物地理学以及二叠纪-三叠纪之交大灭绝等诸多研究议题中。然而，二者被推测存在的形态差异充其量仅为细微之别，实则代表了形态变异连续体的两个端元。本研究针对包含15个定量化形态变量、整合关键外部与内部性状的数据集，采用双变量散点图、柯尔莫哥洛夫-斯米尔诺夫检验（Kolmogorov-Smirnov test）、分类主成分分析（categorical principal component analysis）以及支序分析等多种定量分析方法，对141件涵盖所有已知皱饰贝属与特提斯皱饰贝属标本的形态测量数据进行分析，以检验基于所选性状能否区分这两个属。分析结果显示，二者在形态上并无显著差异，且此前基于这两个属建立的物种分类单元，实则为皱饰贝属（Fusichonetes）内的多系类群。因此，特提斯皱饰贝属（Tethyochonetes）应被视为皱饰贝属（Fusichonetes）的晚出同物异名。本研究基于中国华南地区二叠纪-三叠纪新民剖面的一批保存完好的新标本，对皱饰贝属（Fusichonetes）的鉴别特征与核心性状进行了厘定与修订。