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.

两个产自中二叠世（卡匹敦期）至早三叠世（格里斯巴赫期）的皱纹长身贝科（Rugosochonetidae）腕足动物属——富县长身贝属（Fusichonetes Liao in Zhao et al., 1981）与特提斯长身贝属（Tethyochonetes Chen et al., 2000），长期以来被视为两个独立类群，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-三叠纪界线大灭绝等诸多议题的讨论中。然而，这两个类群所谓的形态差异即便存在也极为细微，实则代表了形态连续变化谱系的两个端元。本研究针对15项整合了关键外部与内部性状的定量形态变量数据集，采用二元散点图、柯尔莫哥洛夫-斯米尔诺夫检验、分类主成分分析以及分支系统学分析等一系列定量分析流程，对所有已确认的富县长身贝属与特提斯长身贝属的141件标本进行测量，以验证基于所选性状能否区分这两个属。研究结果显示，这两个属在形态上无法区分，且此前应用于这两个属的物种分类，实则属于富县长身贝属内部的复系群组合。据此，本研究认定特提斯长身贝属为富县长身贝属的晚出异名。基于采自华南地区二叠纪-三叠纪新民剖面的一批保存完好的新标本，本研究厘清并修订了富县长身贝属的鉴别特征与核心性状。