Data from: Comparing phylogenetics and linear morphometrics to solve the generic assignment of Parabolinella? triarthroides Harrington (Trilobita, Olenidae)

The use of different methodological approaches together with an exhaustive qualitative study has helped to recognize important morphological traits to distinguish species in a systematic and phylogenetic framework. Parabolinella triarthroides Harrington, 1938 was described based on two cranidia from the Quebrada de Coquena, Purmamarca, Jujuy province. The generic assignment of P. triarthroides has been questioned by a phylogenetic analysis, which resolves this species as the sister group of Bienvillia Clark, 1924. To explore the generic assignment of this species, a revision of the type material, plus a morphometric analysis including specimens of Parabolinella Brøgger, 1882 and Bienvillia were performed. In addition, the original matrix used in the published phylogeny was reviewed and enlarged, including more species of Bienvillia. Continuous characters were coded in different ways in order to compare how they could affect the ordering of specimens and their phylogenetic relationships. Finally, both methodologies were compared, especially in regard to the behavior of the quantitative characters included in the analyses. From the combined analyses, it is shown that similarities between the cranidium of P. triarthroides and all other Parabolinella species are true homologies instead of a by-product of evolutionary convergence. Therefore, P. triarthroides should be considered a member of this genus. Finally, this study demonstrates that the best strategy for solving systematic problems in groups where the morphological variation is the only source of information (i.e., fossil taxa without living representatives) is the implementation of an integrative approach, combining different methodological techniques and a good description of specimens.

结合多种方法论手段与详尽的定性研究，得以识别出可在系统学与系统发育框架下区分物种的关键形态特征。1938年Harrington根据采自阿根廷胡胡伊省普马马尔卡地区科奎纳峡谷（Quebrada de Coquena）的两块头盖（cranidia），描述了三关节副博林三叶虫（Parabolinella triarthroides）Harrington, 1938。此前有系统发育分析对该种的属级归属提出质疑，该分析将本种复原为Bienvillia Clark, 1924（Bienvillia属）的姊妹群。为探究本种的属级归属，研究人员对其模式标本开展了修订，并实施了形态测量分析，分析对象涵盖副博林三叶虫属（Parabolinella Brøgger, 1882）与Bienvillia属的各类标本。此外，研究人员对已发表系统发育研究所使用的原始矩阵进行了梳理与扩充，纳入了更多Bienvillia属物种。为对比不同编码方案对标本排序及其系统发育关系的影响，研究人员以多种方式对连续性状进行编码。最后，研究人员对两种方法论开展了对比，尤其聚焦于分析中纳入的数量性状的表现情况。综合分析结果显示，三关节副博林三叶虫的头盖与其他副博林三叶虫物种间的相似性属于真正的同源性，而非演化趋同的产物。据此，本种应归入副博林三叶虫属。本研究证实，针对仅以形态变异为唯一信息来源的类群（即无现生代表的化石类群），解决其系统学问题的最佳策略是采用整合研究方法，结合多种方法论手段并对标本进行详尽描述。