The recently-revised subfamily Centruroidinae is part of the New World clade of buthid scorpions. In this study, we analyzed the cytogenetic characteristics of nine of the 10 Brazilian centruroidines, and one undescribed species of the genus Ischnotelson, using a phylogenetic approach to determine the chromosomal rearrangements responsible for the differentiation of karyotypes among the species. The cytogenetic data recorded in the present study supported the new taxonomic arrangement of the Centruroidinae, with all the species of the same genus sharing the same or similar diploid numbers, i.e., 2n = 20 or 22 in Troglorhopalurus lacrau and T. translucidus, 2n = 25 or 26 in Ischnotelson sp., I. guanambiensis and I. peruassu, and 2n = 28 in Jaguajir agamemnon, J. pintoi and J. rochae. The karyotype modelling in the ChromEvol software indicated 2n = 18 as the ancestral diploid number of the Centruroidinae. The differentiation of karyotypes among the centruroidine genera was based on increasing chromosome numbers resulting from progressive fission events. These changes probably occurred prior to the diversification of the genera Ischnotelson, Jaguajir, Physoctonus and Rhopalurus, and appear to have played a more important role in karyotype evolution at the intergeneric level than the interspecific one. However, the observed increase in diploid numbers was not accompanied by changes in the number or location of ribosomal genes or telomeric sequences. The identification of meiotic cells in female specimens also allowed us to discuss the mechanisms of achiasmatic meiosis in scorpions.

中文翻译：

---

巴西蝎亚科 Centruroidinae (Buthidae) 的核型进化机制

最近修订的亚科 Centruroidinae 是新世界蝎子分支的一部分。在这项研究中，我们分析了 10 种巴西丝核苷中的 9 种和一种未描述的 Ischnotelson 属物种的细胞遗传学特征，使用系统发育方法来确定负责物种间核型分化的染色体重排。本研究中记录的细胞遗传学数据支持 Centruroidinae 的新分类排列，同一属的所有物种共享相同或相似的二倍体数，即 Troglorhopalurus lacrau 和 T. translucidus 中的 2n = 20 或 22，2n =在 Ischnotelson sp.、I. guanambiensis 和 I. peruassu 中为 25 或 26，在 Jaguajir agamemnon、J. pintoi 和 J. rochae 中为 2n = 28。ChromEvol 软件中的核型建模表明 2n = 18 作为 Centruroidinae 的祖先二倍体数。核苷属之间核型的分化是基于渐进性裂变事件导致的染色体数量增加。这些变化可能发生在 Ischnotelson、Jaguajir、Physoctonus 和 Rhopalurus 属的多样化之前，并且似乎在属间水平的核型进化中发挥了比种间更重要的作用。然而，观察到的二倍体数量的增加并未伴随核糖体基因或端粒序列的数量或位置的变化。雌性标本中减数分裂细胞的鉴定也使我们能够讨论蝎子中无交叉减数分裂的机制。