Pimelodidae family is one of the most diverse and widely distributed fish groups in South America. Phylogenetic analysis in the family have recently indicated the existence of two main clades: "sorubiminae" and the OCP clade, including Pimelodus ornatus, "calophysines" and "pimelodines." The aim of this study was to investigate the karyotype of three Amazonian Pimelodidae species: Calophysus macropterus, Propimelodus eigenmanni, and Exallodontus aguanai associating them to the literature, seeking to reconstruct probable ancestral characters. C. macropterus has 2n = 50, 20m+20sm+10a (fundamental number [FN] = 90), simple interstitial nucleolar organizing regions (NORs), and four 5S rDNA sites terminals, two in synteny with the 18S rDNA. P. eigenmanni has 2n = 56, 28m+20sm+2st+6a (FN = 106), simple NORs, and two 5S rDNA sites terminals. E. aguanai has 2n = 56, 36m+12sm+2st+6a (FN = 106) and 18S and 5S rDNA sites interstitial syntenic in the chromosome 1. All species exhibited a higher amount of heterochromatin, differing from the pattern of the family, and strong marking associated with NORs. The integration between molecular phylogenetic data and karyotype data indicated a high probability that 2n = 56 and simple terminals NORs in the short arm are ancestral characters in Pimelodidae, evidenced in "sorubiminae." In the OCP clade derived traits were observed resulting from chromosomal changes that played a critical role in the karyotype evolution of the group.

中文翻译：

---

Calophysines和Exallodontus-Propimelodus进化枝（Pimelodidae，Siluriformes）的核型多样化：基于祖先状态重建的Pimelodidae的细胞分类和进化方法。

mel科（Pimelodidae family）是南美最多样化和分布最广的鱼类群之一。该家族的系统发育分析最近表明存在两个主要进化枝：“ sorubiminae”和OCP进化枝，包括Pimelodus ornatus，“ calophysines”和“ pimelodines”。这项研究的目的是调查三种亚科Pi亚科（Pimelodidae）的核型，将其与文献联系起来，以期重建可能的祖先特征。C. macropterus具有2n = 50、20m + 20sm + 10a（基本数字[FN] = 90），简单的间质核仁组织区（NORs）和4个5S rDNA位点末端，其中两个与18S rDNA并存。P.eigenmanni具有2n = 56，28m + 20sm + 2st + 6a（FN = 106），简单的NOR，和两个5S rDNA位点末端。E. aguanai在2号染色体上具有2n = 56、36m + 12sm + 2st + 6a（FN = 106）和18S和5S rDNA位点间质同位。所有物种的异染色质含量较高，与该家族的模式不同，以及与NOR相关的明显标记。分子系统发育数据和核型数据之间的整合表明，2n = 56和短臂中的简单末端NOR是Pi齿科的祖先特征的可能性很高，这在“狼蛛科”中得到了证明。在OCP进化枝中观察到了源自染色体变化的性状，这些变化在该组的核型进化中起关键作用。所有物种均显示出较高的异染色质含量，不同于该家族的模式，并且与NOR相关的标记很强。分子系统发育数据和核型数据之间的整合表明，2n = 56和短臂中的简单末端NOR是Pi齿科的祖先特征的可能性很高，这在“狼蛛科”中得到了证明。在OCP进化枝中观察到了源自染色体变化的性状，这些变化在该组的核型进化中起关键作用。所有物种均显示出较高的异染色质含量，不同于该家族的模式，并且与NOR相关的标记很强。分子系统发育数据和核型数据之间的整合表明，2n = 56和短臂中的简单末端NOR是Pi齿科的祖先特征的可能性很高，这在“狼蛛科”中得到了证明。在OCP进化枝中观察到了源自染色体变化的性状，这些变化在该组的核型进化中起关键作用。