The armored Harttia catfishes present great species diversity and remarkable cytogenetic variation, including different sex chromosome systems. Here we analyzed three new species, H. duriventris, H. villasboas and H. rondoni, using both conventional and molecular cytogenetic techniques (Giemsa-staining and C-banding), including the mapping of repetitive DNAs using fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH) experiments. Both H. duriventris and H. villasboas have 2n = ♀56/♂55 chromosomes, and an X1X1X2X2 /X1X2Y sex chromosome system, while a proto or neo-XY system is proposed for H. rondoni (2n = 54♀♂). Single motifs of 5S and 18S rDNA occur in all three species, with the latter being also mapped in the sex chromosomes. The results confirm the general evolutionary trend that has been noticed for the genus: an extensive variation on their chromosome number, single sites of rDNA sequences and the occurrence of multiple sex chromosomes. Comparative genomic analyses with another congeneric species, H. punctata, reveal that the X1X2Y sex chromosomes of these species share the genomic contents, indicating a probable common origin. The remarkable karyotypic variation, including sex chromosomes systems, makes Harttia a suitable model for evolutionary studies focusing on karyotype differentiation and sex chromosome evolution among lower vertebrates.

中文翻译：

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亚马逊鲶鱼的多性染色体和进化关系：Harttia 属的杰出模型（Siluriformes：Loricariidae）

装甲 Harttia 鲶鱼呈现出巨大的物种多样性和显着的细胞遗传变异，包括不同的性染色体系统。在这里，我们使用传统和分子细胞遗传学技术（吉姆萨染色和 C 显带）分析了三个新物种 H. duriventris、H. villasboas 和 H. rondoni，包括使用荧光原位杂交 (FISH) 绘制重复 DNA 的图谱和比较基因组杂交（CGH）实验。H. duriventris 和 H. villasboas 都有 2n = ♀56/♂55 染色体和 X1X1X2X2 /X1X2Y 性染色体系统，而 H. rondoni (2n = 54♀♂) 提出了 proto 或 neo-XY 系统。5S 和 18S rDNA 的单一基序出现在所有三个物种中，后者也被定位在性染色体中。结果证实了该属的普遍进化趋势：它们的染色体数量、rDNA 序列的单个位点和多条性染色体的出现发生了广泛的变化。与另一个同类物种 H. punctata 的比较基因组分析表明，这些物种的 X1X2Y 性染色体共享基因组内容，表明可能有共同的起源。显着的核型变异，包括性染色体系统，使 Harttia 成为进化研究的合适模型，重点是低等脊椎动物的核型分化和性染色体进化。表明可能的共同起源。显着的核型变异，包括性染色体系统，使 Harttia 成为进化研究的合适模型，重点是低等脊椎动物的核型分化和性染色体进化。表明可能的共同起源。显着的核型变异，包括性染色体系统，使 Harttia 成为进化研究的合适模型，重点是低等脊椎动物的核型分化和性染色体进化。