The karyotypes and chromosomal characteristics of three Acestrorhynchus Eigenmann et Kennedy, 1903 species were examined using conventional and molecular protocols. These species had invariably a diploid chromosome number 2n = 50. Acestrorhynchus falcatus (Block, 1794) and Acestrorhynchus falcirostris (Cuvier, 1819) had the karyotype composed of 16 metacentric (m) + 28 submetacentric (sm) + 6 subtelocentric (st) chromosomes while Acestrorhynchus microlepis (Schomburgk, 1841) had the karyotype composed of 14m+30sm+6st elements. In this species, differences of the conventional and molecular markers between the populations of Catalão Lake (AM) and of Apeu Stream (PA) were found. Thus the individuals of Pará (Apeu) were named Acestrorhynchus prope microlepis. The distribution of the constitutive heterochromatin blocks was species-specific, with C-positive bands in the centromeric and telomeric regions of a number of different chromosomes, as well as in interstitial sites and completely heterochromatic arms. The phenotypes of nucleolus organizer region (NOR) were simple, i. e. in a terminal position on the p arm of pair No. 23 except in A. microlepis, in which it was located on the q arm. Fluorescence in situ hybridization (FISH) revealed 18S rDNA sites on one chromosome pair in karyotype of A. falcirostris and A. prope microlepis (pair No. 23) and three pairs (Nos. 12, 23, 24) in A. falcatus and (Nos. 8, 23, 24) in A. microlepis; 5S rDNA sites were detected in one chromosome pair in all three species. The mapping of the telomeric sequences revealed terminal sequences in all the chromosomes, as well as the presence of interstitial telomeric sequences (ITSs) in a number of chromosome pairs. The cytogenetic data recorded in the present study indicate that A. prope microlepis may be an unnamed species.

中文翻译：

---

三种A（Acestrohynchinae，Characiformes）种间的细胞遗传关系揭示了可能存在的隐性物种。

使用常规方法和分子方法检查了1903个古猿（Acestrorhynchus Eigenmann等）的核型和染色体特征。这些物种的二倍体染色体数始终为2n =50。Acestrorhynchus falcatus（Block，1794）和Acestrorhynchus falcirostris（Cuvier，1819）的核型由16个亚中心（m）+ 28个亚中心（sm）+ 6个亚中心（st）染色体组成。而小额ce（Acestrorhynchus microlepis）（Schomburgk，1841）的核型由14m + 30sm + 6st元素组成。在该物种中，发现了CatalãoLake（AM）和Apeu Stream（PA）种群之间常规标记和分子标记的差异。因此，帕拉（Apeu）的个体被命名为Acestrorhynchus prope microlepis。组成型异染色质嵌段的分布是物种特异性的，在许多不同染色体的着丝粒和端粒区域以及间质位点和完全异色的臂中具有C阳性带。核仁组织区（NOR）的表型很简单，即在23号对p臂的末端位置，除了在A. microlepis中位于q臂的位置。荧光原位杂交（FISH）显示了A. falcirostris和A. prope microlepis（对23号）的核型中一个染色体对上的18S rDNA位点以及在A. falcatus和（A. falcatus（3）中的三对（Nos。12、23、24）。第8、23、24号）。在所有三个物种的一个染色体对中检测到5S rDNA位点。端粒序列的定位揭示了所有染色体中的末端序列，以及许多染色体对中存在间质端粒序列（ITS）。在本研究中记录的细胞遗传学数据表明，prop。microlepis可能是一个未命名的物种。