The pearly razorfish Xyrichtys novacula (Linnaeus, 1758) is a sedentary benthic species distributed in both sides of the Atlantic Ocean and in the Mediterranean Sea. Previous cytogenetic analysis reported different diploid numbers in samples from Italy, Venezuela and Brazil. This research aims to test the hypothesis that samples from American Atlantic coast and Mediterranean Sea belong to the same single evolutionary lineage, characterized by intra-specific chromosome polymorphism. To this purpose a cytogenetic and molecular (mitochondrial COI sequences) survey was undertaken. Results revealed the existence of three different pearly razorfish molecular lineages: one present in Mediterranean Sea and two in the central and south American area, which are characterized by different karyotypes. One of these lineages shows substantial intra-population chromosomal polymorphism (2n = 45–48) determined by Robertsonian fusions that produce large metacentric chromosomes. On the whole data suggest that specimens morphologically identified as X. novacula correspond to three cryptic species.

中文翻译：

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珍珠剃刀鱼 Xyrichtys novacula（唇形目、唇形目）的染色体多态性和分子变异性：分类学和生物地理学意义

珍珠剃刀鱼 Xyrichtys novacula (Linnaeus, 1758) 是一种久坐的底栖物种，分布于大西洋两岸和地中海。之前的细胞遗传学分析报告了来自意大利、委内瑞拉和巴西的样本中不同的二倍体数量。本研究旨在检验来自美洲大西洋沿岸和地中海的样本属于同一单一进化谱系的假设，其特征是种内染色体多态性。为此目的，进行了细胞遗传学和分子（线粒体 COI 序列）调查。结果揭示了三种不同的珍珠剃刀鱼分子谱系的存在：一种存在于地中海，两种存在于中美洲和南美洲地区，其特征在于不同的核型。这些谱系之一显示出大量的种群内染色体多态性（2n = 45-48），由产生大的中心染色体的罗伯逊融合决定。整体数据表明，形态学上鉴定为 X. novacula 的标本对应于三个隐匿物种。