Cytogenetics and DNA barcoding of the Round-eared bats, Tonatia (Chiroptera: Phyllostomidae): a new karyotype for Tonatia bidens

ABSTRACT There are two species of Neotropical Round-eared bats, Tonatia bidens Spix, 1823 and Tonatia saurophila Koopman & Williams, 1951, which present highly similar morphological characteristics that can lead to errors of identification. Specimens originally identified as T. bidens have recently been reclassified as T. saurophila, and the only karyotype documented previously for these species was 2n = 16, FN = 20. In the present study, specimens of Tonatia collected in the municipality of Barra do Garças, in the Brazilian state of Mato Grosso, were analyzed morphologically, using conventional cytogenetic techniques (C-banding, Ag-NOR, and CMA3), and through sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene. In the specimens morphologically identified as T. bidens, the diploid number (2n) was 26, and the fundamental number (FN), 38, while in T. saurophila, 2n = 16 and FN = 20, which is the karyotype also described previously for T. bidens. The dendograms obtained with sequences of the COI marker resulted in the formation of two distinct groups between T. bidens and T. saurophila, consistent with the two species, with a high sequence divergence value (14.22%). Distinct clades were also observed between T. bidens and the other phyllostomines analyzed in this study, with T. bidens also close to Phyllostomus hastatus (14.18% of sequence divergence).

摘要：新热带界圆耳蝠类（Neotropical Round-eared bats）包含两个物种，即1823年由Spix命名的Tonatia bidens Spix, 1823与1951年由Koopman及Williams命名的Tonatia saurophila，二者形态特征高度相似，极易引发物种鉴定误差。此前最初被鉴定为T. bidens的标本，近期已被重新归类为T. saurophila；且该类群此前仅记录过一种核型：二倍体染色体数（2n）=16，染色体臂数（FN）=20。本研究对采集自巴西马托格罗索州巴拉杜加萨斯市的圆耳蝠属（Tonatia）标本开展了形态学分析，同时采用常规细胞遗传学技术（C带、银染核仁组织区（Ag-NOR）染色及色霉素A3（CMA3）染色），并基于线粒体细胞色素c氧化酶亚基I（COI）基因序列开展分析。结果显示，经形态学鉴定为T. bidens的标本，其二倍体染色体数为26，染色体臂数为38；而T. saurophila的核型为2n=16、FN=20，这与此前针对T. bidens报道的核型一致。基于COI标记序列构建的系统发育分支图（dendograms）显示，T. bidens与T. saurophila分为两个独立类群，符合二者的物种分类地位，序列分歧度高达14.22%。此外，本研究中T. bidens与其余被分析的叶口蝠亚科（phyllostomines）物种也形成了独立演化支，且T. bidens与Phyllostomus hastatus的序列分歧度为14.18%，二者亲缘关系较近。