Gonatoxia helleri Hemp, 2016 is one of the most widespread bush-crickets of the genus Gonatoxia Karsch, 1889 in East Africa. This species with seven large chromosomes (2n♂ = 7) differs from other representatives of the genus Gonatoxia drastically by its reduced chromosome number, the asymmetrical karyotype including karyomorphs rarely found in tettigoniids, as well as in irregularities in the course of meiosis. To better understand the origin of such an exceptional karyotype, chromosomes of 29 specimens from four populations/localities were studied using classical techniques, such as C-banding, silver impregnation, fluorochrome double staining and fluorescence in situ hybridization (FISH) technique with 18S rDNA and (TTAGG)n telomeric probes. FISH showed many 18S rDNA loci as well as interstitial telomeric sequences, where chromosome morphology varied in these components in terms of quantity and distribution. The 18S rDNA loci coincided with active NORs and C-banding patterns. We suggest that a combination of Robertsonian rearrangements and/or multiple common tandem fusions involving the same chromosomes contributed to the formation of this karyotype/karyomorphs. The results are the first step towards a better understanding of chromosomal reorganization and evolution within the genus Gonatoxia. Low chromosome number, together with the incidence of chromosomal polymorphism that is higher in G. helleri than previously reported in bush-crickets, implies that this species can be a valuable new model for cytogenetic and speciation studies. Our findings suggest that chromosomal translocations lead to diversification and speciation in this species and could be the driving force of adaptive radiation.

中文翻译：

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丛林蟋蟀 Gonatoxia helleri Hemp 中的快速染色体进化，2016 年（直翅目，Phaneropterinae）。

Gonatoxia helleri Hemp, 2016 是 Gonatoxia Karsch 属最广泛的丛林蟋蟀之一，1889 年在东非。这种具有七个大染色体 (2n♂ = 7) 的物种与 Gonatoxia 属的其他代表的显着不同之处在于其染色体数量减少、不对称核型，包括在 tettigoniids 中很少发现的核型，以及减数分裂过程中的不规则性。为了更好地了解这种特殊核型的起源，使用经典技术，如 C 显带、银浸渍、荧光染料双染色和荧光原位杂交 (FISH) 技术与 18S rDNA 研究了来自四个种群/地区的 29 个标本的染色体(TTAG)n 端粒探针。FISH 显示了许多 18S rDNA 位点以及间质端粒序列，其中染色体形态在这些成分中的数量和分布各不相同。18S rDNA 基因座与活性 NOR 和 C 带模式一致。我们建议罗伯逊重排和/或涉及相同染色体的多个常见串联融合的组合促成了这种核型/核型的形成。结果是更好地了解促性腺激素属内染色体重组和进化的第一步。低染色体数，以及 G. helleri 中染色体多态性的发生率高于以前在灌木蟋蟀中报道的发生率，这意味着该物种可以成为细胞遗传学和物种形成研究的有价值的新模型。