The spitting spider Scytodes fusca is a species complex well known for its unusual hunting technique which involves spitting a venomous sticky silken substance over its prey. Previous studies supposed that S. fusca was native to Central and South America but had expanded to the tropics of almost every continent. We aimed to test the hypothesis of a Neotropical origin for this spider followed by a secondary dispersal to other regions, and to discuss how population expansion occurring in the tropics was driven. We investigated the population structure and spatiotemporal biogeography of the species complex through the culmination of 22 years of comprehensive global sampling using the mitochondrial and nuclear loci (COI, 16S, 18S, 28S, H3 and ITS2). The S. fusca species complex is divided into two clades. One clade comprises the haplotypes from Australasian regions and a haplotype from Baja Peninsula, Mexico. The other is composed of the haplotypes from all analyzed regions including Asia, Australia, the Americas and Madagascar. Populations from the Americas and Madagascar exhibit a lower genetic diversity compared with the Australasian population, and both have different population demographic histories. The initial divergence within the species complex started during the early Miocene. Diversifications of both clades occurred during the late Miocene. One haplotype was recently and widely dispersed into Southeast Asia, South Asia, Australia, the Americas and Madagascar. Our results elucidate the history of the global spread of the S. fusca species complex, suggesting a Malay Archipelago origin, two expansion routes and its multiple dispersals into the Americas. These stem from a common native source population, as well as from Australia, Fiji, French Polynesia or Turks and Caicos bridgeheads. Our data support the view that the expansion of the S. fusca species complex from Australasia to America and Madagascar was facilitated by long-distance jump dispersal events.

中文翻译：

---

由多次长距离传播形成的孤独社会热带吐痰蜘蛛的全球扩张

吐痰蜘蛛Scytodes fusca是一个复杂的物种，以其不寻常的狩猎技术而闻名，这种技术包括在猎物身上吐出有毒的粘性丝质物质。之前的研究假设S. fusca原产于中美洲和南美洲，但已经扩展到几乎每个大陆的热带地区。我们的目的是检验这种蜘蛛起源于新热带并随后二次扩散到其他地区的假设，并讨论热带地区发生的种群扩张是如何驱动的。我们通过使用线粒体和核位点（ COI、16S、18S、28S、H3）进行了 22 年的全面全球采样，调查了该物种复合体的种群结构和时空生物地理学和 ITS2)。S. fusca物种复合体分为两个进化枝。一个进化枝包括来自澳大利亚地区的单倍型和来自墨西哥巴哈半岛的单倍型。另一个由来自所有分析区域的单倍型组成，包括亚洲、澳大利亚、美洲和马达加斯加。与澳大利亚人口相比，来自美洲和马达加斯加的人口表现出较低的遗传多样性，并且两者都有不同的人口统计历史。物种复合体内部的最初分化始于中新世早期。两个进化枝的多样化都发生在中新世晚期。一种单倍型最近广泛分布到东南亚、南亚、澳大利亚、美洲和马达加斯加。我们的结果阐明了全球传播的历史S. fusca物种复杂，表明起源于马来群岛、两条扩张路线及其多次扩散到美洲。这些源于共同的本地来源人口，以及来自澳大利亚、斐济、法属波利尼西亚或特克斯和凯科斯群岛的桥头堡。我们的数据支持这样一种观点，即长距离跳跃扩散事件促进了S. fusca物种复合体从大洋洲到美洲和马达加斯加的扩张。