Data from: Cave Stedocys spitting spiders illuminate the history of the Himalayas and Southeast Asia

Stedocys spitting spiders (Araneae: Scytodidae) inhabit subterranean environments and have poor dispersal abilities. The Cenozoic Indian–Eurasian collision affected the regional biota of this genus, which occurs in parts of Indochina. Phylogeographical pattern of Stedocys based on multigene DNA sequence datasets reveals how tectonic history drove four biological splits. The first split dates to the late Paleocene–Eocene and involves the Truong Son Mountain Range and Mekong River. The other splits associate with the Eocene–Oligocene transition, including the Tonkin (Beibu) Gulf, the Ma River, and the Red River. These events indicate four early uplifts of the Himalayas and Tibetan Plateau. Our results cannot reject the hypothesis that uplifting of the Himalayas and Tibetan Plateau region due to crustal thickening and the lateral extrusion of Indochina occurred synchronously during the Paleocene–Oligocene transition in reaction to the Indian–Eurasian collision. Species of Stedocys cluster into groups I and II. Their evolution involves one dispersal and four vicariance events, which formed the following five Indochinese clades: Hainan clade (I-1); western Yunnan and central Laos clade (I-2); central Vietnam clade (I-3); northern Vietnam and southwestern China clade (I-4); and Thailand clade (II-1). The lateral extrusion of Indochina is the driver of these events. The drifting of Hainan Island to its present location owes to its southeastern movement from continental Vietnam and Guangxi, China around the Eocene–Oligocene boundary. This biogeographical pattern highlights the significant role geography plays in shaping evolutionary history in southeastern Asia. It also illuminates the how the timing of geological events drives the distributions of species.

喷液蛛属（Stedocys）蜘蛛（蜘蛛目：花皮蛛科）栖息于地下生境，扩散能力较弱。该属分布于中南半岛部分区域，新生代印度-欧亚板块碰撞对其区域生物区系造成了深刻影响。基于多基因DNA序列数据集解析的Stedocys系统地理格局，揭示了构造历史如何驱动了四次生物分化事件：第一次分化事件发生于古新世晚期-始新世，涉及长山山脉与湄公河；其余三次分化事件与始新世-渐新世过渡期相关，涵盖北部湾（东京湾）、马江与红河。上述事件指示喜马拉雅与青藏高原曾发生四次早期隆升。本研究结果无法驳斥如下假说：受印度-欧亚板块碰撞驱动，地壳增厚与中南半岛侧向挤出所引发的喜马拉雅及青藏高原区域隆升，于古新世-渐新世过渡期同步发生。Stedocys属物种可划分为I、II两个类群，其演化历程包含一次扩散事件与四次隔离分化事件，由此形成以下五个中南支演化支：海南岛演化支（I-1）、滇西与老挝中部演化支（I-2）、越南中部演化支（I-3）、越南北部与中国西南演化支（I-4）以及泰国演化支（II-1）。中南半岛侧向挤出是上述演化事件的核心驱动因素。海南岛现今的分布格局源于其在始新世-渐新世交界期，从越南大陆与中国广西地区向东南漂移而来。该生物地理格局凸显了地理因素在塑造东南亚区域演化历史中的关键作用，同时阐明了地质事件的发生时序如何主导物种的分布格局。