Data from: Across the Indian Ocean: a remarkable example of trans-oceanic dispersal in an austral mygalomorph spider

The Migidae are a family of austral trapdoor spiders known to show a highly restricted and disjunct distribution pattern. Here, we aim to investigate the phylogeny and historical biogeography of the group, which was previously thought to be vicariant in origin, and examine the biogeographic origins of the genus Moggridgea using a dated multi-gene phylogeny. Moggridgea specimens were sampled from southern Australia and Africa, and Bertmainus was sampled from Western Australia. Sanger sequencing methods were used to generate a robust six marker molecular dataset consisting of the nuclear genes 18S rRNA, 28S rRNA, ITS rRNA, XPNPEP3 and H3 and the mitochondrial gene COI. Bayesian and Maximum Likelihood methods were used to analyse the dataset, and the key dispersal nodes were dated using BEAST. Based on our data, we demonstrate that Moggridgea rainbowi from Kangaroo Island, Australia is a valid member of the otherwise African genus Moggridgea. Molecular clock dating analyses show that the inter-specific divergence of M. rainbowi from African congeners is between 2.27–16.02 million years ago (Mya). This divergence date significantly post-dates the separation of Africa from Gondwana (95 Mya) and therefore does not support a vicariant origin for Australian Moggridgea. It also pre-dates human colonisation of Kangaroo Island, a result which is further supported by the intra-specific divergence date of 1.10–6.39 Mya between separate populations on Kangaroo Island. These analyses provide strong support for the hypothesis that Moggridgea colonised Australia via long-distance trans-Indian Ocean dispersal, representing the first such documented case in a mygalomorph spider.Migidae蛛科（Migidae）是一类南半球特有的陷阱蜘蛛类群，其分布格局呈现高度局限且间断的特征。本研究旨在探究该类群的系统发育与历史生物地理学特性——此前学界曾推测其起源于隔离分化事件——并通过定年多基因系统发育树分析Moggridgea属的生物地理起源。研究采样了产自澳大利亚南部与非洲的Moggridgea属标本，以及产自西澳大利亚的Bertmainus属标本。采用桑格测序（Sanger sequencing）技术构建了一套稳健的六标记分子数据集，涵盖核基因18S rRNA、28S rRNA、ITS rRNA、XPNPEP3、H3以及线粒体基因COI。分别采用贝叶斯法与最大似然法对该数据集开展分析，并借助BEAST软件对关键扩散节点进行分子定年。基于本研究的数据，我们证实产自澳大利亚袋鼠岛的Moggridgea rainbowi是原本仅分布于非洲的Moggridgea属的有效成员。分子钟定年分析显示，该物种与非洲同属物种的种间分化时间介于227万至1602万年前（Mya）。这一分化时间显著晚于非洲与冈瓦纳大陆分离的时间（约9500万年前），因此不支持澳大利亚Moggridgea属起源于隔离分化事件的假说。同时，该分化时间早于人类登陆袋鼠岛的时间，这一结论亦得到袋鼠岛不同种群间110万至639万年前的种内分化时间数据的进一步佐证。本研究结果为"Moggridgea属通过跨印度洋长距离扩散定殖澳大利亚"这一假说提供了强有力的支持，这也是原蛛亚目蜘蛛（mygalomorph spider）中首例被证实的此类扩散案例。