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.

曼吉蛛科（Migidae）是一类分布于南半球的陷阱蜘蛛，其分布范围极狭窄且呈间断分布格局。本研究旨在探究该类群的系统发育与历史生物地理学特征——此前该类群被认为起源于异域分化事件——并基于定年的多基因系统发育分析，检验莫格蛛属（Moggridgea）的生物地理起源。研究采集了采自澳大利亚南部、非洲的莫格蛛属标本，以及采自西澳大利亚的伯特曼蛛属（Bertmainus）标本。采用桑格（Sanger）测序法构建了一套稳健的六标记分子数据集，包含核基因18S rRNA、28S rRNA、ITS rRNA、XPNPEP3、H3以及线粒体基因COI。分别采用贝叶斯（Bayesian）推断法与最大似然（Maximum Likelihood）法对该数据集进行分析，并使用BEAST软件对关键扩散节点进行定年。基于本研究的数据，我们证实采自澳大利亚袋鼠岛的彩虹莫格蛛（Moggridgea rainbowi）是原本仅分布于非洲的莫格蛛属的有效成员。分子钟定年分析显示，彩虹莫格蛛与非洲同属物种的种间分化时间介于227万至1602万年前（Mya）。该分化时间显著晚于非洲与冈瓦纳大陆的分离时间（95 Mya），因此不支持澳大利亚莫格蛛类群起源于异域分化的假说；同时该时间也早于人类定居袋鼠岛的时间，这一结论得到了袋鼠岛不同种群间110万至639万年前的种内分化时间数据的进一步验证。本研究的分析结果为‘莫格蛛属通过跨印度洋长距离扩散殖民澳大利亚’这一假说提供了强有力的支持，这也是猛蛛亚目蜘蛛（mygalomorph spider）中首个被记录的此类扩散案例。