Dispersal is essential for terrestrial organisms living in disjunct habitats and constitutes a significant challenge for the evolution of wingless taxa. Springtails (Collembola), the sister-group of all insects (with dipluran), are reported since the Lower Devonian and thought to have originally been subterranean. The order Symphypleona is reported since the early Cretaceous with genera distributed on every continent, implying an ability to disperse over oceans although never reported in marine water contrary to other springtail orders. Despite being highly widespread, modern springtails are generally rarely reported in any kind of biotic association. Interestingly, the fossil record has provided occasional occurrences of Symphypleona attached by the antennae onto the bodies of larger arthropods. Here, we document the case of a ~16 Ma old fossil association: a winged termite and ant displaying not some, but 25 springtails attached or closely connected to the body. The collembola exhibit rare features for fossils, reflecting their courtship and phoretic behaviors. By observing the modes of attachment of springtails on different arthropods, the sex representation and ratios in springtail antennal anatomies in new and previously reported cases, we infer a likely mechanism for dispersal in Symphypleona. By revealing hidden evidence of modern springtail associations with other invertebrates such as ants and termites, new compelling assemblages of fossil springtails and the drastic increase of eusocial insects’ abundance over Cenozoic (ants/termites comprising more than the third of insects in Miocene amber), we stress that attachment with winged casts of ants and termites may have been a mechanism for the worldwide dispersal of this significant springtail lineage. Moreover, by comparing the general constraints applying to the other wingless soil-dwelling arthropods known to disperse through phoresy, we suggest biases in the collection and observation of phoretic Symphypleona related to their reflexive detachment and infer that this behavior continues today. The specific case of tree resin entrapment represents the (so far) only condition uncovering the actual dispersal mechanism of springtails - one of the oldest terrestrial arthropod lineages living today. Associations with soil-dwelling social insects over time would have been at the origin of this behavioural specialization.

中文翻译：

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化石琥珀揭示了社交昆虫对跳尾的长期扩散

分散对于生活在离散生境中的陆地生物至关重要，并且对无翅类群的进化构成重大挑战。自下泥盆纪以来，据报道所有昆虫（含双足纲）的姊妹组-跳尾（Collembola），最初被认为是地下的。据报道，自白垩纪早期以来，Symphypleona令的属分布在每个大陆上，这意味着它具有散布在海洋上的能力，尽管从未见过与其他跳尾顺序相反的在海水中的报道。尽管具有很高的流行性，但现代跳尾一般很少以任何一种生物关联的形式报道。有趣的是，化石记录偶尔会出现触角藻，通过触角附着在较大节肢动物的身上。这里，我们记录了一个〜16 Ma的古老化石协会的情况：有翅的白蚁和蚂蚁显示的不是一些，而是25个附着或紧密连接到身体的跳尾。collembola展示了化石的稀有特征，反映了它们的求爱和隐喻行为。通过观察在新的和先前报道的病例中在不同节肢动物上的凤尾鱼的附着模式，在凤尾鱼触角解剖学中的性别表示和比率，我们推断出在茎突藻中散布的可能机制。通过揭示与其他无脊椎动物（如蚂蚁和白蚁），新的引人注目的化石跳尾组合以及现代社会昆虫对新生代的丰富数量（蚂蚁/白蚁占中新世琥珀虫的三分之一以上）后隐藏的证据，我们强调，与有翼的蚂蚁和白蚁模型的附着可能是这种重要的跳尾谱系在世界范围内扩散的机制。此外，通过比较适用于已知通过电泳散布的其他无翅土居节肢动物的一般约束条件，我们建议收集和观察与他们的反射性脱离相关的幻觉Symphypleona偏见，并推断这种行为在今天仍在继续。树状树脂被困的特殊情况代表了（迄今为止）唯一的条件，该条件揭示了跳尾的实际扩散机制-当今生活的最古老的陆生节肢动物世系之一。随着时间的推移，与居住在土壤中的社交昆虫的联系将是这种行为专业化的起源。