Abstract. Riethia Kieffer, a genus of the non-biting midge subfamily Chironominae (Diptera: Chironomidae) is distributed in Australia, New Zealand, New Caledonia and South America. This austral distribution could be due to earth history (vicariance) or from Southern Hemisphere dispersal(s). We obtained samples from each area, most intensively from throughout Australia. We included putative sister genus Pseudochironomus Malloch, many genera from tribe Tanytarsini, enigmatic taxa in Chironomini and conventional outgroups from other subfamilies. We assembled a multilocus molecular dataset for four genetic regions from 107 individuals to reconstruct the first dated molecular phylogeny for the group. Four terminal clusters corresponded to unreared (thus unassociated) larvae. Monophyly was supported for ‘core’ Riethia, Pseudochironomus, putative tribe Pseudochironomini, tribe Tanytarsini (including enigmatic Nandeva Wiedenbrug, Reiss & Fittkau) and subfamily Chironominae. All species are monophyletic except for R. cinctipes Freeman, which includes R. neocaledonica Cranston. Riethia zeylandica Freeman, previously thought to be widespread in eastern Australia, now is a New Zealand endemic with Australian specimens allocated now to several regionally restricted species. The origin of Riethia was at 60.6 Ma (‘core’) or 52.1 Ma depending on the relationship of two South American species. Both dates are before the break-up of South America and Australia. Diversification within crown group Riethia started before the Cretaceous–Paleogene boundary, with subsequent separation at 52 Ma of an Australian ‘clade I’ from its sister ‘clade II’, which comprises Australian, New Zealand and New Caledonian species. Inferred dates for species origins of New Caledonia and New Zealand taxa imply transoceanic dispersals from eastern Australia. Western Australian species diverged during the mid to late Miocene from their eastern Australian sister taxa. This correlates with the onset of drying of Australia and the separation of mesic east from west by the formation of an arid proto-Nullarbor. Taken together, the inferred tempo of diversification in the group included both older ages reflecting earth history, yet with suggested recent intra-Pacific separations due to transoceanic dispersals.

中文翻译：

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Riethia如何“冈瓦纳”？分子系统发育学阐明了南太平洋摇蚊亚科（双翅目）多样化的模式和节奏

摘要。Riethia Kieffer 是不咬人摇蚊亚科摇蚊亚科（双翅目：摇蚊科）的一个属，分布于澳大利亚、新西兰、新喀里多尼亚和南美洲。这种南方分布可能是由于地球历史（替代）或来自南半球的扩散。我们从每个地区获取样本，最密集的是来自整个澳大利亚。我们包括推定的姐妹属 Pseudochironomus Malloch、Tanytarsini 部落的许多属、摇蚊中的神秘分类群和其他亚科的常规外群。我们为来自 107 个个体的四个遗传区域组装了一个多位点分子数据集，以重建该组的第一个过时的分子系统发育。四个终端簇对应于未饲养（因此未关联）的幼虫。Monophyly 支持“核心” Riethia、Pseudochironomus、假定的部落 Pseudochironomini、部落 Tanytarsini（包括神秘的 Nandeva Wiedenbrug、Reiss & Fittkau）和亚科 Chironominae。除了包括 R. neocaledonica Cranston 的 R. cinctipes Freeman 外，所有物种都是单系的。Riethia zeylandica Freeman，以前被认为在澳大利亚东部很普遍，现在是新西兰的地方性物种，澳大利亚的标本现在分配给了几个区域限制物种。 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Riethia 起源于 60.6 Ma（“核心”）或 52.1 Ma，具体取决于两个南美物种的关系。这两个日期都在南美洲和澳大利亚解体之前。冠群 Riethia 内的多样化在白垩纪 - 古近纪边界之前开始，随后在 52 Ma 时将澳大利亚“进化枝 I”与其姐妹“进化枝 II”分离，后者包括澳大利亚、新西兰和新喀里多尼亚物种。新喀里多尼亚和新西兰分类群物种起源的推断日期意味着来自澳大利亚东部的跨洋扩散。西澳大利亚物种在中新世中期至晚期与澳大利亚东部的姊妹类群发生分化。这与澳大利亚开始干燥以及通过形成干旱的原始 Nullarbor 将中西东与西分离有关。综上所述，该组中推断的多样化速度包括反映地球历史的较旧时代，但也表明最近由于跨洋扩散而导致太平洋内分离。西澳大利亚物种在中新世中期至晚期与澳大利亚东部的姊妹类群发生分化。这与澳大利亚开始干燥以及通过形成干旱的原始 Nullarbor 将中西东与西分离有关。综上所述，该组中推断的多样化速度包括反映地球历史的较旧时代，但也表明最近由于跨洋扩散而导致太平洋内分离。西澳大利亚物种在中新世中期至晚期与澳大利亚东部的姊妹类群发生分化。这与澳大利亚开始干燥以及通过形成干旱的原始 Nullarbor 将中西东与西分离有关。综上所述，该组中推断的多样化速度包括反映地球历史的较旧时代，但也表明最近由于跨洋扩散而导致太平洋内分离。