Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP, Brazil.
Department of Paleobiology, NMNH, Smithsonian Institution, P.O. Box 37012 MRC 121, Washington, DC, 20013-7012, USA.
Cladistics. 2020 Aug;36(4):413-423. doi: 10.1111/cla.12413. Epub 2020 Mar 29.
The first two fossil species of the canthyloscelid genus Synneuron are described based on compression wings. Synneuron eomontana sp. nov. is described from the Middle Eocene Coal Creek Member of the Kishenehn Formation, in the USA, and Synneuron jelli sp. nov. is described from the Lower Cretaceous Koonwarra Fossil Bed of the Korumburra Group, in Australia. The wings are illustrated and compared to the extant species of the genus, to species of the three other recent genera of Canthyloscelidae and to an anisopodid. A phylogenetic analysis of the relationships between the species of Synneuron was performed. The Eocene fossil S. eomontana appears as sister of the pair of recent Holarctic species of the genus, while the Australian Cretaceous species S. jelli is sister of the clade with the species of Synneuron of the northern hemisphere. The sister group of Synneuron is the canthyloscelid clade (Hyperoscelis + Canthyloscelis), for which a middle Jurassic fossil is known. At the early Cretaceous, Gondwana was already separated from Laurasia and the disjunction between the species of Synneuron in Australia and the northern hemisphere clade of the genus suggest a true pangeic origin for the genus. The biology of the canthyloscelid larvae is shaped by its trophic specialization-xylosaprophagous. This suggests that the transition from the Pangean Jurassic gymnosperm-dominated forests to the late Cretaceous angiosperm-dominated forests may be related to the low recent diversity of Synneuron or of the canthyloscelids in the world-and maybe to the extinction of the genus in the southern hemisphere. This major turnover of the vegetation type along the Cretaceous may be also somehow related to the complete extinction of other groups of flies strictly associated with gymnosperms, as may be the case of the lower brachyceran family Zhangsolvidae. This speculation needs additional corroboration from other groups, that will become available with the combination of systematics, paleontology and biogeographical information of different early Cretaceous clades.
基于压缩翅片描述了两个Canthyloscelid 属的 Synneuron 化石种。描述了来自美国中始新世 Coal Creek 成员 Kishenehn 地层的新型 Synneuron eomontana sp. nov. 和来自澳大利亚下白垩纪 Koonwarra 化石床的新型 Synneuron jelli sp. nov.。翅片被图示并与该属的现存种、其他三个最近的 Canthyloscelidae 属的种以及一个 Anisopodidae 进行了比较。对 Synneuron 种之间的关系进行了系统发育分析。始新世化石 S. eomontana 与该属的一对现生北极种关系密切，而澳大利亚白垩纪种 S. jelli 与北半球的 Synneuron 种的分支关系密切。Synneuron 的姐妹群是 Canthyloscelid 分支（Hyperoscelis + Canthyloscelis），已知其有一个中侏罗世化石。在早白垩世，冈瓦纳大陆已经与劳亚古陆分离，而澳大利亚的 Synneuron 种和北半球属的分支之间的分离表明该属具有真正的泛古地理起源。Canthyloscelid 幼虫的生物学受其营养特化-xylosaprophagous 的影响。这表明，从泛古纪侏罗纪以裸子植物为主的森林到晚白垩纪以被子植物为主的森林的转变可能与 Synneuron 或世界上 Canthyloscelid 属的低现代多样性有关，也可能与该属在南半球的灭绝有关。随着系统学、古生物学和不同早白垩世分支的生物地理信息的结合，这种植被类型的重大转变可能与严格与裸子植物相关的其他蝇类群的完全灭绝有关，就像张索维德科（Zhangsolvidae）这样的低等双翅目科的情况一样。这种推测需要从其他群体获得额外的证实，这将随着不同早白垩世分支的系统学、古生物学和生物地理信息的结合而成为可能。
