合长足虻亚科是农林生态系统中重要的捕食性天敌昆虫。它们取食同翅目粉虱、木虱和介壳虫类等，对害虫起着一定的控制作用，是有用的天敌昆虫资源。但是截至目前，该亚科目前开展的研究均为区域性工作，相对于其他动物地理区系而言，东洋区尚有大量的种类有待发现和描述，该亚科各属间的系统发育关系至今缺少动物地理数据的支持，此外，多个广布属的属征及动物地理分布格局需要总结和分析。因此亟需展开合长足虻亚科的种类修订、属间系统发育分析和地理分布工作，实现对该亚科全面、准确的认识，为本类群世界性系统修订工作提供重要资料。. 本项目拟对我国合长足虻亚科昆虫的分类进行系统研究，揭示其多样性和分布格局，结合形态学数据和分子数据，并运用比较形态学和支序分类学的原理和方法，阐明各属之间的系统演化关系。研究结果对于揭示该亚科各属间的系统进化关系以及该类群多样性在生物防治上的应用研究均具有重要意义。

The Sympycninae flies can prey on mealworms, psyllids and scale bugs, and act as important predative natural enemy in agricultural and forestry ecosystems. Due to its systematic and economic importance, many international scientists focus on the taxonomy and ecology of Sympycninae. But by far, the ongoing study of the subfamily are regional work. Comparing with other faunae, no detailed revision work on this subfamily has been carried out in Oriental region, and also a great number of species are still undetermined and undescribed in this region. It's need to summary these general characters and analysis geographical distribution style for genera distributed worldwide. And the phylogenetic relationships between genera lacks of support from biogeographical data. . So based on the mentioned above, this research tends to study the systematics and biogeography of Sympycninae from China and surrounding area in order to reveal genera and species diversity and distribution patterns. Based on the morphological and molecular data, using methods of comparative morphology and cladistics, combined with biogeography, the relationships among genera will be clarified. The present project is very helpful for understanding the phylogeny of this subfamily and also for the utlization and conservation of its diversity.