Mirolydidae, a new family of Jurassic pamphilioid sawfly (Hymenoptera) highlighting mosaic evolution of lower Hymenoptera

Mei Wang, Alexandr P. Rasnitsyn, ZhongqiYang, Chungkun Shih, Hongbin Wang &Dong Ren

We describe Pamphilioidea: Mirolydidae Wang, Rasnitsyn et Ren, fam. n., containing Mirolyda hirta Wang, Rasnitsyn et Ren, gen. et sp. n., from the late Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China. The new taxon is characterized by unique forewing venation with the presence of forewing SC, 1-RS almost as long as 1-M, M+Cu straight, 2rrs strongly reclival, and antenna with homonomous flagellum, revealing new and important details in antennal evolutionary transformations. Thus, M. hirta with a combination of primitive and more derived characters highlights its transitional state in the Pamphilioidea and complex mosaic evolution within Pamphilioidea in the late Middle Jurassic. The body of this species is densely covered with thin and long setae, suggesting its possible habit of visiting gymnosperm reproductive organs for pollen feeding and/or pollination during the late Middle Jurassic, much earlier than the appearance of angiosperm flowers.

我们描述了扁叶峰总科Pamphilioidea，其中新科Mirolydidae包括来了来自中国内蒙古道虎沟地区的晚中侏罗九龙山组的新属种Mirolyda hirta。新的分类群的鉴别特征为前翅存在Sc脉，1-Rs与1-M等长，M+Cu脉直，2r-rs脉强烈倾斜，触角各鞭节相同。该触角在触角进化转变方面展现了新的且重要的细节。因此，结合了原始及更多衍生特征的M. hirta强调在中三叠纪时期的扁叶峰总科及扁叶峰在总科内复合镶嵌演变中的过渡阶段。该种的身体密布有细且长的刚毛，这表明在晚中三叠纪及裸子植物花出现之前更早时期，这种习性可能是为了取食裸子植物对应器官的花粉或者为了授粉。