A new xyelotomid (Hymenoptera) from the Middle Jurassic of China displaying enigmatic venational asymmetry.
A new xyelotomid (Hymenoptera) from the Middle Jurassic of China displaying enigmatic venational asymmetry.
复制标题
中国中侏罗世的一种新木翅目（膜翅目）表现出神秘的脉系不对称性
DOI：
10.1186/s12862-016-0730-0
复制
发表时间：
2016-08-02
影响因子：
3.4
通讯作者：
Ren D
中科院分区：
文献类型：
--
作者：
Gao T;Shih C;Engel MS;Ren D
有翼类昆虫的左翼和右翼通常具有对称的静脉。为了研究化石昆虫的分类学和系统发育，脉系模式通常与保存的身体特征一起用作诊断特征。现存昆虫中存在一些不对称脉络的例子，但只有少数具有不对称翅膀的昆虫化石被报道，其中先前描述的膜翅目木翅目 Xyelocerus diaphanous 在左前翅中显示出不寻常的小脉纹 Rs 细胞，但在右前翅中却没有。在此，我们报道了锯蝇科的一种新锯蝇，Aetotoma aninomorpha gen。等11月，来自中国中侏罗世晚期，前翅有一个简单的Sc，后翅有两个分支。此外，新标本表现出神秘的静脉不对称性。在右前翅中，横脉 2r-rs 形成一个环，然后分叉成 2 个长分支，达到 Rs，而左前翅的 2r-rs 分叉成 2 个短分支，达到 Rs，这与典型化石和现存锯蝇中的线性 2r-rs 形成鲜明对比。从锯蝇化石中发现的这种罕见的不对称脉络，让人们得以了解中侏罗世晚期昆虫的脉络变异性和不稳定性的早期发生，或者可能的异常发育。
Pterygota insects typically have symmetric veins in left and right wings. For studying taxonomy and phylogeny of fossil insects, venational patterns are commonly used as diagnostic characters, in conjunction with preserved body characters. Some examples of asymmetrical venation are known among extant insects, but only a few fossil insects with asymmetric wings have been reported, among which a previously described xyelotomid of Hymenoptera, Xyelocerus diaphanous, displays an unusual, small cell of vein Rs in the left forewing, but not in the right. Herein we report a new sawfly of the family Xyelotomidae, Aethotoma aninomorpha gen. et sp. nov., from the late Middle Jurassic of China having a simple Sc in the forewing and Sc with two branches in the hind wing. In additional, the new specimen exhibits an enigmatic venational asymmetry. In the right forewing, crossvein 2r-rs of forms a loop, then forks into 2 long branches reaching Rs, while 2r-rs of the left forewing forks into 2 short branches reaching Rs, in contrast to a linear 2r-rs in typical fossil and extant sawflies. Such rare asymmetrical venation found from fossil sawflies provides a glance at early occurrences of venational variability and instability, or possibly aberrational development, for insects in the late Middle Jurassic.