In the present study, we describe the sperm morphology of 11 species of Elateriformia (9 elaterids, 1 lampyrid and 1 buprestid) using transmission electron microscopy. All species exhibited sperm that is not usually observed in insects in general. The most highlighted features are the displacement of the nucleus running parallel to the flagellar components, hitherto observed only in coccinellid and carabid beetles, and the presence of thin and dense structures along the nucleus, probably derived from the centriole adjunct, a feature that is so far exclusive to these insects. The other structures are a typical axoneme for insects with 9 + 9 + 2 microtubules, in a position diametrically opposite relative to the nucleus, two slender, symmetrical mitochondrial derivatives and a pair of discrete accessory bodies. This arrangement provides a bilaterally symmetrical flagellum, which favourably influences sperm hydrodynamics, as will be discussed. The occurrence of this unusual structural arrangement in the sperm of species from superfamilies that are phylogenetically as distant as Elateroidea and Buprestoidea support the monophyly of the infraorder Elateriformia, as proposed by some previous molecular studies.

在本研究中，我们使用透射电子显微镜描述了11种Elateriformia（9个elaterids，1个Lampyridid和1个buprestid）的精子形态。所有物种都表现出通常在昆虫中通常不观察到的精子。最突出的特征是与鞭毛组件平行的核移位，迄今为止仅在球虫和甲壳虫中观察到，并且沿核存在细而密的结构，可能源自中心粒附属物，如此特征这些昆虫所独有。其他结构是具有9 + 9 + 2个微管的昆虫的典型轴突，位于相对于细胞核相对的位置，两个细长的对称线粒体衍生物和一对离散的附属体。如将要讨论的，这种布置提供了双向对称的鞭毛，其有利地影响了精子的流体动力学。如一些先前的分子研究所提出的那样，系统发育上与Elateroidea和Buprestoidea一样遥远的超家族物种的精子中这种不寻常的结构排列的出现，支持了地下Elateriformia的单性。