The coevolution between sperm length and size of the female sperm-storage organs is described for the first time within Heteroptera. The long sperm of the measurer bug Hydrometra stagnorum is characterized by the unusually long acrosome with its anterior region helically arranged, and by a very short nucleus. The sperm flagellum has a 9 + 9+2 conventional axoneme and crystallized mitochondrial derivatives. The female spermatheca consists of an extraordinarily long spermathecal duct ending with an apical spermathecal bulb into which flows also the secretions of a relatively short spermathecal gland. Both spermathecal duct and gland have a thin epithelium lined by a cuticle, beneath which a complex of secretory and duct forming cells are present. The secretions of these two structures flow into the apical spermathecal bulb. A thick layer of muscle fibers surrounds the epithelium. These results confirm the opinion that the dimensions of the female reproductive sperm-storage organs are able to drive the sperm morphology.

在异翅目中首次描述了精子长度和雌性精子储存器官大小之间的共同进化。测量虫Hydrometra stagnorum的长精子其特征是具有异常长的顶体，其前部呈螺旋状排列，并且具有非常短的核。精子鞭毛具有 9+9+2 的常规轴丝和结晶的线粒体衍生物。雌性受精囊由一根极长的受精囊管组成，其末端是一个顶端的受精囊球，其中也流入一个相对较短的受精囊腺的分泌物。受精管和腺体都有一层薄薄的上皮，内衬有角质层，其下方存在分泌细胞和管形成细胞的复合体。这两种结构的分泌物流入顶端的受精囊球。一层厚厚的肌肉纤维围绕着上皮。这些结果证实了女性生殖精子储存器官的尺寸能够驱动精子形态的观点。