Date Published: July 19, 2017
Publisher: Public Library of Science
Author(s): Lea F. Schubert, Stephanie Krüger, Gerald B. Moritz, Veit Schubert, Suresh Yenugu.
Based on advanced light and electron microscopy, we describe the male reproductive system and sperm development of Limodromus assimilis. The genital tract consists of pairs of uni-follicular testes, spermatic ducts with diverticula regions, seminal vesicles, accessory glands, an unpaired ejaculatory duct and an aedeagus containing an internal sac equipped with sclerotic scales. Based on their morphology, we draw conclusions about their functions. After spermatogenesis within the follicle, the spermatozoa become released from the sperm cysts. The single spermatozoa move into the diverticula of the vasa deferentia I. Here, they become attached to central rods (spermatostyles), forming secondary conjugates (spermiozeugmata). The coordinated flagella movement of the conjugates possibly improves sperm velocity. Using super-resolution microscopy, we identified highly condensed reticulate chromatin in the lancet-shaped spermatozoa heads and the mitochondrial derivates of the flagella, likely formed by genomic and mitochondrial DNA, respectively. The results show, for the first time, sperm bundle formation in a Platynini species mainly corresponding to that found in Pterostichini species.
Insect reproductive systems show large morphological variability. Similarly, their spermatozoa may vary strongly in shape and size [1, 2]. In addition to single flagellate and multi-flagellate spermatozoa, others without flagella appear . Some species form conjugates of spermatozoa, first identified by Gilson . These were described in orders such as Odonata , Hymenoptera , Orthoptera  and Coleoptera .