Re-description of the sperm morphology of Dalbulus maidis (Hemiptera: Cicadellidae: Deltocephalinae)

Abstract

The corn leafhopper, Dalbulus maidis, which is one of the most important vectors of maize diseases, had the morphology of its spermatozoa described more than 40 years ago. However, the description is imprecise, requiring certain rectifications. Hence, we re-describe the sperm morphology of this species using light microscopy and transmission electron microscopy. Their spermatozoa measured from 118.1 to 128.5 μm in length, this value being about three times smaller than what was previously described. The head region is formed by a small acrosome and the nucleus. The acrosome is paracrystalline and has the bifurcated base that is docked in two cavities on one side of the anterior region of the nucleus. The nucleus, which is linear and thin, measured from 19.3 to 22.9 μm in length, and exhibited homogeneously compact chromatin. In cross-section, it has a thumbtack shape, except in the anterior and posterior regions, where it is oval. The flagellum consists of an axoneme with 9 + 9 + 2 microtubules, two similar mitochondrial derivatives, two accessory bodies each associated with a small sub-ellipsoidal structure, and a ‘center-flagellar material’. In all the spermatozoa observed, the final portion of the flagellum was branched into four filaments. Some of these morphological features are now being re-described, while others have been observed for the first time in the Cicadellidae family, as the center-flagellar material.