Sperm ultrastructure of Pycnoderes incurvus (Hemiptera: Miridae)

Area of Science:

• * Zoology
• * Evolutionary Biology
• * Entomology

Background:

• * Sperm morphology is crucial for understanding sexual selection, phylogeny, and evolutionary history in animal groups.
• * Knowledge of sperm structure is limited in many insect taxa, particularly within the diverse order Hemiptera.
• * The Miridae family (plant bugs) has scarce published data on sperm morphology, with only three of 17 families studied.

Purpose of the Study:

• * To describe the sperm structure of Pycnoderes incurvus, a representative of the Miridae family.
• * To identify unique morphological characteristics of P. incurvus spermatozoa.
• * To contribute to the understanding of Heteroptera phylogeny and evolutionary relationships.

Main Methods:

• * Light microscopy and transmission electron microscopy were used to analyze Pycnoderes incurvus sperm.
• * Detailed examination of the spermatozoa, including acrosome, nucleus, centriole adjunct, and flagella.

Main Results:

• * Pycnoderes incurvus spermatozoa are long and slender, typical of insects.
• * A twisted anterior-most region of the sperm, specifically the acrosome, was observed, a novel finding for Heteroptera.
• * A unique, long, cylindrical centriole adjunct connects the nucleus to flagellar elements.
• * Flagella feature a 9+9+2 axoneme and two symmetrical mitochondrial derivatives with paracrystalline areas, considered Heteroptera synapomorphies.

Conclusions:

• * The unique sperm structures of P. incurvus provide valuable data for Miridae systematics.
• * The identified flagellar characteristics support the monophyly of Heteroptera.
• * This study highlights the importance of sperm morphology in elucidating insect evolutionary history.