Functional morphology and evolution of the male secondary copulatory apparatus of the Anisoptera (insecta: Odonata)

Viac o knihe

This study meticulously reconstructs the functions and mechanical interactions of the secondary copulatory apparatus in Anisoptera, detailing potential evolutionary pathways. Unlike Zygoptera and Anisozygoptera, where the vesica spermalis is a single-segmented sperm-storage organ, Anisoptera features a four-segmented version. A key focus is the evolutionary implications of the secondary “penis” and sperm-syringe. The male dragonfly's secondary copulatory apparatus, located on the second and third abdominal segments, comprises sequential devices that support the female ovipositor, prepare for sperm-storage, leverage and insert the secondary “penis,” and transmit sperm to the female vagina. Each function involves coordinated actions of sclerites and muscles. The study describes various methods for filling the sperm-reservoir, highlighting a primitive, labor-intensive process reliant on the ligula and ovipositor. Evolutionary modifications, influenced by ovipositor reduction, led to more advanced filling and protection techniques. Additionally, the study examines auxiliary devices for emptying the sperm-reservoir, including two types of sperm-pumps in the distal segment that coordinate sperm-suction and ejection. A comparative analysis of different “glans” reveals diverse mechanisms for sperm displacement and intensification of the sperm-jet. The evolutionary stages of the glans, reflecting phylogenetic splits, are outlined, maki