Unveiling genital specializations in <i>Megascolex travancorensis</i> (Oligochaeta: Megascolecidae) through scanning electron microscopy

When an earthworm reaches reproductive age, its clitellum, also referred to as the genital collar, observably enlarges and becomes more glandular. Genital features in Megascolecidae, including male and female pores, papillae, grooves, and glandular thickenings, show species-specific patterns linked to reproduction, thereby serving as important characters in taxonomy and systematics. This work uses comprehensive scanning electron microscopy (SEM) images to investigate the male reproductive anatomy of Megascolex travancorensis Michaelsen, 1910. A slit-shaped male pore located on a raised genital papilla, paired prostatic ducts, a seminal groove, retracted penial setae, and eye-like genital marks on segment 18 are among the distinctive morphological features highlighted in the investigation. Fine-scale structural adaptations have been shown by SEM, which has also helped to classify accurately the genus Megascolex taxonomically and provide important information about reproductive morphology.