First evidence of sperm remains on penis after mating in Opiliones (Opiliones: Gonyleptidae: Pachyloides thorellii)

Male harvestmen penial armature has a remarkable morphology; however, it is poorly known regarding its functions. We examined the male genitalia of virgin and mated males of the gonyleptid Pachyloides thorellii under Scanning Electron Microscope looking for evidence that the penis could remove sperm from the female ovipositor lumen during mating. Micrographs show sperm agglutinations over and within the microsetae fields in six out of the 12 mated males studied. For the mating experiments we used only virgin females, therefore the sperm found in the penis was in all cases their own sperm. This self-sperm removal could be the extraction of sperm excess in cooperation (or not) with the females. This is the first study to show for the Order Opiliones direct evidence that a male penis contains structures that can effectively remove sperm from the female ovipositor. Further behavioral and morphological studies are needed to confirm the conditions of occurrence and participation of each sex in sperm removal processes in this species.