Snails and slugs: materials
Stylommatophoran sperm cells are most easily obtained from the spermatophores that these hermaphroditic animals produce and transfer during mating. Therefore, adult, large-bodied snails and slugs were collected in several locations in the Dutch provinces of Zuid-Holland, Noord-Holland, and Flevoland during spring and early summer (when mating takes place) of 2014 and 2015. We collected animals that were found in copula, but also mature animals that may have recently mated and therefore contain fresh sperm in the spermatophore-receiving organ. All specimens were stored in 70% ethanol in the field. The animals were identified, dissected, and, when spermatophores were encountered, these were carefully removed and cut or broken lengthwise. The exposed halves were then dehydrated in an automated Leica EM CPD300 critical-point drier and affixed on stubs for scanning electron microscopy.