Histomorphology of the female pallial gonoduct in Dicathais orbita (Neogastropoda, Muricidae): sperm passage, fertilization, and sperm storage potential

The current investigation provides the first histomorphological description of the female pallial gonoduct in the muricid mollusc Dicathais orbita, and of sperm passage in the subfamily Rapaninae. Gonoduct anatomy, musculature, and sperm distribution were documented over the annual reproductive cycle to confirm the site of fertilization in members of the Muricidae, provide evidence for sperm storage, and allow subfamilial comparisons in reproductive anatomy and strategies. This approach revealed morphological plasticity of the ingesting gland in D. orbita, which has implications for the use of gonoduct character traits in taxonomic studies of the Muricidae. Other features of subfamilial diagnostic interest, including the ventral channel and both albumen and capsule glands, are highlighted to show common character traits between the Rapaninae, Ocenebrinae, and Muricinae. Conversely, distinct differences in posterior capsule and pedal gland morphology may aid subfamilial classification of Rapaninae species in future revisions of the Muricidae. Histomorphology coupled with sperm distribution revealed the passage of sperm and identified the dorsal albumen gland as the site of fertilization. Temporally replicated sampling indicated the potential for sperm storage for ≤10 months within the seminal receptacles in D. orbita. Sperm ingestion provides a possible mechanism for sexual selection, suggesting further investigation into sperm storage is warranted in the Muricidae.