Synchronous Penis Shedding in the Rough Periwinkle,Littorina Arcana

Abstract
Penis size and morphology of an oviparous species of rough winkleLittorina arcanaHannaford Ellis (Gastropoda: Prosobranchia) was studied at Robin Hoods Bay on the English east coast. Monthly collections were made over a two year period from August 1987 to August 1989 and again from May to December 1993. Number of penial glands was recorded and a six point scale was used to quantify penis maturity. Results indicate that maleL. arcanashed their penes in summer and regenerate a new one during the following 12–20 weeks. MaleL. arcanain captivity shed penes in July but not in November. The significance of penis shedding and the differences in reproductive seasonality betweenL. arcanaand its ovoviviparous sibling speciesL. saxatilisis discussed.