Spermatophore morphology in the hermit crab families Paguridae and Parapaguridae (Paguroidea, Anomura, Decapoda)

The spermatophore morphology is described and illustrated for 11 species of pagurid hermit crab. All possess a typical tripartite, pedunculate spermat ophore characteristic of paguroid anomurans. In the majority of species an accessory ampulla is present at the base of the sperm-filled main ampulla o f the spermatophore. This accessory ampulla is attached to the peduncle of the spermatophore, or is incorporated into it, and may or may not contain a ny spermatozoa. The spermatophores of Pagurus chevreuxi, Solitariopagurus t uerkayi and Xylopagurus caledonicus lack an obvious accessory ampulla. Tran smission electron microscopy reveals that the wall and peduncle of the acce ssory ampullae of Pagurus bernhardus are identical in appearance to, and co ntinuous with, the same structures on the main ampullae. The stalk and sper matophore wall in both accessory and main ampullae in P. bernhardus are com posed of a homogeneous, finely grained matrix of moderate electron-density. Like the main ampullae, the accessory ampullae of P. bernhardus have a lat eral ridge present around their peripheral edge. Two species of the parapag urid hermit crab genus Sympagurus also possess spermatophores with accessor y ampullae adjacent to the main ampullae.