Gonochoric representatives of Littorinidae have a reproductive system organized with transit organs that connects the testicle with a penis specialized for internal fertilization. However, malformations at this level can produce, like triphallia (presence of triple penis). This description corresponds to one case of triphallia found in Echinolittorina peruviana (Lamarck, 1822) inhabitant of the South Pacific coasts. The macro and microscopic analysis reveals that every penis is an independent appendix whose individual morphology is similar to that in normal individuals, characterized by a non pigmented conic penis associated with a mammilliform gland located at the base of the right ocular tentacle. The cervical sperm groove lined by a simple ciliated and secretory columnar epithelium, runs along the neck of the animal, is subdivided into the base of each penis forming the penile seminal groove in each of them, and ascends dorsally from the base to the tip. The other organs that make up the reproductive system have a normal organization (no duplication or triplets), and the testicle organized in acini contains all the cell types of the male germ line. Although the cause of this condition is still unknown, might be associated with genetic causes and not of environmental kind.
CASTILLO, V. M. & BROWN, D. I. One case of Triphallia in the Marine Snail Echinolittorina peruviana (Caenogastropoda: Littorinidae). Int. J. Morphol., 30(3):791-796, 2012.