Echinus esculentus is host to 2 species of Syndesmis. One of these, S. rubida sp. nov., is typically reddish, completely ciliated externally, has testes that extend from the intestine nearly to the lateral margins of the body, and has a short penis stylet that protrudes into the lumen of the male antrum. The other species, S. albida sp. nov., is pale pink or nearly white, lacks ciliation on the dorsal surface except near the anterior end, has testes concentrated close to the lateral margins of the body, and has an exceptionally long penis stylet. The distal portion of the stylet does not protrude into the male antrum. It lies within a cylindrical structure that has two sheaths of muscle. The outer sheath is continuous with the muscular sheath of the male antrum. The slightly spiral form of the proximal portion of the vagina of S. albida, and the relatively long, sclerotized distal portion, which has many kinks, are other features that separate this species from S. rubida. |
