Morphological Investigation of the marine tubificid Clitellio arenarius (Annelida, Oligochaeta)
Sarsia
80(2): 159-171
Publication
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Light and scanning electron microscopy was carried out to reinvestigate the morphology of Clitellio arenarius (Annelida, Oligochaeta), the first marine oligochaete ever described. New morphological information about the spermathecae and the female and male genital ducts is provided. The paired spermathecae, which contain spermatozeugmata after copulation, each consists of a narrow duct and a voluminous ampulla. Close to the ampulla a muscle fibre surrounds the duct, forming a sphincter. The ampulla consists of two parts, one with a thin and the other with a thick wall. The two parts are separated by a thin diaphragm with a small orifice in the middle. The male genital ducts consist of paired sperm funnels, vasa deferentia and atria which terminate in penes. The vas deferens is composed of two parts, one thin-walled and the other thick-walled, both with cilia. The atrium, the glandular part ofthe male duct, is tubular, long and ciliated throughout. Specimens ofCliteliio arenarius from the west coast of Sweden and the south coast of England are compared. The only differences found are in the shape of the setae and the length of vas deferens; the worms from England have bifid setae and longer vasa deferentia, those from Sweden have single-pointed as well as a few bifid setae.
