South African populations of Littorina rudis

Littorina rudis was collected from stands of Spartina capensis in saltmarsh habitats within Langebaan and knysna lagoon, Cape Province. It was absent from rocky sores and from saltmarshes east of Knysna. The shell, radular and penial morphology are described. L. rudis from both localities bore tessellated colour patterns similar to those of British saltmarsh ecotypes. The Knysna population contained individuals with a unique amber background colour. The shells from Knysna and Langebaan were very thin in accordance with the sheltered habitats. The number of embryos carried in the brood puch was similar in both countries. Sexual maturity was attained at about 4 mm shell length; the male and female modal sizes were 4.9 mm and 5.1 mm respectively at Langebaan. No. published records were found for L. rudis in South West Africa. Some possible origins of the South African L. rudis populations are discussed.