Inter-and intraspecific variation in littorina obtusa ta and l. Mariae (gastropoda: Prosobranchia)

Abstract

Studies on Littorina obtusata and L. mariae from a wide range of localities have confirmed the criteria used by Sacchi & Rastelli in separating the species. In addition, the females of the species can be identified by the pigmentation of the ovipositor which in L. mariae lacks pigmentation whereas in L. obtusata it is to varying degrees black pigmented. Shell characters useful for identification in the field, such as the relatively flatter shell of L. mariae, are outlined. Mean adult shell size of both species varies with the exposure of’the habitat, in L. obtusata increasing with decreasing exposure, decreasing in L. mariae. These and other aspects of intra- and interspecific shell variation are discussed. Intra- and interspecific differences have been recorded in the nature of the radular teeth and differences useful in the separation of the species are described. There are few interspecific differences with respect to the reproductive biology of the snails. © 1977 The Malacological Society of London.