|The taxonomy of some British Littorina species with notes on their reproduction (Mollusca: Prosobranchia)|
Heller, J. (1975). The taxonomy of some British Littorina species with notes on their reproduction (Mollusca: Prosobranchia). Zool. J. Linn. Soc. 56(2): 131-151
In: Zoological Journal of the Linnean Society. Academic Press: London. ISSN 0024-4082, more
Organism morphology; Reproduction; Taxonomy; Littorina saxoides Nardo, 1847 [WoRMS]; Littorina nigrolineata Philippi, 1846 [WoRMS]; Littorina patula Gould, 1849 [WoRMS]; Littorina rudis (Maton, 1797) [WoRMS]; Littorina saxatilis (Olivi, 1792) [WoRMS]; ANE, British Isles [Marine Regions]; Marine
The rough periwinkle L. saxatilis is considered, in current literature, to consist of various sympatric 'subspp' and 'varieties'. These, it has been suggested, are incipient spp and are evidence for sympatric speciation. This paper shows that in Wales the 'saxatilis' aggregate consists of 4 separate, fully sympatric spp: L. rudis, patula, nigrolineata and neglecta. Differences between these spp include proportions, sculpture and size of the shell, range of colour patterns, the anatomy of the genitalia, and isozyme patterns. The possible evidence for incipient spp is discussed and rejected. The diversity of penis form amongst the British winkles is remarkable, and it is suggested that in these sympatric spp the structure of the penis could be of importance in spp recognition. The 4 spp occupy different zones on the shore and 3 certainly differ also in their methods of reproduction: L. rudis is ovoiviparous and contains embryos throughout the yr, patula is ovoviviparous but contains embryos only in winter, nigrolineata is oviparous. The reproduction and dispersal methods of all British winkles are reviewed. The evidence available supports the view that non-planktonic dispersal is an adaptation which, in spp whose shell colour varies considerably from one locality to another, enables each population to become adapted to its local environmental conditions. Ovoviviparity occurs in high-shore non-planktonic spp, and may be an adaptation to avoid the dangers of egg desiccation. planktonic dispersal is found in spp whose shell colour does not vary as much as in non-planktonic ones. In these spp, it is argued that a common planktonic pool enables a rapid recolonization in the case of local decrease in population numbers, and also the rapid dispersal of successful mutations.