|On the nature of the coastal lagoon winkles attributed to Littorina tenebrosa and Littorina saxatilis|
Barnes, R.S.K. (1993). On the nature of the coastal lagoon winkles attributed to Littorina tenebrosa and Littorina saxatilis. Cah. Biol. Mar. 34(4): 477-495
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723, more
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The name Littorina tenebrosa (Montagu) has been used in the past for (at least) two different winkles: sensu Muus (1967), etc. for the "lagoon winkle", a small, fragile, low-spired form that lives permanently submerged climbing on macrophytes in non-tidal coastal lagoons and lagoon-like pools, and sensu Forbes & Hanley (1853) et al. for a large, intertidal, brackish and sheltered shore form with a high spire that also commonly occurs in lagoons, though usually only on the substratum. The Forbes & Hanley usage appears to be that of the original author and in this usage L. tenebrosa is generally agreed to be synonymous with the sheltered-habitat form of L. saxatilis. Authors using the name sensu Muus et al., however, have argued that their "L. tenebrosa" is not synonymous with L. saxatilis. This conclusion is supported by behavioural, morphological and habitat differences between the lagoon winkle and both lagoonal and marine L. saxatilis, but not by preliminary breeding experiments. In practice, the lagoon winkle is reproductively isolated from even the sheltered-habitat form of L. saxatilis sharing the same lagoonal habitat (L. tenebrosa sensu Forbes & Hanley) and it is here given a new name, L. saxatilis var. lagunae. It is suggested that L. s. lagunae has had a paedomorphic origin. The nomenclature of the exposed- and sheltered-habitat forms of L. saxatilis is also discussed in relation to the nature of the rough winkles in the Venetian Lagoon type locality and in other coastal lagoons; it is concluded that the names L. s. var. saxatilis and L. s. var. rudi both apply to the sheltered habitat form and not, respectively, to the exposed and sheltered forms as used in some recent literature.