Thalassas, 27 (2): 23-35 An International Journal of Marine Sciences PATTERNS OF SPATIAL DISTRIBUTION OF CEPHALASPIDEANS (MOLLUSCA, GASTROPODA) IN SUBTIDAL SOFT BOTTOMS JUAN MOREIRA(1), ANTÍA LOURIDO(2,*), EVA CACABELOS(2,**) & JESÚS S. TRONCOSO(2) Key words: Cephalaspidea; benthos; assemblages; sediment; Iberian Peninsula; Atlantic Ocean. ABSTRACT any given kind of sediment (coarser sandy sediments or fine sand-mud); other species such as Retusa Cephalaspidean gastropods are common truncatula showed, however, eclectic patterns of components of shallow soft-bottom benthic distribution, which might be related to their life cycle assemblages; they are, however, often overlooked in and other factors such as availability or preference numerous studies because of the small size of many of prey. species. The diversity, composition and distribution of cephalaspidean assemblages at three different bays INTRODUCTION located in NW Iberian Peninsula are described from quantitative data. In general, patterns of composition The Cephalaspidea constitutes a widespread and of cephalaspidean faunas varied across locations; diverse group of opisthobranchs (Wägele, 2004), which in two out of three locations there were no patterns are well represented in marine soft bottoms (Franz, of distribution that could be related to sedimentary 1970; Howard et al., 1994). In fact, many species composition. Some species seemed to be present in are provided with a cephalic shield, which helps the animal to burrow in the sediment (Fretter & Graham, 1954). The taxonomic status and family composition (1)Departamento de Biología (Zoología), Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, of the Cephalaspidea has been questioned in the last E-28049 Madrid, Spain. years (see, for example, Haszprunar, 1985; Mikkelsen, e-mail:
[email protected] 1996; Wägele, 2004; Wägele & Klussmann-Kolb, (2)Departamento de Ecoloxía e Bioloxía Animal, Facultade de Ciencias, Campus de Lagoas-Marcosende s/n, Universidade 2005; Malaquias et al., 2009a,b).