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In the present account three brachyuran decapods,Macropodia linaresiForest & Zariquiey Álvarez, 1964 (Inachidae),Liocarcinus navigator(Herbst, 1794) (Polybiidae) andThia scutellata(Fabricius, 1793) (Thiidae), are recorded for the first time from the Canary Islands. This is the southernmost record ofM. linaresi. Crabs were caught in the frame of a dredging survey. Characteristics of the dredge stations are given, including the identification of 11 accompanying decapod species and 6 marine algae and plants characterizing their habitats.

The thumbnail crab Thia scutellata occurs in the German Bight in at least two stable populations: at Borkum Riff and Loreley Bank. The western (Borkum Riff) population is larger than the eastern (Loreley Bank) one, probably because of the more frequent ingression of south-western warmer water along the Dutch coast. The sediments of these two localities are well-sorted middle sands with a very low amount of finer fractions.

8 pages, 4 figures, 2 tables, [EN] The sublittoral megabenthic assemblages of a northwestern Mediterranean coarse sandy beach exploited for the bivalve Callista chione were studied. The spatial and bathymetric variability of its distinctive faunal assemblages was characterised by quantitative sampling performed with a clam dredge. The taxa studied were Mollusca Bivalvia and Gastropoda, Crustacea Decapoda, Echinodermata and Pisces, which accounted for over 99% of the total biomass. Three well-differentiated species assemblages were identified: (1) assemblage MSS (Medium Sand Shallow) in medium sand (D50=0.37 mm) and shallow waters (mean depth =6.5 m), (2) assemblage CSS (Coarse Sand Shallow) in coarse sand (D50=0.62 mm) in shallow waters (mean depth =6.7 m), and (3) assemblage CSD (Coarse Sand Deep) in coarse sand (D50=0.64 mm) in deeper waters (mean depth =16.2 m). Assemblage MSS was characterised by the codominance of the bivalves Mactra stultorum and Acanthocardia tuberculata. C. chione was dominant in both density and biomass in assemblages CSS and CSD. The occurrence of the crab Thia scutellata also characterised assemblage CSS, whereas the occurrence of the sea urchin Echinocardium mediterraneum characterised assemblage CSD. A depth breaking point of around 10 m determined the discontinuity between assemblages CSS and CSD, which was related to the closure depth of the beaches in the study area. Species richness was highest in the coarse sand communities; however, Shannon-Wiener diversity and Pielou equitability indexes were higher in the shallow fine sand community, [ES] Se han estudiado las comunidades megabentónicas sublitorales de playas de arena gruesa afectadas por la pesquería del bivalvo Callista chione en el Mediterráneo noroccidental (Maresme). Se ha caracterizado la variabilidad espacial y batimétrica de las comunidades faunísticas presentes mediante un muestreo cuantitativo utilizando un rastrillo de bivalvos. Los taxones estudiados fueron Mollusca Bivalvia y Gastropoda, Crustacea Decapoda, Echinodermata y Pisces, los cuales representaron más del 99% de la biomasa total. Se identificaron tres comunidades bien diferenciadas: (1) comunidad MSS en arenas medias (D50=0.37 mm) y poco profundas (profundidad media =6.5 m), (2) comunidad CSS en arena gruesa (D50=0.62 mm) en aguas someras (6.7 m), y (3) comunidad CSD en arenas gruesas (D50=0.64 mm) en aguas más profundas (16.2 m). La comunidad MSS se caracterizó por la codominancia de los bivalvos Mactra stultorum y Acanthocardia tuberculata. C. chione dominó en densidad y biomasa en las comunidades CSS y CSD. La presencia del braquiuro Thia scutellata también caracterizó la comunidad CSS, mientras que la presencia del erizo Echinocardium mediterraneum caracterizó la comunidad CSD. Se detectó una discontinuidad entre las comunidades CSS y CSD a una profundidad de unos 10 m, la cual está relacionada con la profundidad de cierre de las playas del área de estudio. La riqueza específica fue mayor en las comunidades de arena gruesa, no obstante los índices de diversidad de Shannon-Wiener y de equitabilidad fueron superiores en la comunidad de arenas finas, This paper is a result of the research project "Avaluació de l'estat del banc natural de petxina lluenta del Maresme" funded by the Departament d'Agricultura, Ramaderia i Pesca - Generalitat de Catalunya. PA and MR are part of the research group 2009_SGR_1364 of the Generalitat de Catalunya

There are sporadic records of Thia scutellata from Carmarthen Bay, Cardigan Bay and off the north coast of Wales. Relative scarcity of this small burrowing crab is probably due to habitat specialization. It lives in loose very well sorted medium sand, as typically found in parts of sand waves.

Three specimens of the crab Thia scutellata (Fabricius) have been recorded on the southwest coast of Norway at 3 m depth. This is the first published record of this species from Norway.