First record of the genusOnchidoris(Gastropoda: Nudibranchia: Onchidorididae) from the South Atlantic Ocean, with the description of a new species from Brazil

Abstract

A new species of the genusOnchidorisis described from the south-western Atlantic, on the coast of Brazil, in the States of Rio de Janeiro and São Paulo. To date, the genusOnchidorisis known almost exclusively from the northern hemisphere, especially the Atlantic coast of Europe and the Mediterranean Sea. The single previous record from the southern hemisphere isOnchidoris maugeansis, described from Australia. This is the first record of the family Onchidorididae from the coast of Brazil.Onchidoris brasiliensissp. nov. is very similar toOnchidoris depressa, from England and the northern coast of Spain, but is distinguished by the presence of a triangular protuberance on the edge of the inner lateral radular tooth and a wide closed branchial circle with tubercles inside. Furthermore, the egg mass of O.brasiliensissp. nov. contains a single row of eggs, whereas that ofO. depressahas multiple rows.Onchidoris brasiliensissp. nov. has lecithotrophic development, the first record of this type of development in the genus. There is a relationship betweenO. brasiliensissp. nov. and the bryozoanParasmittina protecta.