On the occurrence of the rare deepwater gobiid fish Gobius gasteveni Miller, 1974 in the western Mediterranean (Italy)

Abstract

Marine biodiversity in the Mediterranean Sea is in the process of change. This is often linked to climate change and consequently to the occurrence of exotic species or to their range extension (Bianchi and Morri, 2000; Quignard and Tomasini, 2000). Exotics are also introduced by ships, mostly via ballast water (Galil, 2009). Nevertheless, for small and economically unimportant species like gobies it is often difficult to determine whether a new record indicates range expansion or if it had been overlooked previously. Museum samples collected in past decades or even centuries play an important role in the documentation of biodiversity (Kovacic and Golani, 2007; Liu et al., 2009). Additionally, most data on gobiid fishes are available from species occurring in shallow waters (Miller, 1986; Kovacic, 2001), with virtually nothing known on gobies that settle in deep waters (Ahnelt and Dorda, 2004). Gobius gasteveni Miller, 1974 is representative of such a rare gobiid fish from deeper waters. Originally described from the English Channel, this goby has been subsequently reported from the Atlantic coast of Spain and Portugal, Madeira and the Canaries (summarized in Alberto et al., 1999 and Beldade et al., 2007). In the Mediterranean it is known in only two western locations, near the Alboran and Balearic islands, respectively (Ahnelt and Dorda, 2004). The specimens from the Golfo di Genova (Gulf of Genoa) represent the third and most eastern record in the Mediterranean Sea (Fig. 1). Materials and methods