The genus Naticarius Duméril, 1806 on Giglio Island Two distinct species encountered in the waters of Giglio Island are usually described to the genus Naticarius: N. hebraeus and N. stercusmuscarum (Figs. 5A,B; 6A). Additionally, one living specimen and three empty shells of an interesting color form of N. stercusmuscarum (Fig. 5 B) were collected at Campese Bay. To our knowledge this color form has not been described in the literature, yet. However, photos of this form have appeared on a website (Gelatolo 2007; www.naturamediterraneo.com). The specimen figured there was also collected on Giglio Island. This color form is so distinct in appearance that the possibility of it being a separate species could not be ruled out entirely. However, initial sequence analysis uncovered no significant differences to typical N. stercusmuscarum. The two species of Naticarius were found living sympatrically on sand bottom in the Bay of Campese and were encountered during day and night dives. Some living N. stercusmuscarum were also collected off the Pt. del Faraglione, and some empty shells were found at Cala dell´Allume. Almost all of the living Naticarius specimens collected were found crawling on the sand surface. The remaining specimens were found burrowed in the sand at depths of 3–5 cm. Both species are very common in the Mediterranean Sea. Unfortunately, the two Naticarius species are often confused with each other, in museum collections as well as in field guides (e.g. Melone & Picchetti 1980). While both species are very similar in shell shape and color pattern, opercular surface and umbilical area (Figs. 5A –B, 6A), living specimens can easily be differentiated by their foot color pattern as well as the coloration of their tentacles (see below). N. stercusmuscarum and N. hebraeus are most frequent on circumlittoral and infralittoral sea beds from 10 to 100 meters in the Mediterranean Sea. Reported occurances in Eastern Atlantic regions (Spain and North Africa: Kobelt 1901, Settepassi 1972, Sabelli 1977, Schiró 1977) remain to be confirmed. Both N. hebraeus and N. stercusmuscarum show many homologies to certain forms of the Eastern Atlantic species Natica multipunctata Blainville, 1825 (syn.: Natica variolaria Recluz, 1844). Thus, published distribution patterns may have included the latter species. On Giglio Island, N. hebraeus and N. stercusmuscarum were found from 2 to 18 meters depths with an average depth of 6 m for N. hebraeus and 8 m of N. stercusmuscarum. One report records N. stercusmuscarum also from the Black Sea (Demir 2002).

Published as part of Huelsken, Thomas, Marek, Carina, Schreiber, Stefan, Schmidt, Iris & Mann, Michael Holl-, 2008, The Naticidae (Mollusca: Gastropoda) of Giglio Island (Tuscany, Italy): Shell characters, live animals, and a molecular analysis of egg masses, pp. 1-40 in Zootaxa 1770 on pages 16-18, DOI: 10.5281/zenodo.182119