The occurrence of two morphologically similar Chaetozone (Annelida: Polychaeta: Cirratulidae) species from the Italian seas: Chaetozone corona Berkeley & Berkeley, 1941 and C. carpenteri McIntosh, 1911

The present study reports the spread of the cirratulids Chaetozone corona Berkeley & Berkeley, 1941 and Chaetozone carpenteri McIntosh, 1911 in the Western Central Adriatic Sea, off the coasts of Pescara (Italy). The two species were collected between 2014 and 2016 from soft bottom stations (at depths from 16.5 to 130 m) where the environment was more or less disturbed due to fishing activities. One specimen of C. corona was found also off the coast of Calafuria (Livorno, Italy), representing the first record of this species in the Tyrrhenian Sea. Chaetozone carpenteri could be a native species present in the Mediterranean for a long time but rarely recorded because of taxonomic confusion. Chaetozone corona was already known from the eastern Mediterranean Sea (except from the Adriatic Sea), where it is considered an established alien species. Our results extend the geographic range of these two cirratulid species, providing some information on their ecology and habitat preference. We also suggest a likely vector of spread of C. corona from the easternmost part of the Mediterranean towards the study area. The finding of reproducing specimens of C. corona and C. carpenteri supports the hypothesis that these two species have found a suitable habitat in the Western Central Adriatic Sea, and there will become well established. Although nothing suggests that C. corona would be invasive, it may, however, compete with native species. These findings also seem particularly relevant in order to improve the knowledge of Mediterranean biodiversity