The presence of Phoronis australis (Phoronida) in southern Italian waters

Abstract

Biogeographia vol. XXX - 2011 (Pubblicato il 23 dicembre 2011) La Biogeografia della Sici/ia The presence of Plzoroms auszfralis (Phoronida) in southern Italian waters ANDREA COSENTINO, SALVATORE GIACOBBE, ANDREA POTOSCHI Dzpartimento di Biologia Animale ea’ Ecologia Marina, Universita degli Studi dzq Messina, Salita Sperone 31, 901665. Agata, Messina (Italy) e—maz'l: sgz'ac0bbe@unz'me. it Key words: Phoronida, symbiosis, dispersion, Mediterranean Sea. SUMMARY Since the beginning of the 19905 records of the Phoronida species in the Mediterranean were limited to P/aoro- nis muelleri Selys-Longchamps, 1903, P. /Jippocrepia Wright, 1856 and P. psammop/yila Cori, 1889. Thereafter, P. azutrali: Haswell, 1883, P. oz/ali: Wright, 1856, and three species belonging to the genus Plmronopsis (P. all7omac— ulata Gilchrist, 1907, P. calzfbrnica Hilton, 1930 and P. /aarmeri Pixell, 1912) were recorded. P. azzstralis, distributed in the Indo—Pacif1c and in the south-eastern Atlantic Oceans, was first recorded in the Mediterranean area along the coasts of Spain and Greece. Data reported in this paper have been collected since 2003 and show the current distribution of P. azzstralis in southern Italian waters. Video-photographic records and the examination of the anatomical and ecological features of fifty specimens obtained by means of diving surveys confirmed the presence of the species. Stable populations of P. australir were observed at Milazzo, on the isle of Salina (Sicily) and also on the Cal- abrian side of the Strait of Messina. The species, which prefers to inhabit the mucous tube of Ceriant/Jus spp., was always found in association with C. memlzranacezts (Spallanzani, 1784). As it has happened with other warm-tem- perate species, P. amtralis could have widened its distribution due to the warming of Mediterranean coastal waters, either through the Suez Canal and the Strait of Gibraltar (double-source hypothesis) or only through the latter (sin- gle-source hypothesis). The latter is supported by the earlier occurrence of the population on the Spanish coasts and its relative abundance compared to the Levantine coasts. In both cases, the present record supports the role of the Strait of Messina as a “biogeographic bridgehead” on the scale of the Mediterranean basin. INTRODUCTION The phylum Phoronida comprises only two genera, Plzoronis and Pl70ron0p— sis, with ten Valid species, mostly with Wide geographic distributions. Nine species have been recorded from European waters (Emig et al., 2000), eight of which were also present in the Mediterranean: Pkoronis mulleri Selys—Longchamps, 1903, P. ovalis Wright, 18 56, P. psammopbila Cori, 1889, Plaoronopsis alba- maculata Gilchrist, 1907, P. calzfi2mz'ca Hilton, 1930 and P. /aarmeri Pixell, 1912, which dwell on sandy or muddy bottoms, whereas P. australis Haswell, 1883 and P. bippocrepia Wright, 1856 are hard substrate borers. Up to date the check- list of the Italian marine fauna (http://wwW.sibm.it/CHECKLIST/princi-