First record of the Red Sea immigrant Chrysallida fischeri ( Hornung and Mermod , 1925 ) ( Gastropoda : Pyramidellidae ) from Greek waters

The Red Sea mollusc Chrysallida fischeri (Hornung and Mermod, 1925) was collected in 2005 off Makri, Rhodes, Greece. This is the first record of the species in the Aegean Sea. The presence of both live specimens and shells suggest that C. fischeri is well established in the area.

The first record of C. fischeri in the Mediterranean was from Haifa Bay, Israel (van Aartsen and Carrozza 1979).The species is well established in Israel (Barash and Danin 1986, Bogi and Galil 1999, Mienis and Zaslow 2004).Later, the species was found in south Turkey in the Gulf of Iskenderun (Micali and Palazzi 1992) and in Tasucu (Buzzurro and Greppi 1995).The latest record in the south Adriatic (Mazziotti et al. 2002) reveals that the species has expanded westwards.The present work reports its presence in the SE Aegean Sea.

Methods
Chrysallida fischeri was collected in the framework of a benthic survey in July-August 2005 around the islet Makri (W Rhodes Isl.).Sampling was conducted by scuba diving along nine transects (stations) at 1, 10, 15, and 30 m depth (Figure 1, Annex) using a 15x15 cm quadrat equipped with a net of 0.5 mm opening, on both hard (shallower) and sandy (deeper) bottom.Stations 2 and 3 (at 30 m depth) are located under floating aquaculture fish cages.The material was preserved in 4% formaldehyde with Rose Bengal, and after sorting in 75% alcohol.The specimens are deposited in the University of Athens (collection number ZMUA 4053) and the Hellenic Centre for Marine Research.

Results and Discussion
Among 481 molluscs identified to 38 species, three live specimens of C. fischeri were found in Makri.Following this finding, the shell grit of the samples was sorted, and additional 11 shells were found (see Annex).The species was found only on sandy bottom with or without Posidonia oceanica (Linnaeus) Delile, in July and August 2005, at depths of 10 and 30 m, in four of the nine transects.
Our shells have 6-7 whorls and measure approximately 1.6-2.7 mm in length and 0.76-1.13mm in width.Their color is white or creamy with yellow or brown stripes parallel to the whorls (Figure 2).Biological invasions have been recognized as a serious threat in the Mediterranean (EEA 2006).The main vector of introduction is the progressive penetration via the Suez Canal (Lessepsian migration), and thus the area mostly affected by Lessepsian species is the Levantine Sea (Por 1990, Galil andZenetos 2002).
Pancucci-Papadopoulou et al. ( 2005) have shown an increasing trend in the introduction of alien species in Greece, which is proportionate to the trend of alien species recorded in the Mediterranean (UNEP/MAP 2004) as well as in European Seas (Gollasch 2006).Zoobenthos and particularly Mollusca is a taxonomic group with most representatives among aliens (Streftaris et al. 2005, Zenetos et al. 2005).
Including the present species, the number of alien marine species recorded from Greece (Pancucci-Papadopoulou et al. 2005), rises to 129, 29 of which belong to molluscs.Other findings of alien molluscs (Daskos, unpublished information) support further the statement of molluscan susceptibility to invade and spread in other seas.
The finding of a significant number of C. fischeri specimens, both alive and dead, reveals that the species is well established around Rhodes.This is expected considering a) the geographic position of the area, b) the environmental conditions such as higher temperature and salinity that are more favorable for the alien species arriving via the Suez Canal (Zenetos et al. 2004) and c) the hydrography of the Eastern Mediterranean which is characterized by nearshore sea currents running anticlockwise from the coasts of Egypt south of the Turkey coasts, up to Rhodes island and then to the South Aegean (Poulos et al. 1997).The susceptibility of the wider Rhodes area (Dodecanese) to receive invaders has been demonstrated by Pancucci-Papadopoulou et al. (2005).
The finding of C. fischeri in Rhodes fills the geographical gap between the easternmost parts of the Mediterranean and Pescara region in the Adriatic Sea where it was recently found (Mazziotti at al. 2002), and further documents the species westward expansion following the route of many other Lessepsian immigrants.