New record of alien species in Albania: Isognomon legumen (Gmelin, 1791) (Mollusca, Bivalvia, Isognomonidae)

In the last five years, there have been reports of the non-endemic Indo-Pacific tree oyster Isognomon legumen (Mollusca, Bivalvia, Isognomonidae) species in various areas of the Mediterranean Sea. Three specimens of the species were sampled in three areas of the Albanian coasts between 0.8 m and 1.5 m depth, among the calcareous algae attached to the rocks. An attempt to determine the age of the species and its expansion in the Albanian coast has been conducted based on the number of filaments of the byssus. The results of this study confirmed the identification of the mentioned species in the Adriatic and Ionian seas. Moreover, it concluded that I. legumen is well established on the south-eastern coasts of Albania and its arrival may be mediated by the naval routes that pass through the Otranto channel.