Smittinidae (Bryozoa, Cheilostomata) from coastal habitats of Lebanon (Mediterranean sea), including new and non-indigenous species

The still poorly-known marine benthos of the Levant (warmest area of the Mediterranean) continuously undergoes changes due to the immigration of exotic species arriving from the Red Sea via the Suez canal, and likely from other tropical and subtropical regions via ship transport. The study of a large collection of bryozoans from the coastal zone (3-35 m) of Lebanon revealed the presence of seven species of Smittinidae belonging to two genera, Parasmittina Osburn, 1952 and Smittina Norman, 1903, whose morphological features and habitat requirements are described here in detail. Only two of these (P. raigii (Audouin, 1826) and P. rouvillei (Calvet, 1902)) were previously known from other Mediterranean areas. Parasmittina serruloides n. sp. and P. spondylicola n. sp., together with P. egyptiaca (Waters, 1909), are presumed to be Red Sea immigrants. The geographic distribution of P. protecta (Thornely, 1905) and S. nitidissima (Hincks, 1880), as well as their habitat in Lebanon and their capacity as fouling species strongly suggest that they are not indigenous to the Levant and that their source populations may be either in the Red Sea or in west Africa. However, alternative hypotheses are also conceivable, such as their persistence in the Levant area as relicts from former warm periods of the Mediterranean, or their existence as groups of sibling species with a more restricted geographical range.