The first catenicellid (Bryozoa, Ascophora) from Mediterranean shallow waters: a hidden resident or a new immigrant?

Abstract

Catenicella paradoxa sp. nov. is described from Mediterranean shallow bottoms. Colonies are small, rooted, erect and articulated, each segment either sterile unizooidal or bizooidal, or fertile bizooidal. Basal parts consist of an “articulated basal complex”, sometimes related to thick encrusting tubes, invariably followed by morphologically ordinary zooids belonging to each type of segment. The hypotheses of small separate colonies or subcolonies from a network of encrusting tubes are discussed, but relationships with the substratum remain unclear. The species represents the first known Mediterranean catenicellid, a family taxon with a warm, mostly Australasian present-day distribution. Nevertheless, catenicellids and Catenicella species have a long history in the European area from the Middle Eocene to the Early Pleistocene, with at least four different species. In this context, the meaning of C. paradoxa sp. nov. is discussed, bearing in mind problems of species spreading in relation to global warming and human activities.

Keywords:

• new species
• morphology
• attachment structures
• geographic distribution
• Recent

Acknowledgements

Thanks are due to J. Winston (Virginia Museum of Natural History) for information and original photos of “Catenicella contei” from the Florida area, J.-L. d'Hondt (Museum national d'Histoire naturelle, Paris), M. Spencer Jones (Natural History Museum, London), G. Cadée (Netherlands Institution for Sea Research) for bibliographic assistance and to B. Berning (Oberösterreichische Landesmuseum, Linz), D. Gordon (NIWA, Wellington) for useful discussions. I am grateful to R. Di Geronimo for the determination of living algae; V. Di Martino and A. Sinagra for underwater sampling. F. Mondio (Dip. Scienze Biomediche, Sez. Biologia Generale, Cellulare e Molecolare, Univ. Catania) and A. Viola (Dip. Scienze Geologiche, Sez. Oceanologia e Paleoecologia, Univ. Catania) kindly helped with the SEM analyses. P.D. Taylor (Natural History Museum, London) and a second anonymous referee are acknowledged for reading and suggesting improvements to the manuscript. Research was funded by Catania PRA grants to Rosso. Palaeontological paper n. 352.