ABSTRACT
The cementing inarticulate brachiopod Neocrania anomala (Müller, 1776) is commonly found attached to hard substrates mainly in shallow cryptic habitats in the eastern North Atlantic. Its counterpart in the Mediterranean has previously been regarded either as a synonym, variety or subspecies of N. anomala or as a separate species N. turbinata (Poli, 1795), the differences being mainly in the degree of calcification of the valves and the relative development and placement of the dorsal valve muscle scars. Comparison of eastern North Atlantic collections from the Firth of Lorne, Scotland, the Atlantis Seamount, Cape Verde and Algarve, Portugal, with Mediterranean collections from the Straits of Gibraltar to the Aegean-LebanonIsrael area indicates that there are basically two morphotypes, which, where they occur together, are usually separable. One is characterised by a lightly calcified shell, conical dark-brown dorsal valve, subdued anterior adductor scars, prominent brachial protractors divided medially, and distinct brachial retractors, and is the typical N. anomala of the northeastern North Atlantic but also occurs throughout the Mediterranean, other than in its eastern extremity. The other, characterised by a more heavily calcified shell, less conical light-brown dorsal valve, elevated anterior adductor muscle scars, obscure brachial protractor scars on a spike-like ridge, and indistinct brachial retractor scars, occurs throughout the Mediterranean and is regarded here as N. turbinata. This form is also present in the southeastern North Atlantic in Cape Verde and off the west coast of Africa. There is thus no morphological cline between anomala in the west and turbinata in the east in the Mediterranean, as previously suggested. Neither the shell morphology nor geographical distribution of the two forms appears to be the result of ecological factors, such as depth or hydrodynamic action.
