Offneria arabica nov. sp. (rudist, Caprinidae) from the Lower Aptian of Jebel Madar (Sultanate of Oman)

Offneria arabica nov. sp. (rudist, Caprinidae) is characterized by the simp licity of the upper valve, well expressed by the subrectangular shape of th e canals where the horizontal partitions are relatively rare, and the weak development of the tabulae. The lower valve is far more complex, which mean s distinctive evolutionary rates for the two valves. The species was found in the Lower Aptian (Shuaiba Formation) of the Jebel Madar, in the foreland of the Oman Mountain nappes. By its overall organisation it belongs to the Arabo-African group of species. Besides its evolutionary characters this f orm is interesting because of its biostratigraphic and palaeobiogeographic potential. (C) 1998 Academic Press Limited.