AXELHEIBERGELLA (OSTRACODA, CRUSTACEA), A NEW GENUS OF MARGINALLY SEPTATE CLADOCOPID OSTRACODS FROM THE CENTRAL ARCTIC-OCEAN

The genus Axelheibergella is established for cladocopid ostracods with well-developed, radially aligned septa between the outer lamella and the relatively wide, free-margin infold parts of the shell. Two deep-w ater species of the genus are described from the Holocene of the Alpha Ridge rise and Axel Heiberg slope, central Arctic Ocean (CAO). Two ot her species are present in the warmer, shallower waters of the Mediter ranean region. Presumably the septa are designed to strengthen the fre e margin of the shell. The relationship of the camerae (interseptal ch ambers) to marginal pore canals in extant ostracods, including the Pun ciacopina, and to the marginal shell glands of cladocopids and halocyp ridid myodocopids is discussed. Cladocopid and podocopid (podocopine) shell ultrastructure is discussed, and new terms are defined. The sept ate frill and its function in the enigmatic Punciacopina are discussed in the light of recent discoveries of the radically different lifesty le of Manawa, and presumably of Puncia and Promanawa, from other non-p unciacean ostracods. It is suggested that the frill of the Punciacopin a is homologous to the ala of some cytheracean (cytherurid) podocopid ostracods. Two unnamed species of Puncia from the New Zealand Pleistoc ene are illustrated, and complement the discussion of septa and camera e in Axelheibergella.