TAXONOMY OF THE AZPEITIA NODULIFERA GROUP IN LATE NEOGENE SEDIMENTS FROM THE NORTHWEST PACIFIC OCEAN

Abstract

Upper Miocene, Pliocene, and Pleistocene samples from DSDP Holes 579A, 580, and 581 in the northwest Pacific Ocean were examined in order to identify Azpeitia species in LM and SEM. Azpeitia species which do not possess a marginal hyaline region are here defined as the Azpeitia nodulifera group. The following taxa which belong to this group are discussed and illustrated here: A. barronii, A. nodulifera f. nodulifera, A. nodulifera f. cyclopus, A. nodulifera type 1, Azpeitia sp. A, and one new form, A. nodulifera f. variantia Shiono f. nov. The first report of a pseudonodulus in Azpeitia confirms the earlier familial placement of this genus by Fryxell et al. (1986). A pseudonodulus was regularly found in A. nodulifera f. nodulifera and Azpeitia sp. A, but only rarely found in A. nodulifera f. variantia.