Shungo Kawagata

ACAROTROCHUS LOBULATUS , A NEW GENUS AND SPECIES OF SHALLOW-WATER BENTHIC FORAMINIFER FROM MECHERCHAR JELLYFISH LAKE, PALAU, NW EQUATORIAL PACIFIC OCEAN

Acarotrochus lobulatus, a new species of shallow-water calcareous benthic foraminifer, was found in core material from the meromictic Mecherchar Jellyfish Lake of Palau, northwestern equatorial Pacific. The species belongs to a new genus, Acarotrochus, which is assigned to the Family Discorbidae Ehrenberg, 1838. The principal characters of Acarotrochus are a low trochospiral test with a foramenal plate of an extension of septal flap dividing a main chamber lumen and foliar chamberlet, a deeply incised umbilical intraseptal interlocular space which is half-covered by the backward extension of the folium, and the foliar aperture opening at the peripheral end of the foliar chamber. This new species has been found only in the calcareous layer in the core investigated, where the age is estimated to be ~100 years B.P. (end of the Little Ice Age). It may have since been extirpated from the lake.

Middle Pleistocene to Holocene Upper Bathyal Benthic Foraminifera from IODP Hole U1352B in Canterbury Basin, New Zealand

Abstract. IODP Expedition 317 recovered a 550 m-thick sedimentary sequence spanning MIS 63–MIS 1 (last 1.76 Ma), except for early MIS 5–MIS 3, from the upper bathyal zone (344 m water depth) of Canterbury Basin, east of New Zealand (Hole U1352B). Thus, this hole was chosen as the sole, well dated core to investigate timeseries changes in the benthic foraminiferal fauna and paleoceanography on the upper slope off Canterbury during the Pleistocene. This paper describes and illustrates the taxonomic character of the benthic foraminifera for the upper 252 m of the hole, spanning the last ca. 880 ka. A total of 179 species, including unidentified species, were found and comprise 4 agglutinated species (all in Suborder Textulariina), 11 porcelaneous species (all in Suborder Miliolina), and 164 hyaline species (3 Spirillinina, 76 Lagenina, 3 Robertinina and 82 Rotaliina). Many of these species are Recent shallow- and deep-water benthic foraminifera that have been recognised previously around New Zealand or species found in the Cenozoic onland strata in the Canterbury region. However, many species with a lower frequency of occurrence have not hitherto been found in New Zealand waters, but had been reported in the Pacific or the South Atlantic oceans. Three new species (Palliolatella grenfelli sp. nov., Palliolatella haywardi sp. nov. and Rotaliella sabaae sp. nov.) are described here.