Recent Elphidiidae (Foraminiferida) of the south-west Pacific and fossil Elphidiidae of New Zealand

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Hayward, B.W.; Hollis, C.J.; Grenfell, H.R. 1997 Recent Elphidiidae (Foraminiferida) of the south-west Pacific and fossil Elphidiidae of New Zealand. Lower Hutt: Institute of Geological & Nuclear Sciences. Institute of Geological & Nuclear Sciences monograph 16; New Zealand Geological Survey paleontological bulletin 72 166 p.

Abstract: Elphidiidae is a family of mostly shallow-water benthic foraminifera that occur throughout the world at present and in sedimentary rocks of Cenozoic age. Two subfamilies (Elphidiinae and Notorotaliinae) and four genera (Elphidium, Cristatavultatus, Parrellina, Notorotalia) occur in the South-west Pacific region today and two further genera (Cribrorotalia, Discorotalia) are present in the New Zealand fossil record. All 39 species and subspecies of Elphidium, Cristatavultatus and Parrellina in the South-west Pacific today and all 26 fossil species and subspecies of Elphidium and Discorotalia in the New Zealand Cenozoic are described and illustrated, including 12 new taxa: E. aculeatum norcotti (Miocene, New Zealand), E. advenum maorium (Recent, east Australia, New Zealand, South-west Pacific islands), E. albanii (Recent, east Australia, Lord Howe Island), E. carteri (Recent, east Australia; Miocene, New Zealand), E. collinsi (Recent, east Australia), E. crispum waiwiriense (Miocene, New Zealand, E. excavatum oirgi (Recent, New Zealand), E. fijiense (Recent, tropical South-west Pacific islands), E. matanginuiense (Eocene, New Zealand), E. matauraense (Miocence, New Zealand), E.vavauense (Recent, Tonga) and E. vellai (Recent, New Zealand). E. phillipense (Recent southeast Australia) and E. silvestrii (Recent, east Australia) are proposed as replacement names for E. granulosum Collins and E. macellum aculeatum Silvestri. Forty-three percent of these elphidiid taxa in the South-west Pacific today are cosmopolitan, 19 % are endemic to the region as a whole, 27 % endemic just to eastern Australia, 7% to New Zealand and 2% to Tonga. New Zealand has received a sporadic flow of immigrant elphidiids throughout most of the Cenozoic and its fossil record only contains parts of some of the branches of the elphidiid phylogenetic tree. Many of the branches that became established evolved endemic New Zealand taxa, with 48% of New Zealand's fossil and Recent elphidiids endemic. New Zealand time ranges are documented for all species of Elphidium, Discorotalia and Haynesina. Most of the more common species are long-ranging. The biostratigraphically most useful taxa appear to be E. hampdenense (middle Eocene, Heretaungan, Dh), E. saginatum (middle Eocene, Porangan, Dp), E. wadeae (Oligocene-early Miocene, Whaingaroan-Otaian, Lwh-Po), E. kanoum (late Oligocene-middle Miocene, Duntroonian-Waiauan, Ld-Sw), E. aculeatum subrotatum (early-middle Miocene, Altonian-Waiauan, Pl-Sw), E. novozealandicum (late Miocene-Recent, Kapitean-Recent, Tk-Rec) and D. aranea (early-middle Miocene, Otaian-Waiauan, Po-Sw). Elphidium appears in New Zealand in the early Eocene. Diversity and endemism increases to a peak of 18 taxa and 50% endemism in the early Miocene, decl ining through a late Miocene low to the present 13 taxa and 23% endemism. Mean species durations for all Elphidium and Discorotalia in New Zealand is 14.5 m illion years. Endemic taxa are generally shorter-lived (mean 10 m.yr) than cosmopolitan taxa (mean 19 m.yr). Application of modern biogeographic and diversity patterns to the fossil record imply warm subtropical water temperatures around central New Zealand in the early Miocene, some 5-8 degrees C warmer than today. Recent Elphidium and Haynesina live in their greatest abundances (20% or more of total benthic foraminifera) in intertidal and shallow subtidal environments. As herbivores, reliant to some extent on husbanded chloroplasts, they live in the photic zone. They are common members of most benthic foraminiferal faunas in normal marine salinity at inner shelf depths down to about 40 m and in the middle and outer, slightly brackish parts of inlets and estuaries. Taxa living almost exclusively in brackish environments are E. excavatum excavatum, E. excavatum clavatum, E. gunteri and E. phillipense. Those tolerating slightly brackish, as well as normal salinity, conditions include E. advenum botaniense, E. advenum limbatum, E. excavatum sydneyense, E. excavatum williamsoni, E. fijiense, E. lene and H. depressula. All except the early and middle Eocene fossil Elphidium in New Zealand appear to have lived in paralic and shelf environments. Most lived at inner shelf depths, but several species may have lived in lower abundances at middle and outer shelf depths. The early Eocene E. matanginuiense and middle Eocene E. hampdenense and E. saginatum appear to have lived much deeper than subsequent members of the genus, being common in outer shelf and bathyal assemblages. It appears that there was a major ecological shift from deep to shallow water in the middle to late Eocene which possibly accompanied the adoption of a herbivorous feeding strategy and the husbandry of functioning chloroplasts. (auths)

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