Gephyrocapsa kennettii sp. nov., a new calcareous nannofossil species from the Middle Pleistocene, Solomon Sea, western equatorial Pacific
Gephyrocapsa kennettii sp. nov., a new calcareous nannofossil species from the Middle Pleistocene, Solomon Sea, western equatorial Pacific
复制标题
Gephyrocapsa kennettii sp.
作者：
C. Chuang;K. Wei;H. Mii;Hui;L. Lo
通过对赤道太平洋西南部所罗门海ODP 1115 B孔和岩芯MD 05 -2925中更新世沉积物的详细研究，发现了一种新的钙质超微化石群--桥壳类（gephyrocapsid）。本文报道了一新种，肯氏桥球藻Gephyrocapsa kennettii sp. nov.提出并描述了在这项研究与扫描电子显微镜（SEM）图像。这个新种的颗石呈椭圆形，在远端盾上有2至19个风筝状的狭缝，以及一个低角度的拱形桥。远端护罩的狭缝比G少。在所有元素之间都有裂缝的原始huxleyi。当从远端观察时，桥顺时针定向，与长轴成约10度角。远端盾的平均长度为3.26 ± 0.22（1 θ）μ m（n = 36），根据定义，这个新种属于小型Gephyrocapsa组。该物种的年代范围很短，仅为0.520 - 0.465 Ma。它的最后出现基准与海洋同位素第12阶底部的拟Emiliania lacunosa的最后出现基准几乎相同。形态学上，G. kennettii sp. nov.是G. ericsonii和G.原huxleyi和被认为是一个过渡物种之间的杂交起源。
Detailed examinations of middle Pleistocene sediments of ODP Hole 1115B and CoreMD05-2925 in the Solomon Sea, southwest equatorial Pacific, reveal a distinctive new form of the calcareous nannofossil group of gephyrocapsid which has peculiar elongate kite-shaped slits on the distal shields of the coccolith. A new species,Gephyrocapsa kennettii sp. nov., is proposed and described in this study with SEM (scanning electron microscope) images. The coccolith of this new species is elliptical in shape, bearing 2 to 19 kite-shaped slits on the distal shield and a low-angle, raised arch-like bridge. The distal shield has fewer slits than G. protohuxleyi which has slits in between all elements. The bridge is orientated clockwise with am approximate 10 degree angle to the long axis when viewed distally. The average length of the distal shield is 3.26 plus or minus 0.22 (1 theta) mu m (n = 36), and, by definition, this new species belongs to the small Gephyrocapsa group. The chronologic range of this species is short, spanning only from 0.520–0.465 Ma. Its last occurrence datum is almost coevalwith that of Pseudoemiliania lacunosa at the bottom of Marine Isotope Stage 12. Morphologically, G. kennettii sp. nov. is intermediate between G. ericsonii and G. protohuxleyi and considered to be a transitional species originated by hybridization between them.