Diatoms in upper Pliocene–lower Pleistocene sediments, subpolar North Atlantic: 4. <i>Thalassiosira hexagona</i> sp. nov.
Diatoms in upper Pliocene–lower Pleistocene sediments, subpolar North Atlantic: 4. <i>Thalassiosira hexagona</i> sp. nov.
复制标题
上新世-下更新世沉积物中的硅藻，北大西洋亚极地：4。<i>Thalassiosira hexagona</i> sp。
DOI：
10.11464/diatom.38.1
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Tatsuya Hayashi & Masao Ohno
中科院分区：
文献类型：
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作者：
Zhong;Q.;Schutgens;N.;van der Werf;G.;van Noije;T.;Bauer;S. E.;Tsigaridis;K.;Mielonen;T.;Checa-Garcia;R.;Neubauer;D.;Kipling;Z.;Kirkevag;A.;Olivie;;D. J. L.;Kokkola;H.;Matsui;H.;Ginoux;P.;Takemura;T.;Le Sager;P.;Remy;S.,;Tatsuya Hayashi & Masao Ohno
在北大西洋次极地的更新世沉积物中发现了一种新的硅藻——Thalassiosira hexona sp. nov.。新种的形态特征是线状条纹，由六个均匀间隔的次中心的花苞组成的环，边缘花苞的单环，与边缘花苞的外部管融合的刺，以及具有肋骨的浅地幔区。这一新种在扫描电镜下很容易被识别出来，因为这两个物种的特征都是亚中心的六角形环和边缘的刺与外管融合。然而，由于在光学显微镜下难以识别物种特异性特征，该新种可能在以往的研究中被误认为是其他具有线状条纹的中心硅藻种。在已知的物种中，T. angute -lineata是形态上与T. hexona最相似的物种，因为两种物种都表现出线状条纹和环状的次中心fultoporturae。然而，除六角形花苞外，所有具有亚中心花苞环的种内花苞面条纹模式和亚中心花苞的数量都发生了变化。亚中心裂口环形的变化与阀面条纹的变化可能存在相互关系。在有两个齿孔和地幔肋的情况下，六角形海硅藻也类似于浮游生物属中的物种。最近的一项分子系统发育研究表明，与T.六边形最相似的物种T. anguste-lineata属于浮游生物的姐妹分支。因此，将来可能需要将T. hexona和T. anguste-lineata转移到另一个属。
A new diatom species, Thalassiosira hexagona sp. nov., is described from lowermost Pleistocene sediments in the subpolar North Atlantic. The new species is morphologically characterized by linear striae, a ring of six evenly spaced subcentral fultoportulae, a single ring of marginal fultoportulae, spines fused with external tubes of the marginal fultoportulae, and a shallow mantle area with ribs. The new species is readily identified under scanning electron microscope observation because both the hexagonal ring of subcentral fultoportulae and the spines fused with external tubes of marginal fultoportulae are species-specific characteristics. However, the new species may have been misidentified as other centric diatom species with linear striae in previous studies because the species-specific characteristics are difficult to identify under light microscope observation. Among the known species, T. anguste-lineata is the morphologically most similar species to T. hexagona because both species exhibit linear striae and a ring of subcentral fultoportulae. However, all species with a ring of subcentral fultoportulae, except T. hexagona, display intraspecific changes in the valve face striation pattern and the number of subcentral fultoportulae. The changes in the shape of the ring of subcentral fultoportulae and the changes in the valve face striation may be related to each other. Thalassiosira hexagona also resembles species in the genus Planktoniella in the presence of two rimoportulae and mantle ribs. A recent molecular phylogenetic study suggested that T. anguste-lineata, the species most similar to T. hexagona, belongs to a clade that is sister to Planktoniella species. Thus, in future it may be necessary to transfer T. hexagona and T. anguste-lineata to another genus.