Two new species of Mesozoic tree ferns (Osmundaceae: Osmundacaulis) in Eurasia as evidence of long-term geographic isolation
Two new species of Mesozoic tree ferns (Osmundaceae: Osmundacaulis) in Eurasia as evidence of long-term geographic isolation
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DOI：
10.1016/j.gsf.2020.01.019
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发表时间：
2020-09
影响因子：
8.9
通讯作者：
Ye‐Ming Cheng;Fengxiang Liu;Xiaonan Yang;Tong‐Xing Sun
中科院分区：
文献类型：
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作者：
Ye‐Ming Cheng;Fengxiang Liu;Xiaonan Yang;Tong‐Xing Sun
紫薇科植物的树干和根茎化石为了解其进化史提供了重要信息。由于北半球欧亚大陆中生代树干和根茎的记录有限，阻碍了我们对紫薇科化石多样性的了解。报道了紫薇科植物的两新种--紫薇属。11月和紫草。11月中国记述了产于黑龙江省五大连池和齐齐哈尔的欧亚大陆中生代树蕨属--紫薇属的首次发现，丰富了欧亚大陆紫薇科植物的多样性，为研究该属在白垩纪的分布、辐射和演化提供了重要证据。化石记录表明，紫草物种可能是从一个共同的祖先进化而来的，这个共同的祖先最早出现在盘古大陆的澳大利亚部分，然后传播到古代北美北部和古代东亚。从那时起，它们通过自己的进化路线进化成不同的物种。中国种具有外皮层厚于内皮层的特殊地方性特征，而报道的紫草属植物外皮层较薄，内皮层较厚。长期的地理隔离可能导致了不同的紫草物种的辐射，并出现了地区特有的特征，如中国物种的厚的外层皮质和薄的内皮层。在所有已报道的Omundacaulis种中，发现于中国的两个新种是：澳大利亚侏罗纪的Oderneri和美国侏罗纪的Theo.lemonii，它们在叶柄基部的厚壁组织环内具有特殊的粘液囊群。粘液囊可能在分类群中独立起源，代表对相似生境的趋同适应，而不是共同祖先的遗传遗传。
The fossil trunks and rhizomes of Osmundaceae provide important information about its evolutionary history. Due to limited records of the Mesozoic trunks and rhizomes in the Eurasia of the Northern Hemisphere, our understanding on the fossil diversity of the Osmundaceae is hindered. Two new species of the Osmundaceae trunks,Osmundacaulis asiaticasp. nov. andOsmundacaulis sinicasp. nov. representing the first discovery of the Mesozoic tree fern genusOsmundacaulisin Eurasia, are described from Wudalianchi and Qiqihar, Heilongjiang Province, Northeast China, which enriches the plant diversity of the Osmundaceae in the Eurasia, and provides vital evidence for studying the distribution, radiation and evolution of the genus during the Cretaceous. The fossil records suggest thatOsmundacaulisspecies may have evolved from a common ancestor, which first appeared in the Australian portion of Pangaea, and then spread to ancient northern North America and ancient East Asia. Since then, they developed into different species through their own evolutionary lines. The Chinese species have a special local feature that the outer cortex is thicker than the inner cortex, in contrast with reportedOsmundacaulisspecies having thinner outer cortex and thicker inner cortex. Long-term geographic isolation may have led to the radiation of diverseOsmundacaulisspecies and the appearance of region-specific features, such as the thick outer cortex and the thin inner cortex of the Chinese species. Among all reportedOsmundacaulisspecies, the two new species found in China,O. neriifrom the Jurassic of Australia and theO. lemoniifrom the Jurassic of the USA, have special groups of mucilage-sacs inside sclerenchyma ring of petiole base. Mucilage sacs probably originated independently among taxonomic groups, representing convergent adaptations to similar habitats, rather than indicating genetic inheritance from a common ancestor.