College of Palaeontology, Shenyang Normal University, Shenyang, 110034, China.
J Plant Res. 2014 Mar;127(2):209-19. doi: 10.1007/s10265-013-0611-1. Epub 2013 Dec 8.
A new species of structurally preserved fern rhizome, Ashicaulis plumites (Osmundaceae, Filicales), is described from the Middle Jurassic Tiaojishan Formation in western Liaoning Province, NE China. The new species is characterized by a peculiar sclerenchyma mass in the petiolar vascular bundle concavity. This sclerenchyma mass varies from a linear-shape to a mushroom-like shape with a remarkable outward protuberance, which distinguishes the present new species from other Ashicaulis species. Such a protuberance is very rare among osmundaceous ferns, and should represent a unique type for sclerenchymatous tissue in the osmundaceous vascular bundle concavity. Recognition of the peculiar structure of this new fossil species enriches anatomical diversity of permineralized osmundaceous ferns, indicating that the family Osmundaceae might have experienced a remarkable diversification during the Middle Jurassic in NE China. The new species show anatomical similarities to Osmunda pluma Miller from the Palaeocene of North America. The occurrence of A. plumites in the Middle Jurassic of China provides a new clue for understanding the evolution of some members of the living subgenus Osmunda.
一种新的具有结构保存的蕨类植物根茎，名为 Ashicaulis plumites（凤尾蕨科，水龙骨目），来自中国东北地区辽宁省西部的中侏罗世髫髻山组。该新种的特征是在叶柄维管束凹面中存在一个特殊的厚壁组织块。这种厚壁组织块的形状从线性到蘑菇状不等，有一个显著的向外突起，这使它与其他 Ashicaulis 种区分开来。这种突起在凤尾蕨类植物中非常罕见，应该代表凤尾蕨类维管束凹面厚壁组织的独特类型。对这个新化石种特殊结构的认识丰富了矿化凤尾蕨类植物的解剖多样性，表明凤尾蕨科在中侏罗世的中国东北地区可能经历了显著的多样化。该新种与来自北美的古新世 Osmunda pluma Miller 在解剖结构上相似。在中国中侏罗世发现的 A. plumites 为了解一些现存亚属成员的进化提供了新线索。
