Data from: Two new species of Nilssoniopteris (Bennettitales) from the Middle Jurassic of Sandaoling, Turpan-Hami Basin, Xinjiang, NW China

Two new species of Nilssoniopteris of the order Bennettitales, Nilssoniopteris hamiensis Zhao and Deng, new species and Nilssoniopteris crassiaxis Zhao and Deng, new species, are established from the Xishanyao Formation (Middle Jurassic) of Sandaoling Coal Mine in Hami, Xinjiang, China, based on leaf macromorphology and cuticular features. N. hamiensis is characterized by its varied leaf shapes and trichome bases of 1–4 cells on the abaxial epidermis, while N. crassiaxis is characterized by its broad midrib (especially near the leaf base) and trichome bases of 1–3 cells on the abaxial epidermis. Both species possess unique venation patterns that are not only simple and free, but also forked and merged to form closed loops. These anastomosing veins are even more complicated in N. crassiaxis in that the veins can fork once, twice, or even three times, the forked veins can later merge with each other or with an adjacent vein to form a closed loop, which may later further disjoin. The generic diagnosis of Nilssoniopteris is thus accordingly emended, particularly in the venation pattern. In addition, the stratigraphic and geographical distributions of all 45 Jurassic Nilssoniopteris species worldwide have been summarized and analyzed to better understand their brief evolutionary history, indicating that Nilssoniopteris might be able to grow not only in subtropical regions as the living cycads are but also in warm climatic regions.基于中国新疆哈密三道岭煤矿西山窑组（Xishanyao Formation，中侏罗世（Middle Jurassic））的叶片宏观形态与角质层特征，本文建立本内苏铁目（Bennettitales）尼尔桑带羽叶属（Nilssoniopteris）的两个新种：哈密尼尔桑带羽叶（Nilssoniopteris hamiensis Zhao et Deng，新种）与粗轴尼尔桑带羽叶（Nilssoniopteris crassiaxis Zhao et Deng，新种）。哈密尼尔桑带羽叶以多变的叶片形态，以及下表皮具1至4个细胞构成的毛基为鉴别特征；粗轴尼尔桑带羽叶则以宽阔的中脉（尤其靠近叶片基部处），以及下表皮具1至3个细胞构成的毛基为典型特征。两个新种均具独特的脉序类型：其脉序既呈简单分离状态，又可发生分叉并相互汇合成闭合环。其中粗轴尼尔桑带羽叶的联结脉更为复杂：叶脉可进行1次、2次乃至3次分叉，分叉后的叶脉可彼此汇合，或与相邻叶脉相连形成闭合环，之后还可再次解离。据此，尼尔桑带羽叶属的属征得到相应修订，尤以脉序特征的修订最为显著。此外，本文汇总并分析了全球范围内全部45种侏罗纪尼尔桑带羽叶属物种的地层与地理分布，以厘清其简要演化历程。分析结果显示，尼尔桑带羽叶属不仅可如现生苏铁类植物般生长于亚热带区域，还可适应温暖气候环境。