福建永安下白垩统坂头组枝脉蕨属一新种Cladophlebis yonganensis sp.nov.

对福建永安市下白垩统坂头组保存较好的真蕨类营养叶化石枝脉蕨Cladophlebis进行了叶片形态及角质层微细构造特征的分析, 该化石至少二次羽状分裂, 末二次羽轴粗, 小羽片小, 全缘, 排列紧密, 中脉明显, 侧脉密集, 多数一次分叉; 上表皮无气孔器, 细胞轮廓不清晰, 偶见表皮毛; 下表皮具气孔器, 呈纵向带状排列; 表皮细胞长方形或呈条带状; 垂周壁加厚, 较直; 平周壁波状突起; 气孔器近圆形, 具明显拱盖, 保卫细胞弱角质化, 副卫细胞分化不明显.对当前化石小羽片解剖学特征的分析填补了该属植物化石叶片角质层微细构造特征的空白, 进一步将其与现生紫萁Osmunda joponsica以及部分真蕨类化石的表皮特征进行对比, 结合宏观形态和角质层特征的分析及其与相似种类的比较, 将永安的标本命名为一新种, 永安枝脉蕨Cladophlebis yonganensis Dai et B. N. Sun, sp. nov., 并且推断当前化石代表了某一类已经灭绝的真蕨类植物. 

A New Species Cladophlebis yonganensis sp. nov. from the Lower Cretaceous Bantou Formation of Yong'an,Fujian Province

Some fossil remains of morphogenus sterile fern foliage Cladophlebis were collected from the Lower Cretaceous Bantou Formation, Yong'an City, Fujian Province. The gross morphological structure and microstructure of cuticles are studied. These fronds are at least bipinnate, main rachis broad, pinnules small, with entire margin crowdedly attached to the rachis with the whole basis. Their midveins are moderately thick, and the secondary veins at the margin are dense, mostly with a single bifurcation. The upper epidermis is free from stomata, with an indistinct outline of cells, and trichomes can be found sometimes. The stomata on the lower epidermis are longitudinally arranged. The epidermal cells are oblong or elongated, anticlinal cell walls straight or slightly undulant and moderately thick, periclinal walls slightly wrinkled. Stomata are mainly circinal, with well-developed stomata ledges. Guard cells are sunken with weak cutinization, and subsidiary cells are not distinct. The cuticular features described above fill in a gap of the epidermic structure about the genus. Additionally, comparison of epidermic features between present fossils and recent Osmunda joponsica, as well as some filices fossils is carried out. The comparison of gross morphology and cuticular features shows that specimens studied are of a new species and is named as Cladophlebis yonganensis Dai et B. N. Sun, sp. nov., and it is concluded that the fossils studied represent a certain extinct plant of filices.