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

The analysis of the leaf morphology and cuticle microstructure characteristics was carried out on the well-preserved fossil fronds of the fern Cladophlebis from the Lower Cretaceous Bantou Formation in Yongan, Fujian. The fossil is at least bipinnately divided, with a thick penultimate rachis, small pinnules that are entire, closely arranged, with a distinct midrib and dense lateral veins, most of which are once forked. There are no stomata on the upper epidermis, the cell outlines are not clear, and epidermal hairs are occasionally seen. The lower epidermis has stomata, which are arranged in longitudinal bands. The epidermal cells are rectangular or strip-shaped. The anticlinal walls are thickened and relatively straight. The periclinal walls are wavy. The stomata are nearly circular, with a distinct overarching cover, the guard cells are weakly cutinized, and the subsidiary cells are not clearly differentiated. The analysis of the anatomical characteristics of the current fossil pinnules fills the gap in the cuticle microstructure characteristics of the fossils of this genus, and further compares its epidermal characteristics with those of the extant Osmunda japonica and some fern fossils. Combining the analysis of the macroscopic morphology and cuticle characteristics and the comparison with similar species, the specimens from Yongan are named as a new species, Cladophlebis yonganensis Dai et B.N.Sun, sp. nov., and it is inferred that the current fossil represents a certain extinct fern plant.

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.