作 者 ：LIU Zhao-Hua, GENG Bao-Yin, WANG Shi-Jun and LI Cheng-Sen
Keywords:Shanxi Formation, Cuticle, Cordaites,
Abstract:The leaf cuticle of Cordaites neimengensis sp. nov was studied by light and scanning electron microscopy. The specimens were collected from kower Permian of Zhungeerqi, Inner Mongolia (Neimenggu), China. Comparing with other species of Cordaites, it was a new species of the genus, based on the structure of its epidermis. Cordaites neimengensis sp. nov (Pis. Ⅰ to Ⅲ; Text-fig.l,B) The specimen comprises two incomplete leaves over 16 cm in length. One is about 1.4 cm wide at the lower part and 0.3 cm wide at the upper part, with nearly 29 veins per cm and 3 to 5 interstitials. The width of the other leaf is about 7.5 cm at the lower part and 8.2 cm at the upper part with 25 veins per cm and 3 to 5 interstitials. Epidermis amphistomatic. Epidermal cells of upper cuticle aligned in longitudinal rows, nearly rectangular in shape, about 33.6 to 86.4 pm x 10.2 to 28. 8 pm in size. Stomatal apparatus consisting of 2 sunken guard cells surrounded by 2 lateral and 2 polar subsidiary cells. Stomata haplocheillic, about 56.2 pm x 45.5 pm in size, usually arranged in short chains, with one polar subsidiary cell (usually 23.1 to 25.4 pm wide, 34.1 to 39.2 pm long in size) shared with 2 consecutive stomata. The polar subsidiary cells round, oblong or rhomboid in shape. The guard cells reniform or bean-shaped, usually 9.7 to 11.6 pm wide, 23.4 to 29.1 pm long in size. Density and index of stomata about 18/mm2 and 3.2%, respectively. Epidermal cells of lower cuticle also nearly rectangular in shape, about 62.4 to 144 pm × 9.6 to 16.8 pm in size. Stomata on the lower cuticle, haplocheillic, 40.8 pm wide and 48 pm long in size, with a pair of sunken guard cells, which is bean-shaped and surrounded by 2 lateral and polar subsidiary cells. Stomata arranging in parallel bands, typically one, sometimes two. As for the latter, a single row of lateral subsidiary cells (9.2 to 14.4 pm wide, 33.6 to 62.4 pm long in size) is shared with 2 parallel rows of stomata and occasionally also in bands with two rows side by side. In view outside, small papillae on the outer periclinal wall as well as the lateral subsidiary cells. In view inside, some folds along the anticlinal wall but flat about the periclinal wall. Nonstomatic bands usually with 1 to 10 rectangular cell rows. Density and index of the stomata about 209/mm2 and 27.2 %, respectively. 1401%-type: 9342; locality: Heidaigou of Zhungeerqi; Inner Mongolia, North China; Age: Lower Pennian (Shanxi Formation).
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