早白垩世松柏植物似密叶杉Athrotaxites的三个种

THREE SPECIES OF ATHROTAXITES──EARLY CRETACEOUS CONIFER

本文对产自辽宁铁法盆地早白垩世小明安碑组的Athrotaxites berryi Bell进行了带叶小枝及球果的补充描述,并做了角质层研究。描述了发现于内蒙古霍林河盆地早白垩世霍林河组的一个新种A.orientalis sp.nov.将辽宁阜新盆地早白垩世阜新组原定为Athrotaxopsis? sp的化石改归Athrotaxites属,并定新种为A.magnifolius(Chen et Meng)sp.nov.。后两者也都做了角质层的生物镜下鉴定。全部的三种还都进行了扫描电子显微镜观察。论文对它们的时代,生态及属的含义也做了论述。

<ABSTRACT> Based on the morphological study and that of the cuticles by both microscope and SEM., three species of early Cretaceous conifer are described in this paper. They are Athrotaxies orientalis Deng et Chen (sp. nov.) from the Huolinhe Formation of Huolinhe Basin, A. berryi Bell from the Xiaominganbei Formation of Tiefa Basin and A. magngnifolius(Chen et Meng) Chen et Deng (sp. nov.) from the Fuxin Formation of Fuxin Ba- sin. The paper has also discussed the definition of Athrotaxites and its ecological character- istics and age significances. Description of new species Athrotasites orientalis Deug et Chen (sp. nov.) Ultimate shoots 2 mm thick, irregularly borne on the penultimate shoot at angles of 45 °, curved to the axis. Shoots are helically covered by scale--like leaves. Leaves rhombus, entire, 2.5 mm long and 2 mm wide on the ultimate shoots and 3.5 by 2 mm on the penulti- mate one, crowdedly arranged, appressed, apex acut, abexial surface convex, not keeled. Cuticles are rather thick. The cells in the area near the edges of leaves, oblong, 30x40μm, placed in longitudinal files. At the apex, cells irregular, smaller, about 20μm. In the central area cells square, oblong, placed' in rows. Stomatal areas occuping the two sides of a leaf. Non--stomatal cells in these areas, quadrilateral, polygon and hexagon in shape, a lot of them have a 5 × 20μm crack in ones. The cells of part of edges elongated, hair--like, 50 ～70μm long and l5～20μm in diameter. Almost all radial walls of the epidermal cells are more or less thicken, about 3μm; particularly in stomatal area, more than 5μm thick. Stomata amphistomatic, more on the abaxial surface. Stomata round or elliptic, 50～70μm in diameter, arranged in groups, mainly orientated longitudinal to the axis, some oblique or transverse. Guard cells deeply sunken. Subsidiary actinocytic, 5～7 in number, surrounded by encircling cells. Adjeacent stomata often have common subsidiary. Athrotaxites magnifolius (Chen et Meng) Chen et Deng (sp. nov.) Shoots 3～5 mm in diameter, irregularly branching at 30°～ 45° angles, curved, cord--like. Leaves, occurring hellically, rhombus, entire, 3～4 mm long and 2.5～2.8 mm wide, appressed, each has 1～2 resin canals on its abexial side. Cuticles thick. Epidermal cells near the edges oblong or irregular, typically 30μm long, 20μm wide, placed in longitudinal files. Cells near the apex are smaller. In the central area of the leaf, cells mainly square, partly oblong, 20～35μm, arranged in rows. At the base, cells polygonal with narrow angles, and their radial walls slightly thicken. Non-stomatal cells of the stomatal area, square, hexagon and polygon, 30μm in diameter, irregularly arrangment, radial walls frequently strongly thicken, 3～5μm. Stomata amphistomatic, few- er on the adexial surface. Stomata on the upper epiderm round, about 50μm in diameter, mamly orientated oblique to the axis; on the lower epiderm elliptic, 40～50μm, orientated mainly parallel to the axis. Guard cells sunken. Subsidiary cells monocyclic, 6～7in number, thicken, encircling cells absent. Some of adjacent stomata without subsidiary cells between them.