中国早二叠世早期一种虫囊蕨(新种)(观音座莲目)的解剖构造

Anatomy of a New Species of Scolecopteris (Marattiales) from Early Stage of Early Permian in China 

报道了山西太原西山煤田早二叠世早期太原组上部７号煤层煤核中一种具解剖构造的观音座莲目生殖器官化石。经对比研究，将其归入辉木科虫囊蕨属（ＳｃｏｌｅｃｏｐｔｅｒｉｓＺｅｎｋｅｒ）。它与虫囊蕨属已有的４个组（共２９个种）都不一样，因此代表了一个新的类型：Ｓｈａｎｘｉｅｎｓｉｓ组，标本被命名为山西虫囊蕨（新种）Ｓｃｏｌｅｃｏｐｔｅｒｉｓｓｈａｎｘｉｅｎｓｉｓｓｐ．ｎｏｖ．。其主要特征是：生殖小羽片可能为栉羊齿型，聚合囊着生于小羽片背面的侧脉上，沿中脉两侧排列，各有一行，每行大约有１０枚，侧脉不分叉；叶片边缘具裂片并背卷，将聚合囊半包围；聚合囊椭球形，高０．７～０．８ｍｍ，直径０．６～０．７ｍｍ，顶端钝圆，基部呈心形，具小的柄，仅在柄的基部见有维管组织；聚合囊由５～７（多为６）个纺锤形孢子囊构成，它们的基部融合在一起，着生于柄的顶端，中央薄壁组织柱不发育；孢子囊面向外的壁在基部由２～３层细胞构成，中部变薄，为１～２层，至顶部又变为２～３层细胞厚；侧壁在成熟时分离，由单层栅栏状细胞构成，厚度均一，开裂沿面向内的壁的中部进行，纵裂；孢子囊顶端直，不弯曲；孢子小，圆三角形或近圆形，直径一般１１～１４μｍ，具三缝，表面光滑或?

Scolecopteris Zenker, a kind of anatomically preserved fertile foliage of Late Paleozoic Marattiales,has been well studied in Euramerican Flora. It is composed of 28 species which can be divided into four forms(groups) mainly based on modified or unmodified pinnules, the variation of the outer facing sporangial walls, and with or without a prominent central parenchyma area. In contrast, Scolecopteris Zenker in Cathaysian Flora has been poorly studied so far, and only one species S. sinensis Zhao, was reported in 1991 which was considered as a member of Minor Group. The paper reports a second species of Scolecopteris, i.e. S. shanxiensis sp. nov., which differs from the above four groups in that its outer facing wall of the sporangia is thick at the base and top (2～3 layers of cells), and a little thinner (1～2 layers of cells) at the midlevel of the synangia. So a new group, Shanxiensis group, is set for the new species. The other characteristics of Shanxiensis group is comparable with Minor group.The new species comes from the coal balls in Coal Seam No.7 in the upper part of Taiyuan Formation (early Early Permian) from Taiyuan, Shanxi, China. The identification of Scolecopteris shanxiensis sp.nov.:The fertile pinnule probably pecopterids, 5.5～6.0 mm in length and 2.0～2.2 mm in width. The lateral extensions of the lamina of the pinnule bend abaxially and above the synangia. The synangia arrange along the sides of the midrib of the pinnule and there are about 10 synangia in each row. The synangium is elliptical in longitudinal section and radial in cross section, 0.7～0.8 mm in height and 0.6～0.7 mm in diameter.Each synangium has 5～7 (mostly 6) fusiform sporangia fused at the base and attached to the top of the synangial pedicel. The outer facing wall of the sporangia consists of 2～3 layers of cells at the base and becomes thinner at the midlevel (1～2 layers of cells), and at the top of the synangia the wall become thicker again. The cells of the outer facing wall of the sporangia are elongate in the longitudinal sections.The lateral and inner facing walls of the sporangia are one cell thick.The synangial pedicel is small. Spores in situ are small, generally 11～14 μm in diameter, spherical or rounded triangular, trilete and smooth walled.