本文报道发现于内蒙古乌达煤田早二叠世太原组顶部火山凝灰岩层中的莲座蕨类植物一新种Eoangiopteris con-gestus sp. nov., 标本包含有机连生的辉木型茎干, 栉羊齿型营养羽片和始莲座蕨型繁殖羽片。其中营养羽片为三次羽状复叶, 末二次和末次羽片均为线形, 小羽片栉羊齿型, 卵圆形, 中脉下延, 侧脉分叉一次, 属于东方栉羊齿Pecopteris orientalis (Schenk) Potonié类型。繁殖小羽片与营养小羽片同形; 两侧对称的聚合囊成单列分布在中脉两侧, 排列拥挤, 由6–8个孢子囊组成, 通过一个薄壁组织构成的聚合囊托与叶片相连; 孢子囊呈纺锤形, 无环带; 孢子囊面向外的壁2–3层细胞厚, 面向内的壁厚度仅1层细胞。原位孢子为三缝孢, 椭圆形至圆形, 表面具小刺状纹饰, 可与分散孢子属Apiculatisporites对比。当前始莲座蕨属植物的发现代表其在华夏植物群目前最早的化石记录。此外, 这些两侧对称的聚合囊明显区别于以往报道中与东方栉羊齿叶型化石连生的辐射对称聚合囊类型(星囊蕨Asterotheca), 表明在古植物学研究中一种化石羽片类型可能对应多种繁殖器官类型。

A new marattialean fern Eoangiopteris congestus sp. nov. is described from the volcanic tuff bed in the uppermost part of the Taiyuan Formation, within Wuda Coalfield, Inner Mongolia. It consists of organically connected Psaronius –type stem, Pecopteris –type vegetative fronds and Eoangiopteris –type fertile fronds. Vegetative fronds are tripinnate. Penultimate and ultimate pinnae are both linear. Pinnules are typically pecopterid, oblong in outline, with decurrent midvein and once–bifurcated lateral veins. Vegetative pinnules are attributable to Pecopteris orientalis (Schenk) Potonié type. Fertile pinnules are identical to these vegetative pinnules. Bilaterally symmetrical synangia are borne in a single row on each side of the midvein, closely arranged along the lateral veins, and composed of 6–8 sporangia that are attached to a parenchymatous receptacle. Sporangia are elongate and exannulate, fusiform in shape. The outer facing walls of the sporangia are two to three cells thick, while the inner facing walls are reduced to one cell thick. In situspores are trilete, oval to circular in shape with prominently microspinate sculpture. They are comparable to the dispersed miospore genus Apiculatisporites. The new discovery represents the stratigraphically earliest occurrence of Eoangiopteris in Cathaysia. In addition, these bilaterally symmetrical synangia are distinctly different from those radially symmetrical synangia (Asterotheca) which previously were considered to be the fertile organs of Pecopteris orientalis–type pinnules, suggesting one morphotype of fossil pinnule may correspondence to several types of fructifications in palaeobotanical researches.