A fossil vegetative cell of desmidian algae is described as a new species—Closterium mosbruggeri sp. nov. It occurs in middle Miocene (late Serravallian) sediments from Northwest Bulgaria. The present record of Closterium is the first fossil record of this genus in vegetative stage in Europe and the third in the world. The fossil species is characterised by a single, long, straight cell. The cell wall is thin with a smooth surface. The cell is flattened forming a long, frond-like shape tapering at both ends. Closterium is a green alga belonging to the Closteriaceae family, occurring exclusively in freshwater environments.

中文翻译：

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氏梭菌 11月：来自保加利亚西北部中新世的新化石物种

Desmidian藻类的化石营养细胞被描述为一个新物种-梭菌（Closterium mosbruggeri sp。十一月 它发生在保加利亚西北部的中新世（塞拉瓦利晚期）沉积物中。目前的Closterium记录是该属在营养阶段在欧洲的第一个化石记录，在世界上是第三个。化石物种的特征是单个，长而直的细胞。细胞壁薄，表面光滑。电池变平，在两端形成细长的，渐细的叶状形状。梭状芽胞杆菌是绿藻属的一种绿藻，仅在淡水环境中存在。