Schizolepis mashchukae sp. nov. - new species from Middle Jurassic sediments of Irkutsk coal basin (Eastern Siberia)

The problem of the systematicposition of Schizolepis genus remained to be unsolved for a long time. Earlier it was treated as close to Voltziaceae family. According toanother point of view Schizolepis genus belongs to Pinaceae family. Representatives of Schizolepis genus have actually a series ofsimilar features with recent Pinaceae. Female cones are of cylindrical or conic forms. Seed scales are placed in spiral order on the coneaxis. Scales are compound and are composed of seed and protective scales. Two ovules are located in the base of the seed scale.Representatives of Pityocladus and Pityophyllum genera, which are frequently found in the same burial places as Schizolepis, arepossible vegetative organs. A number of authors considered these features sufficient for direct comparison of Schizolepis genus withrecent Pinaceae. Nevertheless, the presence of bilobular scales and the absence of seeds with thistle-down in representatives ofSchizolepis genus do not allow their identification with Pinaceae family. Female cones and separate scales are described as Schizolepisdaohugouensis Zhang, D'Rosario, Yao, Wu&Wang from the Middle Jurassic sediments of China. A pair of winged seeds is preserved inlifetime connection on one of the scales. This finding provides an additional prove for probable assignment of Schizolepis genus toPinaceae family. The paper gives a detailed description of a new species Schizolepis mashchukae sp. nov. from the Jurassic sediments ofIrkutsk coal basin. An imprint of a separate scale ascribed to that species was found on the right bank of the Iya River nearVladimirovka village (Irkutsk coal basin). Characteristic properties of Schizolepis mashchukae sp. nov species are the presence of longpetiole and deep middle incision reaching the petiole. Petiole divides the scale into two symmetric widely scattered lobes. The mostclose to Schizolepis mashchukae sp. nov. is Schizolepis kuzbassiensis Bat. from the Lower Jurassic sediments of the Kuznetsk basin.

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