Abstract

This paper deals with Paracalamitina striata (Schmalhausen) Zalessky, 1934, an equisetophyte of the family Tschernoviaceae from the Permian of Angaraland. New material contributes to a better understanding of this plant, which now can be reconstructed. Paracalamitina striata is an equisetopsid with opposite ribs on the stem. Its main stem bears lateral shoots or shoot and leaf scars, that are located at nodes. Shoot nodes have subcylindrical leaf sheaths. The distal parts of leaves are free and acute. Generative organs are fertile zones, which are formed by numerous sporangiophores with peltate sporophylls. A terminal sterile whorl is presented above each fertile zone. An emended diagnosis of Paracalamitina Zalessky is provided on the basis of new material and re-examination of previously collected specimens as well. The nomenclature and taxonomic status of P. striata also are discussed.

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