A new species of Distichophytum Magdefrau, 1938 from the Lower Devonian of Siberia (the Torgashino locality, Krasnojarsk krai, Russia)

The new species Distichophytum mogilatil Naugolnylch, sp. nov. is described from the lower Devonian deposits of the famous Torgashino locality, Krasnojarsk krai, Siberia, Russia. The new plant has fertile organs of long spicate shape, with sporangia biseriately disposed on a thin fertile stem. Sporangia are short-fusiform, with acute apex. Proximally disposed, well-developed sporangia arc stalked; apical sporangia and sporangia disposed in the middle part of the fertile organ arc sessile. One fertile stem bears up to 50-60 sporangia. Basal parts of opposite sporangia are fused, forming sporangial pairs. Any bracts or bract-like structures arc absent. Fertile and sterile stems arc curved or almost straight, stem surface is smooth, without any leaves or emergence-like appendages. The salt-extracted ovoid organs (hydathodes) arc present just beneath the points of dichotomy of the stems, i.e. in axillary area. In terms of paleoecology and paleoenvironment, the Torgashino locality was formed in a very shallow, pond-like reservoir, most probably weakly saline, lagoon-like, judging from the presence of eurypterids in the same locality. Despite the pond-like reservoirs, where the plants of the Torgashino locality grew, the climatic conditions of this region in early Devonian can be interpreted as semi-arid to arid, because of the red-coloured clastic/terrigenic deposits enriched by oxidized iron, and because of the presence of salt-extracting axil organs, which are present in many taxa of the Torgashino floristic icsemblage (for example, Distichophytum mogilatii sp. nov. and Psilophyton goldschmidii Halle).