A new species Torreya with the seed-bearing structure from the Lower Cretaceous of northwestern China and its evolutionary significance

Taxaceae is a special member of the Mesozoic flora mainly found in the Northern Hemisphere. However, Taxaceae fossils did not show abundance in the Mesozoic, particularly lacking twigs with information on reproductive organs. The new species Torreya jiuquanensis sp. nov. from the Lower Cretaceous of the Jiuquan Basin, Gansu, NW China provides valuable insights in seed-bearing structures of Torreya. Firstly, we present a comprehensive morphological description of Torreya jiuquanensis and it is distinguished from analogous fossils by more slender leaves and the obovate ovule. Secondly, phylogenetic analysis was utilized to determine that the position of Torreya jiuquanensis is located in the same clade as Torreya taxifolia. Meanwhile, the remarkable traits of Torreya jiuquanensis indicated that Torreya had demonstrated morphological stasis at least since the Early Cretaceous. Finally, through the examination of other genera within Taxaceae, it proposed that morphological stasis is not only observed in Torreya but also prevalent across nearly all genera of the Taxaceae, which are characterized by an evolutionary hysteresis. Moreover, a reinvestigation of the global fossil records and paleogeographic distribution of Torreya have revealed that Torreya was primarily restricted to the Northern Hemisphere in the Mesozoic, and multiple climate fluctuations were key drivers behind shifts in Torreya diversity and range migration.