A bizarre Palissya ovulate organ from Upper Triassic strata of the Zixing coal field, Hunan Province, China

Abstract

Palissya, a little-known reproductive organ with a long history, is recorded from China and Asia for the first time. A new species, Palissya hunanensis (sp. nov.), is described from the Upper Triassic Rhaetican strata of the Zixing coal field of Hunan Province. The ovulate cone has a compound shoot system that consists of a main axis and many helically-arranged axillary structures referred to as female dwarf shoots, each of which is subtended by a bract. Despite a superficial similarity, P. hunanensis differs from the typical species P. sphenolepis (Braun) Nathorst in a number of subtle but consistent features: the cone is much smaller and narrower, the bracts are much thinner, there are fewer pairs of cup-like seed scales, and the seed scales are adaxially attached to a thick axis rather than to bracts. These traits are all distinctly different from other species of the genus. Moreover, SEM observation of the new species reveals morphological features of the seed scales and seeds and details of the female dwarf shoot; significantly increases our knowledge of Palissya; and provides new evidence that it is a conifer. Palissya is related to the Lower Permian Lebowskia, a voltzian conifer bearing ovuliferous structures similar to the bract plus dwarf-shoot organization of Palissya. Palissya-type conifers probably grew in specialized marine-continent habitats, unlike most other extant and extinct conifers that grow in drier upland environments. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg.