Fungi–plant–arthropods interactions in a new conifer wood from the uppermost Permian of China reveal complex ecological relationships and trophic networks

An exceptionally well-preserved wood, Ningxiaites shitanjingensis sp. nov., is described from the uppermost Permian Sunjiagou Formation of Northwest China providing new evidence for plant diversity and palaeoecological features of the Cathaysian Flora. The new plant is characterised by a eustelic vascular system with thick pycnoxylic woody cylinder. The cylindrical pith is solid and parenchymatous, surrounded by numerous, discrete endarch primary xylem strands and monarch leaf traces. The wood is especially distinctive by the expanded rays at the pith periphery and the pitted tangential walls of ray cells. The tracheids in the primary xylem have annular, helical and scalariform thickenings from protoxylem to metaxylem. The secondary xylem comprises tracheids, rays and axial parenchyma cells. Tracheids in the secondary xylem possess both alternate and opposite bordered pits on the radial walls. Each cross-field displays 1–2 cupressoid bordered pits. Rays are mostly uniseriate, 1 to 14 cells high. Leaf traces originate individually, bifurcate or not during their horizontal extension through wood, form helical clusters. Two types of arthropod coprolites were recognised in a boring in the pith. The relatively smaller coprolites containing unidentifiable plant tissues are identical with those of oribatid mites, whereas the larger coprolites exhibiting undigested plant cells probably produced by ancient millipedes. In addition to the occurrences of evident fungal hyphae, white-rot pattern and tyloses in the delignificated wood. The current study demonstrates complex ecological relationships and trophic networks occurred during the Lopingian (late Permian).