Asthenopodichnium in fossil wood: Different trace makers as indicators of different terrestrial palaeoenvironments

The ichnospecies Asthenopodichnium xylobiontum comprises U-shaped traces in wood, usually attributed to the activity of mayfly nymphs (Insecta, Ephemeroptera), which indicate the presence of freshwater palaeoenvironments. The record of a new ichnospecies in wood, Asthenopodichnium lignorum, in the Miocene of New Caledonia, strongly indicates that it may correspond to other trace makers because the potential producing Ephemeroptera are absent around these Miocene oceanic islands and in a wide area comprising New Zealand and Australia. We present herein the evidence for wood rotting fungi as potential trace maker of the new ichnospecies that has been previously recorded from Argentina, Egypt, Czech Republic, USA, and Lithuania. The new ichnospecies A. lignorum, in contrast with A. xylobiontum, is an indicator of terrestrial, humid to subhumid, palaeonvironments.

► We challenge the attribution of Asthenopodichnium xylobiontum to mayfly activities.
► Asthenopodichnium lignorum isp. n. is described from New Caledonia.
► Burrowing mayflies are absent in this geographic area.
► We attribute A. lignorum to fungus activities.
► Palaeoecological implications of fossils attributed to A. xylobiontum are reconsidered.