Psychroptilus burrettae gen. et sp. nov., from the Late Carboniferous of Tasmania, combines characters of the insect orders Palaeodictyoptera and Megasecoptera.Psychroptilusis referred to the Megasecoptera because it lacks paratergal processes on the pronotum, and because its wing venation is simple, with reduced cross veins. However, its wings are not narrowed at their bases, but are as broad as those of the Palaeodictyoptera. It is placed in a new suborder of the Megasecoptera, the Neosecoptera. This suborder differs from the Suborders Eumegasecoptera and Protohymenoptera in having: 1, broad wings that are not narrowed at base; 2, the hind wing slightly broader than the fore wing; and 3, anal veins that all arise from close to the wing base. The insect is possibly the oldest recorded in the southern hemisphere although age determinations of this and the only other known probable Late Carboniferous species,Hadentomoides dwykensisRiek, are not precise. The inclusion of the insect fossil in varve-like sediments and the very few associated fossil species, are indicative of a very cold habitat either at or adjacent to the area producing the sediments. The great majority of insect fossils are associated with abundant plant remains or other fossils indicative of warm conditions in the area of sedimentation. None is recorded from an area apparently as cold as that under whichPsychroptilus burrettaewas preserved.