Nudasporestrobus ningxicus gen. et sp. nov., a novel sigillarian megasporangiate cone from the Bashkirian (Early Pennsylvanian) of Ningxia, northwestern China

A large monosporangiate fructification Nudasporestrobus ningxicus gen. et sp. nov. and its in situ megaspores are described from the lower Pennsylvanian of Xiaheyan, Ningxia, northwestern China. The cylindrical strobilus is at least 210 mm long, 15–25 mm wide, and possesses a 60–70 mm incomplete peduncle. There are 8–10 imbricate sporophylls arranged in ascending spirals. The sporophylls consist of two parts, a horizontal deltoid pedicel and an upwards-bent, concave lateral lamina; a heel is formed at the corner of sporophyll. Each sporophyll adaxially bears a single elliptical sporangium. The laevigate in situ megaspores in each sporangium with developed subgula formed on the proximal pole. The megaspores are of the Sublagenicula nuda-type and are here described for the first time in situ. The hypothetical parent plant is interpreted as Sigillaria sp., the only vegetative lycopsid remains in the taphonomic association.