New findings of the female reproductive structures of Umaltolepis Krassilov and associated leaves of Pseudotorellia Florin in the Lower Cretaceous of Mongolia

Abstract

Female reproductive structures of Umaltolepis are recorded in the Huhteeg (=Khukhtyk or Khukhteeg) Formation (Aptian–Albian) of the Baganuur coal mine (Central Mongolia) for the first time. These structures, preserved as dispersed cupules, are very similar to U. mongoliensis from the Tevshiin Govi Formation (Aptian–Albian) of the Tevshiin Govi locality in Central Mongolia. In the Baganuur locality, cupules of Umaltolepis were found in association with Pseudotorellia leaves, described here as a new species Pseudotorellia baganuriana, sp. nov. Leaves of this species are lanceolate, they are distinctive in the elongated epidermal cells of the adaxial leaf side similar across costal and intercostal zones, smooth periclinal walls of the ordinary epidermal cells, stomata arranged in bands on the abaxial leaf side, and the rare presence of small proximal papillae on some subsidiary cells of the stomata. Leaves of the new species differ considerably from the Pseudotorellia leaves associated with U. mongoliensis in the Tevshiin Govi locality. Despite this, we describe the Bagannur cupules as U. mongoliensis since we did not find any significant differences from the Tevshiin Govi material. Based on the updated species composition of Pseudotorellia in the Bureya Basin in Russia Far East (Nosova et al., 2021), we discuss here the type species Umaltolepis vachrameevii and associated leaves.