Female reproductive structures of Ginkgo gomolitzkyana N. Nosova, sp. nov. from the Middle Jurassic of Angren (Uzbekistan)

Ovules (seeds) of Ginkgo gomolitzkyana N. Nosova, sp. nov. are described from the Angrenian Formation of the Middle Jurassic in Angren, Uzbekistan. Ovules are attached to pedicels with a collar at bases. Collar diameter of G. gomolitzkyana is similar to that of G. ginkgoidea from the Middle Jurassic of Sweden and G. apodes from the Lower Cretaceous of China. Unfortunately the epidermal structures of the two last species are not described. Epidermal patterns of the outer surface of the collar of G. gomolitzkyana are similar to those of G. yimaensis. Lack of data on the structures of the collar inner surface of G. gomolitzkyana does not allow any detailed comparison. G. yimaensis differs from G. gomolitzkyana by 1.5โ€”2 times larger collar diameter. The ovules (seeds) of G. gomolitzkyana are similar to the ovules (seeds) of G. ginkgoidea, G. yimaensis, G. apodes, G. cranei and Ginkgo sp. (Deng et al., 2004), but they are smaller. The cuticle of the integument and the nucellus cuticle of G. apodes and Ginkgo sp. are not described, what does not allow a comparison with them. G. cranei, unlike G. gomolitzkyana, has thicker outer cuticle of integument and lacking papillae on the subsidiary cells of the stomata. The structures of megaspore membrane are studied only for G. ginkgoidea and G. yimaensis. They are similar to the structures of G. biloba and G. gomolitzkyana. Megaspore membrane of G. ginkgoidea is thicker, than that of G. gomolitzkyana. The dimensions of lacuna and bacula of G. ginkgoidea are not specified. The bacula of the megaspore membrane of G. yimaensis are smaller, than those of G. gomolitzkyana. In addition, G. yimaensis differs from the new species by the curved anticlinal cell walls of the outer integument epidermis. Unlike G. gomolitzkyana anticlinal cell walls of the nucellus of G. ginkgoidea are sometimes sinuous and mostly puncticulate. The seeds of G. biloba are five times larger than seeds of G. gomolitzkyana. The thickness of the outer integument cuticle of the living species is larger and the bacula of the megaspore membrane are thicker. This is the first record of the female reproductive structure of Ginkgo from the Jurassic in the Middle Asia.