Umaltolepis and associated Pseudotorellia leaves from the Middle Jurassic of Yima in Henan Province, Central China

The seed-bearing structure Umaltolepis is considered to be produced by the same plants of Pseudotorellia leaves based on their close association in the same fossil bearing horizon and similarities in their cuticles, especially in stomatal structures. In this paper we describe new material of Umaltolepis and Pseudotorellia from the Middle Jurassic Yima Formation in Yima, Henan Province, Central China. Umaltolepis yimaensis sp. nov. is an umbrella-like, ovate to elliptical, four-lobed cupule. The cupule lobes are resinous with thick outer cuticle, and scattered, more or less longitudinally oriented stomata. Leaves of Pseudotorellia yimaensis sp. nov. are narrowly oblanceolate, with two veins entering leaf base and dichotomizing once or twice to produce 4–6 parallel veins that converge and join together near leaf apex. The leaves have fusiform resin bodies between neighboring veins, and thick cuticles with scattered, longitudinally oriented stomata on the abaxial side. The stomata of U. yimaensis and P. yimaensis are very similar, both consisting of sunken guard cells surrounding by specialized lateral subsidiary cells and unspecialized polar cells, and both have two bow-shaped cuticular ridges flanking the stomatal pit and a butter-fly like flange between guard and subsidiary cells. The co-occurrence of U. yimaensis and P. yimaensis in the Yima Formation and their similarities in cuticular structures and in the presence of resin bodies further confirm that Umaltolepis and Pseudotorellia are produced by the same group of plants. These fossils also provide new evidence for a high diversity of ginkgophyte reproductive organs in the Middle Jurassic of Central China.