A new oospecies of Faveoloolithidae from the Xixia Basin, Henan Province, China and the revision of Parafaveoloolithus

Parafaveoloolithus is an oogenus within Faveoloolithidae, comprising oospecies with uncertain parataxonomic status due to ambiguous microstructures. The revision of problematic taxonomy and the identification of new materials in Parafaveoloolithus can make the classification of Parafaveoloolithus more accurate. Here, we described a new clutch containing 13 dinosaur eggs from the Upper Cretaceous Zhaoying Formation in the Xixia Basin, Henan Province, China by macroscopic measurement and microscopic observation (PLM, CL and SEM). Compared with other oogenera of Faveoloolithidae, these specimens could be assigned to Parafaveoloolithus based on the subspherical shape, columnar eggshell units and partially developed secondary eggshell units. A new oospecies of Parafaveoloolithus, Parafaveoloolithus xixiaensis, was further erected on the basis of the subspherical shape (average 84 in shape index), small size (average 132.4 mm in length and 111.3 mm in width), the parallelly arranged slender eggshell units with a width of 0.05–0.11 mm and wide pore canals with a width of 0.10–0.23 mm in the radial sections, as well as the honeycomb- like structure in the tangential sections. Radial sections of P. xixiaensis oosp. nov. show a single structural layer composed of columnar eggshell units and straight pore canals; some secondary eggshell units are present in the radial sections. The parataxonomy of Parafaveoloolithus guoqingsiensis is revised to Propagoolithus guoqingsiensis based on the branched eggshell unit and smaller pores near the outer surface of the radial section, and the smaller eggshell thickness. Duovallumoolithus is considered an invalid oogenus in Faveoloolithidae, and Duovallumoolithus shangdanensis is assigned to the new combination Parafaveoloolithus shangdanensis. The geographic distribution of Faveoloolithidae is mainly restricted to China, Mongolia and South Korea of East Asia, and P. xixiaensis oosp. nov. provides new material and a complete clutch of Parafaveoloolithus. The assignment of Parafaveoloolithus provides important references for the study of parataxonomy, geographical distribution and clutch structure in Faveoloolithidae.