Phytophthora pseudocryptogea sp. nov. was discriminated from complex P. cryptogea based on phylogenetic analysis and is a member of Phytophthora Clade 8a and a close relative of P. cryptogea sensu stricto and P. erythroseptica. The discrimination of this species from other P. cryptogea sensu lato lineages raised the question on the host range of P. cryptogea. On the other hand, no studies have been conducted on the host range and pathogenicity of P. pseudocryptogea. In order to determine the potential host range of P. pseudocryptogea and conduct a comparison with other sister taxa, 30 annual as well as 9 perennial plants has been evaluated. Inoculum were prepared using the isolates of P. pseudocryptogea, P. cryptogea and P. erythroseptica. Detached twigs (ca. 20-30 cm) of 21 tree species, and also fruits, tubers and roots of various plant species disinfested and inoculated with the isolates. The results of this study revealed that P. pseudocryptogea was a potential infectious agent of crown and root rot of annual crops including cucumber, melon, watermelon, pepo, pea, chickpea, clover, alfalfa, soybean, tomato, eggplant, potato, green pepper, sunflower, safflower, rapeseed, turnip, cabbage, spinach, sugar beet, beet and rice. Moreover, this species was pathogenic to perennial gerbera, rosemary, apple, sweet cherry, walnut and pistachio. Whiles, P. cryptogea sensu stricto wasn’t pathogenic to green pepper, rice, cucumber, melon, watermelon, alfalfa, soybean, cabbage, apple, sweet cherry and walnut. Moreover, P. erythroseptica was pathogenic to clover, spinach, soybean, tomato, eggplant, potato, cabbage, rice, rosemary and pistachio. All isolates were pathogenic to detached branches of pistachio, Judas tree, big laurel and plane trees during summer and winter. Phytophthora pseudocryptogea isolates, just like their sister taxa caused pink-rot on potato tubers and soft rot on cucumber, apple, tomato, eggplant, kiwi fruit, squash, carrot and beet roots.