Abstract: A species of Gilbertella was isolated from dung of swine collected from Hainan, Kwangtung Province, and described as a new species (Gilbertella hainanensis sp. nov.). Morphologically, it differs from G. persicaria, the only other species of Gilbertella, mainly in spore characters. The spores of G. persicaria are oval to nearly spherical, often pointed and bearing 3-6 appendages at each end; while those of the present species are elongate-oval, reniform or oval, with ends obtuse, never pointed and bearing 6-12 appendages. The appearances of the two species in culture are also different. In colour G. persicaria is grayish-brown and G. hainanensis is blackish-gray. When inoculated on peach fruit, G. hainanensis causes no rot, while all strains of G. persicaria isolated from various kinds of substratum readily cause rotting of the entire peach in 5-6 days. The culture of G. hainanensis at hand, being a minus strain, has been found to form mature zygospores when grown together with the plus strain of G. persicaria. The two suspensors of the zygospore thus formed are heterogeneous either in shape or in dimension, one of the suspensors closely resembles those of G. persicaria, while the other is quite different. Type culture of G. hainanensis is deposited in the Institute of Microbiology, AcademiaSinica, Peking, China.