The ultrastructure of the chin adhesive apparatus of Pseudogastromyzon was studied with scanning electron microscope. The apparatus are composed of several dermal ridges which consist of unculi arising from single epidermal cells respectively. The unculi possibly serve as adhesive devices to the substrata and as protective organs for the associated taste buds. Two types of adhesive apparatus, termed wave-shaped and club-shaped, can be easily distinguished according to the differences of the ridges. Relative differences between the species of these two types are shown in the distribution of taste buds, maxillary barbels, dorsal rays and ventral rays. These differences indicate that the Pseudogastromyzon can be divided into two monophyletic subgroups. A new subgenus Labigastromyzon, including three species possessing club-shaped apparatus, is proposed. The others possessing wave-shaped apparatus belong to the subgenus Pseudogastromyzon. Labigastromyzon, subgen. nov. Subgen-type: Crossostoma fungi Nichols 1931. Similar to Pseudogastromyzon in general form. But its chin adhesive apparatus club-shaped; two papillae on the base of maxillary barbels; branched dorsal rays 8 apprx 9; branched ventral rays 8. Distribution: China: Hanjiang River, Nongjiang River, Zhujiang River, Xiangjiang River.