The alcian blue–alizarin red stained specimens of Luciogobius opisthoproctus sp. nov. DOS09993-2, paratype, 24.9 mm SL, Daxi Creek, Yilan County, Taiwan, coll. K.H. Chen, 16 February 2023. Cd indicates caudal vertebrae; Hs indicates haemal spine of caudal vertebrae. Both abbreviations are numbered. The red arrow indicates the first dorsal pterygiophore insertion; the black arrow indicates the first anal-fin pterygiophore insertion.